97 Replies Latest reply on Aug 6, 2014 3:14 PM by kdboyce

    Have a question about multimedia or audio? Ask our Expert, Ken Boyce

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      However, we welcome you to Post Your Question about Communications in the element14 Community Wireless Communications Technology group. You'll find many fellow members and experts who have just the answer you're looking to find! 

       

      Thank You, Your Friends at element14 Community

      KenBoyce

       

      Ken Boyce

      Ken has 40 years of experience and his expertise spans the multimedia, communications and consumer electronics industries.  He has a personal interest in audio and multimedia related subjects.

       

        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
          akhilc
          There are three new TV display invented instead of the CRT display such as LCD,LED and Plasma TVs.But recent advertisement shows LCD and LED TVs are the dominant among the three.Why plasma TVs are neglected ,what is the draw backs of plasma TVs.Which is better, LCD or LED.  Thank You.
          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
            kdboyce

            Hi,

             

            Plasma TV's are essentially charged gas cells (pixels) where the charged gas strikes Blue/Green/Red phosphors, similar to a regular CRT tube where charged electrons strike Blue/Green/Red phosphors on the CRT inner face.  The technology is different, but the principle is the same.  Since the Plasma TV does not involve scanning charged electrons over a relatively long distance to the screen, it can be made very thin relative to a CRT tube.  Plasma TV's have some problems similar to CRT TV's in that you can get phosphor burns and static images on the screen if the phosphors are exposed to one pattern over a long time.  Plasma TV's also consume more power and are hotter to the touch. They are also heavier.  On the positive side, they tend to have better color depth, contrast ratio, blacker blacks, and more rapid response time (less motion smearing).

             

            In general, LCD TV's have almost opposite the characteristics of the Plasma TV.  Cooler, less power consumption, no burnin images, not as heavy, less contrast ratio, less color depth, longer response time, etc.  LCD TV's require a backlight, generally a cold cathode tube or flourescent light.  If it goes out, the entire picture is lost until it is replaced.   But individual pixels can also fail, leaving a very tiny "hole" in the picture which cannot be fixed.

             

            LCD TV's have advanced by offering faster image refresh rates - from 60Hz to 120Hz, and now 240Hz.  The faster refresh rate helps reduce any motion smearing in the image.

             

            Currently Plasma TV's cost less than LCD, and are available in larger screen sizes.

             

            LED TV's currently are not Red/Green/Blue LED based pixels.  Rather, the backlight of the pixel is a white LED.  All the LED's are tightly controlled for the same color temperature and brightness, yielding a very uniform backlight which can also be intensity controlled.  This innovation provides better contrast ratio, color depth, and blacker blacks than non-LED backlit TV's.

             

            In general, advances in LCD TV's have resulted in much smaller pixels (translates into more pixels on the screen and higher resolution of the picture).  Price differences have also been reduced.

             

            So, if you can afford the price,  the choice should be based on how you watch TV...e.g. a lot, or not, High Definition or not, movies vs. regular TV, do you hook a computer to it, etc.

             

            My personal choice is LCD.  Since I have an older one, it is 60Hz refresh and 37".  My next LCD will be minimum 120Hz refresh rate, LED backlit, and probably 55".  I personally do not see enough difference between the 240Hz and 120Hz refresh rate for how I watch TV.  If you watch a lot of high speed action sports, go for the 240Hz refresh rate.

             

            Hope this helps,

            Ken

            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
              mberman

              Hi Ken,

              I liked your comprehensive response to the questions about LCD and Plasma HDTVs.  I have a Lenovo laptop that only has a 9-pin VGA monitor output and my Sharp HDTV does not have this type of input.  Have you used any of the laptop to HDTV "wireless" transmitters available today to view A/V material (e.g., YouTube, online TV shows) from the web on your HDTV?  I have a Wi-Fi set-up at home that works well.  In fact, streaming Netflix video via the Roku receiver I have looks great and has 720p resolution without interruptions. Any suggestions for a good laptop VGA or "USB 2.0" to HDTV wireless transceiver?

              Many Thanks, Mel

                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                  kdboyce

                  Hi Mel,

                   

                  I am sorry, but I have not tried any laptop to HDTV connections.  It should be very similar to connecting a laptop to an outboard projector.  A cable is run from the laptop to the projector, then at the computer you can use ALT-F7 (I forget which exactly) and choose the display mode for 2 monitors.  One will be the laptop screen itself, and the other should then be the HDTV (provided it has an PC input mode).  I am sure you know this already.  However, I would have thought you could get a 9-pin to 15-pin adapter cable somewhere without having to go a "wireless" direction.  I never ran into the problem before.   I have no experience with any product for this purpose other than a cable interconnect.

                   

                  If I get a chance, I may try this over the weekend as I need to take my laptop to a location where there is a small isolated HDTV that does have PC input. But if my memory is correct, everything is 15 pin interconnects.

                   

                  Ken

                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                    kdboyce

                    Mel,

                     

                    I did not find any 9-15 pin cables locally, but check out this link for how to make one.  Good luck.

                     

                    http://www.hardwarebook.info/9_to_15_pin_VGA

                     

                    Ken

                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                        mberman

                        Hi Ken,  Many Thanks for your kind research and the info you provided.

                        Turns out that the VGA output from computers is analog in nature and not directly compatible with the digital HDMI input of HDTVs.

                        And, since I want a "wireless" connection, I found that there are a few VGA to HDMI transceivers available, but I was wondering if you had any experience with them (and you did not not---no problem).  All the Best, Mel

                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                            ksmith

                            Mel,

                             

                            It may be worth checking into different set top boxes that will take streaming video from a computer and display it on your TV. This works great for things like videos and such you have on your computer. Not so sure it would work all that well if you want to display your actual computer screen onto the TV and operate the computer from there.

                             

                            Many of the major game consoles (PS3, XBox, etc) will allow this either natively or with some "tweaking" done. And I know there are a few other types of devices that do it, but I'm not really up on the subject.

                             

                            But I think you're looking for more of a pure adapter cable type of thing and for that I'm not really sure. The issue of the analog vs digital is probably going to be the big issue with finding such a device that would work well.

                             

                            If you do come up with something please post it hear as I wouldn't mind having that as well. Could certainly come up with some nice uses for some older computers if there's an easy (and not expensive) way of doing it.

                             

                            -Kent

                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                        kdboyce

                        Hi Akhil,

                         

                        No problem.  You are welcome.

                         

                        Ken

                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                          tkhwee

                          Hello,

                           

                          Have you come across a camera with timer that capture snapshots of the sky every 5mins? It is used for weather study purpose therefore have to withstand changing tropical climate conditions. One additional feature is to transfer the photo images to a pc for processing either wirelessly or through a cable. Is a microcontroller up to the task of image processing, recognise cloudy, sunny or rainy weather?

                           

                          Best Regards,

                          Mr Tan

                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                              kdboyce
                              Hello Mr. Tan,

                              I have not come across any specific webcam that has onboard timer  capabilities.

                              In general, most all webcams can be connected to a PC,  Some use USB,  and others offer wireless links to the PC.  Depends upon the supplier.  Logitech offers a wide range of webcams, but they are not the only  supplier.  Linksys is also good.

                              The key to using a webcam the way you want will be the software that you  use.  There are many software programs out there for interfacing with  webcams.  Almost all of them allow periodic capturing of images, and  some means of storing them on your PC or uploading them to a image  server on the internet so that you can monitor the camera images from  anywhere.

                              As for "weather recognition", there may be some specialty programs that  do that. I don't know of any, but possibly a specific Google search will  turn up one.  Many of the webcam software packages offer motion  detection as an option to trigger a photograph (think security camera  software).  Clouds moving across the scene could trigger a photograph,  for example, and might indicate some gross change in the weather.  Light  changes may be could be used as well.

                              Since I don't have any experience with the particular type of  application you want to do, I cannot advise any particular solution.

                              But, if you want to experiment with a webcam and software, I would  suggest you buy a wireless Linksys camera  (http://www.linksysbycisco.com/LATAM/en/products/WVC80N ) and use a  software package called "Yawcam"  (http://www.yawcam.com/ ) which is a  freeware package written in Java.   This will quickly allow you to learn  what the capabilities of webcams are.  If you like what you see, you  may also contact the software developer and find out if you can get  access to the Java source code and then modify the software for your  use.  It is worth a try.

                              Kind regards,
                              Ken
                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                              anatomic
                              Hi do you have any information about any product based on BU9458 or BU9457. This is very interesting chips for MP3 decoding controlled by I2C from Romh. I need information if any succesfull product is based on this chip but I need independant opinion (not from Romh) about these chips. Best Regards Alex
                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                  kdboyce

                                  Hello Alex,

                                   

                                  Unfortunately I do not have any product based experience with the BU9458 or BU9457 devices from Rohm.  Nor do I know of a commercial product on the market that uses them.

                                   

                                  Also, it appears that the datasheets for those devices do not offer much info on any application circuit.  So I can't really judge very well a potential product design based on them.

                                   

                                  However, the basic idea of the parts is good in that you have both SD card and USB (flash memory drive) as input sources for the formatted audio material.  Also, a key advantage is that the part can operate self contained as a decoder or can be controlled via an external processor/micro-controller.

                                   

                                  My direct experience with an MP3 player design was one involving a PIC microcontroller + an MP3 decoder which in turn was controlled by a larger CPU running a complex system that happened to need audio at various operations.  That design used a standard SD card with very simple file naming structure which may not meet your needs.  If you want more info on this, let me know.

                                   

                                  Ken

                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                      anatomic

                                      Thank you very much.

                                      I find solution thanks to Element14 PDF files on the server which are not has been available on any other place (even I could find that kind documentation on Rohm site) and later I got help from Anglia by providing to me Demo board and more info, but essentially this is the same information found on Element 14 for BU9458. There has been problem with information about "access code" as that part of information has not being 100% documented ( This is not so obvious until you try to finish product by using available information form PDF). After solving that problems chip is so easy to use and work perfectly. Really nice things are, that firmware inside the chip do all for you and find out about what kind a memory you are using (FAT32, 16, sectors, organizations etc). Even it is possible to read data from USB or SD not necessary MP3. Thanks to BU9458, Microcontroller can use large SD and USB not just to control music. It is possible to Read USB or SD and use this information to flash micro controller or just to use data for some other useful purpose to microcontroller as configurations files for example.

                                      Thank you very much again and best regards

                                      Alex

                                       

                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                          kdboyce

                                          Hi Alex,

                                           

                                          Thank you for updating me on your project.  I am glad it has worked out well for you.  It would be great if Rohm improved their data sheet content.

                                           

                                          Kind regards,

                                          Ken

                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                            davidefa

                                            Hi Aleksandar, I'm trying to understand the "access data" too.

                                            Chould you kindly specify the sequence of commands to extract directory/files names ( in mode3 )?

                                            For example:


                                            - how to read the name of the first folder (It shold be the root folder)?

                                            - how to read the name of the first file in the first folder?

                                            - how to read the name of the second file in the first folder?

                                            ...

                                             

                                            - how to read the name of the second folder ( I mean the first folder in the root folder)?

                                            - how to read the name of the first file in the second folder?

                                            - how to read the name of the second file in the second folder?

                                            ...

                                            - how to read names of subfolders too?

                                             

                                            Regards

                                             

                                            Davide Fabbri

                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                anatomic

                                                Ha-ha... those are exactly questions which I had before I find the solution. And this just proves that definitely there is a need for more information to be added to PDF files about BU9457X.
                                                I will not surprise if you all ready find one for yourself. But if you did not I will provide you more information.

                                                 

                                                I am working on MP3 player with microchip graphic TFT solutions and PIC 32. I also using mod 3 for BU9458 (BU9457 and BU9458 are equally good and no software need to be changed, hardware is the same as well).

                                                What I will explain here I do not claim that this is the very best solution (as there is not documented that this is the right way how need to be done but its work perfectly and I strongly suspect that this is idea of designers of BU9457x how to control BU9457X in order to play right MP3 file.

                                                If you find better solution please let me know although as I say this solution working perfectly well for me.

                                                 

                                                1. Very first you need to use command SET DIRECT and access code, should be 0, 0, 0, 0, 0, 0.
                                                (All binary zeros not ASCII).

                                                2. Then use GET DIRECT

                                                3. Then use READ FILE INFO command

                                                4. Then use READ BUFFER from 20 (think as memory location 20 hex and it is called COMAREA)

                                                Now use access code which you get from process in steps 3. and 4.. You can find access code information from buffer comarea and use this access code to SET DIRECT in next step.

                                                5.SET DIRECT ( StatusOutputOffset[25hex}, ...24,23,22,21…;StatusOutputOffset[20hex])

                                                You are ready for first MP3 to play, by setting command PLAY DIRECT.

                                                6. PLAY DIRECT  this will start the music (if you all ready have your SD or USB files with MP3)

                                                That command will play very first MP3, but what if  you don’t want to play very first song?


                                                Then you need to repeat steps 3. Then 4. N times in case that your song is song number N.

                                                 

                                                But how to be sure that song number N is the right one?

                                                 

                                                Just repeat 3. (Read file info) and after 4. ( Read buffer comarea from 20 hex)


                                                You have information in comarea about name of the song (MP3 file). If this is right one just set command play if not continue to repeat steps 3. and step 4 read until you get right one.

                                                 

                                                 

                                                Now there is more then that. For example you need to wait that BU9458 is available by checking status 1 , 2, 3 etc to confirm that BU945X is analyzed all and is not busy, that BU945X has recognized USB or SD but I recommend at first stage to simplified all by using loops of 10 ms so you can avoid to read STATUS 1,2,3 etc between each steps.  When you have mastered control over BU945X then you can add more improvement (for start use even more then 10 ms, 100 ms will ensure that between each step (commands) are more then enough time and is definitely long enough for all internal processes inside BU9457X so you can use what I explain and without checking STATUS 1,2…


                                                If all of that is not working for you probably you having problems with I2C communication.


                                                Any way I can send you my C code (give me your e mail), if you promise that you will not laugh on my code, but don’t forget…. my code works

                                                 

                                                Best Regards Alex

                                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                  anatomic

                                                  Just to add on my previous e mail as a replay to you.

                                                  Try first to take control over BU9457X as I describe to you, play little bit with chip and then use PDF file to understand how to get names of files and folders (you get names and folders by repeating steps 3 and 4 and reading from COMAREA).

                                                  Although document is not specific for repeating steps 3 and 4 the rest of the document is good.

                                                  So you can use existing Rohm PDF files to get to the bottom of all problems.

                                                  Everything is easy if you manage to do what I explain to you.

                                                  The moment when you do, Rohm document suddenly has a sense… or document is fine but we just can not find sense in the document for that part.

                                                  Whatever is the case I am sure after trying mu suggestion everything will work fine for you…

                                                  Best Regards Alex

                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                      davidefa

                                                      Thank you very much Alex.

                                                      Your description is crystal clear. After the call to SET DIRECT 000000, GET DIRECT, need call READ FILE INFO repeatedly to scroll all files.

                                                      It would be great if you could send me your C code at: element14 at davidefabbri dot net ( No laugh, I swear )

                                                       

                                                      Davide Fabbri

                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                          anatomic

                                                          Yes that is exactly the case and I cannot believe… you explain same thing in just one sentence!

                                                           

                                                          Definitely I should be politicians!

                                                           

                                                          Later one I will send you source code.

                                                           

                                                               Best Regards Alex

                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                              davidefa

                                                              !!!!!!!!!!!!!!!!!!!!!!!!

                                                              !                      !

                                                              Alex for President  !

                                                              !                      !

                                                              !!!!!!!!!!!!!!!!!!!!!!!!

                                                               

                                                              Thank you for sharing your code ( and your schematic ), now I have a good ( and working ) starting point.

                                                              The project is an 'mp3 player for armchairs': a client of us produces relaxing/massaging armchairs, and he want to add this function to his armchairs.

                                                              The player should have an usb input ( so each one with an usb memory could listen to his favorite music ).

                                                              Two versions are planned: a 'dumb version' ( with no display ) and a 'smart version' ( with grafical display ) and bu9457/8 addresses both versions.

                                                               

                                                              P.S. oddly enough rohm applications for bu9457/8 already knows of this strange use ( as an mp3 player for armchairs ), the image is from rohm site

                                                               

                                                              http://www.rohm.com/ad/usb_audio/images/pic_05.jpg

                                                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                  anatomic

                                                                  That’s it! …this is second time that I have been suggested for President and I will go for it!

                                                                  Use of MP3 player in armchair is quite good idea.

                                                                   

                                                                  I like option where you do not need to put headphones on your head and yet music can be loud because speakers proximity to user head at the same time you not distract any body and yet not bother with headphones…just one touch of the button and relax… much more then armchair…not odd at all…

                                                                  Best Regards Alex

                                                                   

                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                          leocranio123

                                                          Hello
                                                          Can you help me I'm not getting the folders view.

                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                            leocranio123

                                                            Can you help me?
                                                            I am not able to read data bu9458
                                                            It has something wrong with i2c but do not know.
                                                            my email leocranio1@hotmai.com
                                                            Thanks ...

                                                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                        Al@Mond
                                                        Ken:  You had previously given me an excellent answer on June 3, 2010 in regard to my efforts to create a better hearing aid device.  Nicolas Gray completelly concurred with your answer. He went so far as to show me the connection of A/D converter to EEPROM. The device would modify the output of the A/D converter using a EPROM to program changed values. Now if you could give me a contact to build a breadboard to demonstrate this improvement I would appreciate that very much.  Al
                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                            kdboyce

                                                            Hi Nathan,

                                                             

                                                            Where are you located?  Maybe there is a prototype house nearby that can be found.

                                                            Also, from your question I am assuming that "hearing aid size" is not the objective yet, but rather proving your alternative data values for correcting or improving hearing is most important right now.

                                                             

                                                            You will need to specify exactly what you want the prototype house to do.  Are you supplying a preferred board layout, or leaving it up to them?  Do you want the builder to source the parts for you?    Questions like these and many more will help you located the right builder.

                                                             

                                                            A company like InDesign  (http://www.indesign-llc.com/electrical_engineering_services.asp?gclid=CKm1woqWs6MCFSH5iAodliq34g) might be the type of company you want if you don't have much direct experience at building electronic projects.   There are many other which can be found via a Google search.

                                                             

                                                            Another one is Gunn Systems at http://www.gunnsys.com/product-dev/

                                                             

                                                            I have no experience with these firms nor do I recommend them (or not) so you need to do your due diligence.  I offer them as examples of the type of firm you may be looking for.  I have no idea of their cost structure either, nor your budget for the project.

                                                             

                                                            I hope this helps you.

                                                            Kind regards,

                                                            Ken

                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                Al@Mond
                                                                Once again your answer to me is right on the button.  Even your guesses as to what I am shooting for gets right to the heart of it. All us millions of hard-of -hearing (HOH) individuals hear sounds with our expensive hearing aids but cannot discern what is being said. Thus the goal of what I want to build is voice clarity and thus understandability.  I am fairly far along in my theorizing and now I want the proof of concept to begin..... I live in the greater Los Angeles area, Torrance California to be specific.   Size shape and all the other  future considerations are secondary at this moment. Constructing a breadboard and programing the EEPROM for a maximum output of understandability is the present goal.    If you can steer me in the direction of a local -that is, a range of 100 miles-  pre-prototype shop that would be greatly appreciated.. I would love to try doing it myself, but there is too much of a learning cure before I could to it effectively.   Again, thanks for your cogent replies.   Nate Almond
                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                    kdboyce

                                                                    Hi Nathan,

                                                                     

                                                                    Happy to help, if I can.


                                                                    I did a quick search in your area, but mostly turn up full fledged electronic manufacturing service houses (EMS).  EMS's are not what you need right now.

                                                                     

                                                                    Other companies I turned up were either IC design houses, or passive component design houses (transformer, etc).

                                                                     

                                                                    The type of company you need may not be in your back yard.  Maybe you could contact the following companies and at least get an idea of what they are willing to do for you at what price.   These smaller companies specialize in design prototypes.  One of them is close to you.

                                                                     

                                                                    GUNN SYSTEMS, INC.

                                                                    E-Mail:gunnsys@att.net
                                                                    Phone:(352) 326-3264 begin_of_the_skype_highlighting              (352) 326-3264     end_of_the_skype_highlighting
                                                                    Fax:(321) 988-0226
                                                                    Address:37703 Ricker Drive
                                                                    Lady Lake, FL 32159

                                                                     

                                                                    Ienso Inc.
                                                                    20 Mural Street
                                                                    ,  Unit 7
                                                                    Richmond Hill, ON   L4B 1K3
                                                                    Canada

                                                                    Phone: 905.763.6938 begin_of_the_skype_highlighting              905.763.6938     end_of_the_skype_highlighting
                                                                    Fax: 905.763.1153

                                                                    Email: mail@ienso.com

                                                                     

                                                                     

                                                                    Mirmar Sensor

                                                                    Mail:
                                                                    P.O. Box            31161
                                                                    Santa Barbara, CA 93105


                                                                    Physical Address:
                                                                    5959 Hollister            Avenue; Suite C
                                                                    Goleta, CA 93117


                                                                    email:
                                                                    info@mirmar.com

                                                                     

                                                                    TEL:                 (805) 895-4608     end_of_the_skype_highlighting


                                                                    Let me know what you find out -  just curious :>)

                                                                     

                                                                    Ken

                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                      michaelkellett

                                                                      Hello Nathan,

                                                                       

                                                                      I don't want to rain on your parade but are you aware of current DSP based hearing aid products. ?

                                                                       

                                                                      If you Google/AltaVista for dsp hearing aid you will get million+ hits - there are even special hearing aid DSPs (eg Ezairo form Onsemi).

                                                                       

                                                                      I feel you might do better to start with a development kit from a DSP supplier rather than paying for a new hardware develoipment.

                                                                       

                                                                      In fact you could probably start with just a PC and a sound card (and some little transducers from www.knowlesacoustics.com ).

                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                          Al@Mond
                                                                          Michael:  Please do rain on my parade.  I live here in sunny southern California and and any rain, parade or no is a gift of the gods. It keeps us from reverting back to the dessert.  So go ahead and downpour if you would-please.   Joking aside, I do appreciate some skepticism for what I am attempting to do.   Now that is what science is all about, isn't it.  I have put my entire working and World War 2 experience in the electronics field and saw the beginnings of radar and TV.  Worked as an electronics maintenance technician at Chicago's Midway and O'Hare airports.  Following which I returned to the University where I received bachelor and master degrees from the University of Southern California.  After graduating, worked in the defense industry building the latest airborne radars for aircraft such as the F14 and F15.   Does all this mean I know anything?  Not really.   As I approached 85 years, as is typical, my hearing got poor, designation is 'hard-of-hearing' (HOH).  After using several brands of hearing aids, I too was complaining "I hear, but I don't understand".  And quickly deduced that I was not hearing consonants, for reasons unknown..   Went shopping on the Internet to find a hearing aid that advertised the two precious words "amplified consonants" because that is where the information is contained.  No such device was to be found.  Thus as I now approach my 90th birthday I set  to work to figure what this confusion (in my mind, at least) was all about.......And now I have some  certainty that I have solved the enigma and believe I am on the proper road to fixing the 'I hear but I don't understand' syndrome.  The very finest of today's hearing aids including those with DSP) do not resolve that problem.    If you feel that the digital signal processor can assist in this matter, I am an anxious listener.  My particular solution does not introduce frequency as a key parameter, but uses a new type of  modulation as it's basis ....If you wish to exchange ideas on the subject that would be very advantageous to me and hopefully also to you. .Best Regards,  Nate Almond
                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                              michaelkellett

                                                                              Hello Nathan,

                                                                               

                                                                              I picked up from your earlier posts that you are planning some signal processing involving ADC and EEPROM and that you don't have any hardware yet. If it were my project I would design and make a custom board but it doesn't look as if you have the resource to do that. So my suggestion was that the cheapest way for you to experiment is to use a ready made DSP development kit - that way you can do almost any imaginable signal processing - frequency domain, time domain, linear, non-linear etc. But the great thing about DSP is its all in software so you can change things cheaply and quickly at the start of the project. In the end you might decide to dump the DSP and use pure analogue for a production design (although if you want a  small hearing aid the investment cost in using your software on an existing DSP willl be much lower than a custom analogue solution).

                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                      Al@Mond
                                                                      Ken:  This is the old engineer  guy who you have helped on several past occasions. Once again asking for some sage  advice from you.   Would you have any clues for me of a  simple circuit design for a digital audio amplifier that I might construct in order to test my unique concept for an improved understandable hearing aid?  It would have to include as a minimum an A to D converter and a EEPROM.  Thank you for any help you can provide.    Nate Almond
                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                          kdboyce

                                                                          Hi Nate,

                                                                           

                                                                          I don't know of a single device of the type you describe.  If one existed, it would have to have separate ability to program the EEPROM.

                                                                           

                                                                          TI has some digital input Class D amps, but high power ~ 20W.  The digital input is in the I2S format, commonly used in consumer electronics audio equipment.  This type of part  does not have any internal EEPROM that could be programmed.

                                                                           

                                                                          Maybe the best bet to prove the concept would be to use a D-A after the external A-D and EEPROM, then feed the new HOH analog input a part like the National LM48310  or other analog input Class D amp at   http://www.national.com/cat/index.cgi?i=i//277  or some similar parts at TI  (TPA2001) at  http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=923&uiTemplateId=NODE_STRY_PGE_T.  You could hear the result on an 8 Ohm speaker,  or thru a headphone if you chose a headphone amplifier from either of these 2 suppliers.

                                                                           

                                                                          Ken

                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                              Natealmond

                                                                              Hello Ken:   From your old friend Nate, the 90+ y/o guy.   When I talk to experts in the hearing aid field I end up proceding down the wrong pathway.  They have the solid belief that improved hearing can be accomplished in the present manner, namely though the control and adjustment of the frequency response characteristics..

                                                                                   Since I come out of the field of radar, my thoughts are  that hearing is in some important details quite analogous. In both there is a detection phase and a lock-on follow-up.  In the hearing process there is similarly a detection phase where sound is first heard, following which as the sound gets nearer it can be judged to be speech and might now be understood.  The entire concept hinges on the fact that there are two components of human speech, two separate languages, interleaved to form into a code of sorts of noise sounds and tones, consonants and vowels.  The big prolem for the deafend is that the noise-like sounds of the consonants are 10,20, 30 dbs lower than vowels.  And that is where the problem lies.  The consonants are the first to be 'lost' as we become deafend.  You have to hear both sides of the speech code in order to understand.  Like in the Morse Code, one must hear both the dits and the dahs in order to understand the message.  Frequency is hardly involved in the process of understanding.   I have spelled it out in the Wikipedia web page under the title  "user:roselamb"  if you have the interest.

                                                                               

                                                                              Finally my question.  Help me to understand how the ADC functions.  Does it take as the input an analog signal, as a voice for example,  and convert it into discreet levels, numbers,  corrensponding to the amplitude of the  input signal?  That would account for the amplitude consideration.  But what happens to the corresponding frequencies of the input signal.  They have to be brought into the equation somehow.  That is where I get lost. Please help me to understand how both amplitude as well as frequency result from the ADC conversion process.    Thanks again.   Nate Almond

                                                                               

                                                                              Message was edited by: nathan alMOND

                                                                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                  michaelkellett

                                                                                  Hello Nat,

                                                                                   

                                                                                  Take a look at en.wikipedia.org/wiki/Digital_audio

                                                                                   

                                                                                  There are loads of references on Wiki to sampling and sampling theory but most are rather confusing.

                                                                                   

                                                                                  If you lookat the diagrams on the page I refer to you can imagine that the signal is represented by numbers like 0,0.5,0.866,1,0.866,0.5,0,-0.5,-0.866,-1,-0.866,-0.5,0 (that's one cycle of a sine wave at 12 samples per cycle).

                                                                                   

                                                                                  You can see that if you plot it out it makes  a sine wave.

                                                                                   

                                                                                  But the bit you are missing is that from just one sample you can tell (almost) NOTHING about the signal. You need to look at several samples to estimate what the signal would look like in the frequency domain.

                                                                                   

                                                                                  This shouldn't be a surprise - if you look at your sine wave plot though a narrow vertical slot you can see only one point, and you can no longer tell what the shape of the rest of the signal is.

                                                                                   

                                                                                  This is why ALL digital filters need more than one sample (usually a lot more) to function and all analogue filters use some kind of energy storage to keep a "memory" of the preceding signal.

                                                                                   

                                                                                  Hope this helps.

                                                                                   

                                                                                  Michael Kellett

                                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                      Natealmond

                                                                                      Thank you very much Michael for the fine understandable explanation.  It seems so logical once you explain it.  In other words, coming out of the ADC are numbers corresponding ( example 0 to 255 for an eight bit ADC) to the input amplitude levels, the twelve levels you used to explain it to me.  Like you said, those levels correspond to just one cyle.   The frequency then is the number of these cycles per second, the hertz, of the input to the ADC.

                                                                                       

                                                                                      Now that I have an understanding, what I wish to accomplish is to reverse this output.  By this I mean, that where the output might be 255, I wish to convert it to a 0.  And do this at each bit level which should end up with the loudest input sounds becoming the quietest and vice versa.  That is what I am trying to accomplish.

                                                                                       

                                                                                      A long time ago Ken Boyce gave me some practical suggestions on how to go about implementing  such a goal.   Don't know it I can still find the email he sent. Can you clue me in again on how to reverse the output numbers of the ADC?  It probably would involve creating a simple arithmetic algorithm which might amount to a software programming exercise.    Give me more of your ideas, if you would please.

                                                                                       

                                                                                      Thanks once again for you highly understandable explanation of the ADC.

                                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                          kdboyce

                                                                                          Hi Nate,

                                                                                           

                                                                                          The suggestion a long time ago was to feed the ADC sample output into a content addressable memory which basically used the ADC output values as the memory address, and for that address, the memory value would be programmed ahead of time to be the opposite of the address.

                                                                                           

                                                                                          So if the sample value was 1111 1111 1111 1111, in the memory at that location would be the number 0000 0000 0000 0000, and so on.

                                                                                           

                                                                                          I believe Nicholas Grey also provided an alternative way.  You should find both by looking at the element14 expert entries under the persons name.

                                                                                           

                                                                                          One thing to keep in mind in that most ADC's have serial data output, not parallel data output.   The problem might be as simple to solve as inverting the bit stream data, then feeding it to a DAC.

                                                                                           

                                                                                          Ken

                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                              Natealmond

                                                                                              Ken and Michael:  Can't thank you two enough for your detailed information with the wonderful tutorial explanations of how the ADC works. It was more understandable than any text might do.   I will follow up on all the web sites you and Michael  provided me in order to help in my greater understanding.

                                                                                               

                                                                                              What is so sad is that all I ever wanted to do was to go out and buy a hearing aid that emphasized the consonants.  The ones I tried don't provide the understandability that is needed. Didn't seem like it was asking too much.  I could not find one word of advertisement  that said the magic words "this hearing aid emphasizes the consonants."   Just that simple.  I had to delve into this further to get the answer.   For persons  with perfect hearing which may describe your own situation, to see this defect in action, try using the system for speaking into a microphone using the Nuance company device called Dragon Speaking (I'm guessing at the exact title).  The written output is typed out on the computer.  The results are pure humor..   Just like the deafened world, it does not detect/hear consonants with the resulting written words and sentences that are hilarious. Yes it is most laughable too when deaf individuals, like the Nuance system,  try to guess at the consonants.

                                                                                               

                                                                                              Since consonant sounds are constructed in a completly different fashion than the vowels, these differences can be used to amplify the consonants. Consonants are always the weaker of the two languages of speech. So what I wish to do in the easiet possible manner (for me at least) is to simply reverse the order of the output of the ADC so now the loudest portion of the speech input, the vowels,  become the quietest. Aah, just what I was looking for.  What is accomplished by this reversal of sound level is to make the consonants loud enough so that the two parts of speech can always be heard and thus understanding by the deafened is accomplished.   Never once was an ear deficiency, such as diminished frequency response addressed. What I have  accomplished by this exercise is to provide an infinitely  better input signal to the ear, or to the hearing aid if one is being used..

                                                                                              This same technique is usable in all speech applications, whether is be in a broadcast studio or elswhere.  No more over-modulation of speech monitoring is required in the broadcast world..

                                                                                               

                                                                                              I offered my ideas to Nuance Communication, to  my University of Southern California,   to Staley Hearing Aid Co., to the State of Israel, got not an ounce of interest.  Now I am looking for Venture Capital to proceed further.

                                                                                               

                                                                                              So I will continue my slow progress in learning how to make this happen, knowing full well that there are millions of technical people like you and Michael infinitely more suited to doing this project.

                                                                                               

                                                                                              Thanks once again for your great patience and wonderful helpfulness.    Nate

                                                                                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                  Natealmond

                                                                                                  Ken and Michael:    Once again this is Nate Almond, the Ancient  One.  By now I have reached the ripe age of 91y/o and have been sidetracked in my efforts at producing an improved hearing aid, what I choose to call an understaning aid.   The reason for the side tracking was the fact that I began studying the structure of human speech and found it had evolutionary impact such that it caused homo sapien to go from just another tribe of something like ape-man to what he now labels himself as "human."  It was the cause of the Cognizant Revolution, call it if you wish, the "missing link,  in the field of paleontology. Ancestors of the hominids used the same language as all other surviving creatures, the common feature being that it was produced sound by means of the vocal chords.  Air from the lungs blowing past the vocal chords, (vibrating membranes)  can produce huge sound levels, right from the instant of birth. It was part of the Darwinian theory of survival of the fittest.  In this case fittist meant developing vocal chords as a protective means.   This continued for more than 2.5 million years of hominid existance in the same manner for all animals excepting homo sapien. About 100 thousand years ago this hominid developed a second  language using  means other than the vocal chords.  The distintively different sounds came from a new source, from the mouth, tongue and lip combination.  And now  the genius idea was born.   The new language was not simply an add-on feature to the old language but was interspersed into the first language to produce the concept of time element into the two languagesystem.  It could now be articulated  such that 'before', 'now' and 'in the future' was part of the new language.  Also, sounding for ideas as greater than, same as, more than, could be articuated.  The new sounds, what is by then  called speech,  became the basis for modern history, science and mathematics of present human existance. Cognizant revolution, indeed! This was a first audible 'publication'. Many thousands of years later, the developemnet of hierographics attempted to put those sounds into a permanent form.

                                                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                      kdboyce

                                                                                                      Nate,

                                                                                                       

                                                                                                      A BIG CONGRATULATION to you on your 91st birthday.  How many don't make it that far?  Furthermore, you still have your brains, and a quest for knowledge and a desire to somehow make the world better for yourself, and in the process, better for others.  Now that is a fullfilled life.  Aside from that I bet you are a real character!

                                                                                                       

                                                                                                      I really am sorry no company has taken up your ideas for possible further development, but overcoming the status quo is always a challenge.  Sometimes you win - other times you don't.

                                                                                                       

                                                                                                      Language is a great thing but the twisting of it we now see in many areas of human endeavor is heart breaking.

                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                              kdboyce

                                                                                              Hello Nate,

                                                                                               

                                                                                              Long time no hear from :>)

                                                                                              I hope all is well with you.

                                                                                               

                                                                                              A very good tutorial on ADC's is at the following URL.

                                                                                              http://www.hardwaresecrets.com/article/How-Analog-to-Digital-Converter-ADC-Works/317/2.

                                                                                               

                                                                                              There are 10 pages, and the link above takes you to page 2 of the tutorial where the meat of the explanation takes place, but you should start on page 1 ( http://www.hardwaresecrets.com/article/How-Analog-to-Digital-Converter-ADC-Works/317/1 ).

                                                                                               

                                                                                              I will answer your question about capturing the frequency information in the following way:

                                                                                               

                                                                                              If you take a look at the article, and at Michael Kellett's reply to you, you already know that the input analog signal gets converted to a digital number by a process known as sampling, which simply means that you take the conversion a some specific time and what ever the signal level is at that time is the level that will be converted to a digital number.

                                                                                               

                                                                                              Intuitively you know that if I only sampled that signal one time, it would not be correct representation of the true input signal. Right?  Kinda like describing an elephant by  looking at a fly on its back.   So, to get a truer representation of the input signal I am going to have to sample it quite often.

                                                                                               

                                                                                              Also intuitively you know that if I sample it more than once, it would be better to sample it at very close intervals rather than at far apart intervals.  Closer interval sampling means that I can capture the smaller variations in the signal better.

                                                                                               

                                                                                              Now imagine sampling a 1KHz sine wave.  Should I sample that once every second? No...since I would only pick up one value on one cycle of the sine wave and miss all the rest.  Ideally, I would want to sample at a rate which is closer to the expected highest frequency of the input signal so I don't miss much during the conversion.

                                                                                               

                                                                                              Fortunately, this problem has been extensively studied, and way back when, a gentlemen by the name of Nyquist developed his famous theorem (paraphrased as follows) which says that if you want fully recover in the analog domain a digitally sampled signal, then you must have orginally sampled it at 2X the highest frequency of interest.

                                                                                               

                                                                                              So for Hi Fi audio which has an upper bandwidth of 22KHz, the ADC samples that signal typically at 44.1 thousand times a second, e.g. a 44.1KHz sample rate.  The beauty of the Nyquist Theorem is that you could feed those 44.1K samples directly to an analog low pass filter that had a upper cutoff of 22KHz and Voila!, out comes your original analog input signal.

                                                                                               

                                                                                              But sample rate is only part of the problem.  You would want to know how closely the sampler actually got the right value, and you would also want to have sufficient resolution in the sampler in order to distinquish correctly one value from another.

                                                                                               

                                                                                              So the ADC has to have a resolution aspect to the number, or what is the precision of the number.  So all ADC's have a resolution specification which says how the digital number (almost always binary) is represented.  For typical audio, the typical resolution per sampled number is 16 bits.  However, professional audio engineers often go to 24, 32, and even higher, bits to get an even closer representation of the input signal.

                                                                                               

                                                                                              And I will add at this point that although I mentioned 44.1KHz sample rate, professional audio is often sampled as high as 384K samples a second which also gives a closer representation of the input signal.

                                                                                               

                                                                                              Modern audio ADC's usually have a selection of bit resolutions and sample rates that enable them to be used with almost any audio input signal.   The higher the bit resolution and sample rate used, the better the input signal in it's entirety is captured.  That means you not only capture the signal amplitudes, you also capture the signal frequency components.....so long as the sample rate is a minimum of 2X the highest audio frequency you want to capture.

                                                                                               

                                                                                              DAC's do the reverse....taking in whatever the digital representation is and converting it back to analog, as well as incorporating digital filters which do the job of the analog filter I was referring to earlier, and Voila! clean analog signal out.

                                                                                               

                                                                                              CODEC's combine both ADC and DAC in one package.

                                                                                               

                                                                                              I hope this helps you.  Enjoy the article.  You will learn perhaps more than you intended.

                                                                                               

                                                                                              Kind regards,

                                                                                              Ken

                                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                          JohnDSiviter

                                                                                          Ken,

                                                                                          All the class-D ICs I have seen the datasheets of seem to give outlandish figures for power, only to find out at the back of the datasheet in on of their charts that distortion is in the double figures at anything approaching moderate. Do you see Class D as the future of audio amplification?, or do you see some other class/hybrid class becoming the standard in future audio amplification?.

                                                                                           

                                                                                          Regards,

                                                                                          John, Farnell Technical Team.

                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                              kdboyce

                                                                                              John,

                                                                                               

                                                                                              You have asked an excellent question, but the answer is not so simple.

                                                                                               

                                                                                              One of the principle reasons to use Class D audio is to generate large output power without having the power dissipation and heat generated by Class A, B, AB, G, and H audio amplifiers.  So Class D is a very attractive option.

                                                                                               

                                                                                              The often forgotten spec in audio is the infamous 10% distortion figure for output power.  This is an industry standard and is a common (almost required) spec point in all audio amplifiers.  You will find it in data sheets for practically all audio amps.  In case you didn't know, the 10% distortion figure is THD + N, or Third Harmonic Distortion + Noise,  and is the level at which most people will clearly notice that the sound is distorted somewhat.  This is because the 10% level is also the level where the output signal waveform tends to start clipping.

                                                                                               

                                                                                              Unless something else is radically wrong with the amplifier, the THD+N drops off as you lower the output power.   So the industry has a 1% distortion spec as well on amplifiers.

                                                                                               

                                                                                              I have heard some very good Class D amps but all were operating at 1% distortion level output power, or even less.

                                                                                               

                                                                                              For audiophile quality audio, most people will not choose Class D since they are sure (1) they can "hear" the distortion even at lower output powers, and (2) somehow Class D amplification will modify the sound vs. pure linear amplification, and some other reasons that are hard to prove technically. Kinda like gold plated audio cables sound better :>)

                                                                                               

                                                                                              As equipment becomes smaller and lighter, choosing linear amplification for audio is a hard sell due to lower efficiency and heat dissipation.  So.. increasingly, Class D is being chosen.  A good example would be the "bookshelf" type amplifier systems in the home versus the older larger equipment.

                                                                                               

                                                                                              A good example would be audio amps in thin TV's.   It is well known that if heat generating linear audio amps are close to the LCD screen, the color near that location can be slightly modified and noticeable.  Also, power supply requirements are bigger if those are linear, and they also generate heat.   Class D allows TV makers to put acceptable sound in a thin package.

                                                                                               

                                                                                              Cell phones and items of that type also benefit greatly by using Class D amps, even at 1W (1% THD+N) to 2W(10% THD+N).  In today's environments with large amounts of ambient noise, having higher output levels of sound is a good thing.  Some of the Class D  IC amps today have 10X the output power (10% THD+N) in the same die size as older linear amps at 0.5W.

                                                                                               

                                                                                              To avoid using Class D amps, designs have appeared using variations of linear amps - Class G, and H.  These types of amplifiers attempt (and succeed) to reduce power losses and heat generation by varying in some way the supply voltage to the amplifier based on the input signal level.  The higher the input, the higher the supply voltage is allowed to go, and vice versa.  But they do not match Class D in efficiency or heat reduction.  But they are linear and can have better power output at low THD+N.  Class G switches the supply voltage based on some input level or levels in multi-level Class G, while Class H tracks the input signal and changes the supply voltage accordingly.

                                                                                               

                                                                                              The other thing to remember is that Class D is not that beneficial at very low output powers.  An example would be headphone only amplifiers.  Most of these are linear, either capacitor output coupled, or direct coupled (+ and - supply voltages internally generated by a charge pump circuit).  Since the headphone or earbud is very close to the ear canal, any distortion and Class D switching noise would be easier to hear and be downright annoying.

                                                                                               

                                                                                              By the way, if you think datasheet high output power ratings are somehow misleading, try figuring out what Peak Music Power Output (PMPO),  Peak Envelope Power, RMS power, Sine power (the most reliable measure of the output power capabilities of an amplifier), DIN power (European standard) means when you see them on some consumer audio products.   An example would be a small bookshelf type speaker amp that offers 100W PMP when the amps clearly can only put out less than 10W Sine Power.

                                                                                               

                                                                                              I hope this answer helps you more than add confusion to the mix.

                                                                                               

                                                                                              Ken

                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                              JohnDSiviter

                                                                                              Ken,

                                                                                              I am wanting to get into Digital Audio, I have a good background in electronics from uni, but I did not take the Z-Transform option on my course!,  good basic information is sadly lacking on the internet, I would like to start from theory, like how I would go about replicating say a Butterworth Filter Digitally, I am also looking at dsPICs as an introductory way to get into DSP.

                                                                                              Any suggestions would be appreciated.

                                                                                               

                                                                                              Regards,

                                                                                              John. Farnell Technical.

                                                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                Natealmond

                                                                                                Ken:  Where can I get a circuit schematic of a digital, audio amplifier? Thanks

                                                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                    kdboyce

                                                                                                    Hi Nate,

                                                                                                     

                                                                                                    The term digital amplifier is one of those terms that can mean many things.  I prefer the following:

                                                                                                     

                                                                                                    All Digital Amp:

                                                                                                    This term means that the audio input to the amp is in digital form, usually via a recognized digital audio format like I2S, and that the output is operating in Class D mode where the output signal switches between the voltage rails (+ and - supply, or + supply and GND).  But basically it means that the amplifier should be able to take in digitized samples of the audio at some particular sampling rate, and thru internal means  modulate (usually pulse width modulation) the output switching waveform in some fashion such that IF you applied a low pass filter between the outputs and the speakers, the combination of low pass filter and speaker inductance/capacitance would convert the switching waveform to analog audio you can hear.

                                                                                                     

                                                                                                    Class D amp:

                                                                                                    This primarily means an audio amp where the output stage is operating in Class D (switching mode).  Some people refer to this as a digital amp.  But it is really a digital (switching) output stage.   The input can be analog audio, with the amplifier operating a particular A-D modulation scheme which results in the switching output or the input could also be digital as already described, depending upon the particular amplifier design.   Output filtering is general required except in relatively low power cases (generally under 5W, but new designs are pushing the envelope to ~15W) and where the amplifier is physically very close to the speaker (few inches)

                                                                                                     

                                                                                                    Of course there are amplifiers out there that take in digitized audio and do an internal D-A operation and operate the output stage in one of several continuous time analog Classes (A, AB, B) which do not require filterting on the output before the speakers.

                                                                                                     

                                                                                                    The amplifier you need would depend upon what your application is.  As I recall, your application was relatively low power, and so the amplifier would be chosen on the basis of what form your audio into will be.  If I know that, I might be able to recommend a single monolithic "digital" amplifier for you.  If you have a high power need, then that would be a different answer.

                                                                                                     

                                                                                                    Let me know (a) the format of the input audio, (b) the power level of the output, and (3) something about the final application.  Again, if I remember correctly, the application was related to hearing aids, but I don't know if it will finally be in-ear type, or some other form.    If in-ear,  the noise performance of whatever amplifier is chosen will be very important, along with the power consumption.

                                                                                                     

                                                                                                    Ken

                                                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                    Al@Mond

                                                                                                    Ken:   I wrote a lengthy response to your letter to me.  When I pushed "send" a message flashed saying I was unauthorized and then deleted my message.  That was very bad. Can you help rectify this.

                                                                                                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                        almond

                                                                                                        Ken: This is once again your ancient engineer Al Mond, who celebrated big nine-0 birthday this week, asking your advice.  Instead of trying to create and build my idea of a perfect complementary audio hearing aid, let me put the question of you.    Do you suppose it is possible to build an audio amplifier which  deletes all vowels and amplifies only the consonants?  The technical difference is that the vowels are all sinusoidal and the consonants are literally noise spikes.   There is a huge theory that goes with this and I am hoping to publish this in the New England Journal of Medicine.  But the bottom line is that hard of hearing people typically don't hear the consonants.  For one simple but important reason, the consonants are thousands of times quieter than the vowels, and considerably shorter in duration.  Give me your thoughts of the possibility of a consonants only audio amplifier.

                                                                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                            kdboyce

                                                                                                            Hello Nate,

                                                                                                             

                                                                                                            I hope your Thanksgiving was all it should be....with family and friends.  Also, CONGRATULATIONS on your 90th.  I hope I am still as inventive and interested as you are when I am 90.

                                                                                                             

                                                                                                            Nate....your question regarding an amplifier that only amplifies consonants and rejects vowels is way out of my league.  My natural response would be to say that you would need very sophisticated signal identification and  filtering to accomplish the task.   I personally don't know any techniques in analog signal processing that could do that job economically or with a high degree of programmability and repeatability (stability).

                                                                                                             

                                                                                                            I think you would have to resort to a digital signal processor programmed to recognize the audio type.

                                                                                                             

                                                                                                            The minimum HW in the DSP scenario is an A-D converter, the DSP, and then a D-A.  The processing requirements would dictate the power consumption overall.  Because it is mono voice being processed, the sample rates can be kept low, but to recognize the sound type on the fly will still need many calculations on each sample and its relationship to previous samples.

                                                                                                             

                                                                                                            I am sorry I am not much additional help to you at this point.   I know a couple of good DSP algorithm people, and next week I will pose the question to them and see what I get back.

                                                                                                             

                                                                                                            Kind regards,
                                                                                                            Ken

                                                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                          jia gao

                                                                                                          The  HCPL-5530HCPL-5530 is commercial grade two channel hermetically sealed optocoupler in a 8-Pin ceramic DIP package with gold plated leads Solder dipped leads and various lead form options are also available See datasheet for details
                                                                                                          The product is capable of operation and storage over the full military temp range and may also be purchased with MIL-PRF-38534 Class H or K level testing or from the DSCC SMD 5962-87679 The  HCPL-5530HCPL-5530 is manufactured and tested on a MIL-PRF-38534 certified line and Class H and K versions are included in the DSCC Qualified Manufacturers List QML-38534 for Hybrid Microcircuits
                                                                                                          Each channel contains a GaAsP LED which is optically coupled to an integrated photon detector. Separate connections for the photodiodes and output transistor collectors improve the speed up to a hundred times that of a conventional phototransistor coupler by reducing the base-collector capacitance.  http://www.seekic.com

                                                                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                            sukandar

                                                                                                            Hi, I'm looking for a single chip AGC solution for a microphone. So far I could find the MAX9814ETD+TMAX9814ETD+T, but don't like the TDFN package. SSM2216 and THAT 43xx are too expensive. Any other ideas? Thanks!

                                                                                                            • Re: Car- fuses, amps and audio whine
                                                                                                              croat_soldier

                                                                                                              Hi, I currently have a phone charger in my car (always on, even with ignition off) and I regularly use the audio feature. It suffers with extreme audio whining only when the ignition is on and alternates with acceleration (i'd guess because of the alternator).

                                                                                                               

                                                                                                              With a bit of research do I need a noise filter? Something like this? http://www.jaycar.com.au/productView.asp?ID=AA3074&keywords=noise+filter&form=KEYWORD

                                                                                                               

                                                                                                              However my phone charger requires an input of 12V 2A. Could i simple throw in a 2A fuse after the 10A DC Noise Filter? Also what sort of input would it require? (tapping in from the fuse box in the passenger side)

                                                                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                vikash.viks

                                                                                                                hi, i m a student persuing b.tech 2nd yr , i would like to have ur cooperation in d field of electronics to get best knowledge thank u.

                                                                                                                • Liquid Level Sensors
                                                                                                                  Coveyjhc

                                                                                                                  Does anyone know if there have been any equivalents manufactured for the National LN1042N or LM1830N

                                                                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                    hughfon1

                                                                                                                    There appears to be in existance an L7806cv but I do not find it on the order system

                                                                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                      passoutlaw3

                                                                                                                      I am a new member and wasn't sure to reply to ask a question... 

                                                                                                                      If they can fit tiny pixels into a phone making it a 1080 screen why is it taking so long to make 4k pixel tvs?

                                                                                                                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                        lisabellef

                                                                                                                        Hi,

                                                                                                                         

                                                                                                                        I am a design student at Carnegie Mellon University and am making a lighting project using LEDs where when two spheres come together one brightens and the other dims. I have purchsed 67C8928, 89F1394, 05M4554. Could you help me by telling me what else I need or how I might make this happen?

                                                                                                                         

                                                                                                                         

                                                                                                                        Your help is greatly appreciated.

                                                                                                                         

                                                                                                                        Lillie

                                                                                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                            kdboyce

                                                                                                                            Lillie,

                                                                                                                             

                                                                                                                            As I understand it you have purchased 2 proximity switches (the Hamlin parts - 05M4554 and 89F1394) plus the Silonex photocell 67C8928.

                                                                                                                             

                                                                                                                            The Hamlin parts are ON-OFF devices, while the photocell output varies with light intensity.

                                                                                                                             

                                                                                                                            You state that you want the LED to brighten in one sphere while the LED in the other sphere dims when the 2 spheres come close to each other.  

                                                                                                                             

                                                                                                                            Questions:

                                                                                                                            Do you want the LED that dims to go out? 

                                                                                                                            Do you want the LED light intensity in each sphere to change with distance rather than just dim or brighten when the spheres are close enough?

                                                                                                                             

                                                                                                                            Ken

                                                                                                                          • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                            SGoosman

                                                                                                                            This was supposed to be a question for something else that got posted here for some reason.

                                                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                              chris29a

                                                                                                                              Hi Ken, I need serious help! I am not sure if this is the right forum. I am not an electronic engineer just an older, non tech savvy guy in Sydney who heard on the radio that the Raspberry pi (Model B 520, 4GB SD Card) would convert my TV into a smart TV... ! All I want is to be able to play streaming video ( such as movies, ABC i-view and wiziwig.tv) on my computer (upstairs) through the LAN network to the pi connected to my Panasonic plasma TV downstairs to view it there.

                                                                                                                              Alternatively, if there is computer software which allows me to save streaming video to my computer, I could then transfer it manually via an SD card or disc straight to my TV and not need the pi at all... PS the geeky son of a friend was unable to help...

                                                                                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                dr.akshay_1980@yahoo.com

                                                                                                                                Hi Ken Boyce,

                                                                                                                                 

                                                                                                                                I want to know how to write firmware for chinese multimedia players(mp4/mp5 players) and make their binary files and how they are burn into the ROM from the manufacturer.

                                                                                                                                How these files are able to boot these players including soc chips from chinese manufacturers like sunplus,rockchip,jxd,...ARM926ej  is generally used in these portable players...

                                                                                                                                I want to customize these binary image files and want to play with these....kindly provide me players firmware knowledge and which is the development platform for these files?is it some kind of OS..?

                                                                                                                                Secondly how these players are able to decode all audio formats including mp3,wav,aac, is it software algorithm or the Soc ARM926ejs which is used is able to decode all formats efficiently and in other cases video formats of all types which are supported avi,wmv,flv,rb,webm... etc

                                                                                                                                complete reliable guidance/resource for this is appreciable in this regard...

                                                                                                                                thanks in advance

                                                                                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                    michaelkellett

                                                                                                                                    If you want to re-purpose one of these devices you have a lot of work to do.

                                                                                                                                    Somehow you will need to get the supplier of the chips to privide enough technical information but this won't be easy because there is no commerical reason why they should.

                                                                                                                                    There are open source re-coding projects for some routers  - you might get some idea of how it's done by studying them.

                                                                                                                                     

                                                                                                                                    One device:

                                                                                                                                     

                                                                                                                                    http://www.rock-chips.com/a/en/products/RK28_Series/2013/0730/331.html

                                                                                                                                     

                                                                                                                                    uses a built in DSP which would help the decoding.

                                                                                                                                     

                                                                                                                                    MK

                                                                                                                                      • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                        dr.akshay_1980@yahoo.com

                                                                                                                                        thanks Michael, for the page you reffered to me but my  concern is also about how these IMAGE files used for booting the hardware are able to run on what principles?is this a kind of OS which is able to boot without following basic principles of booting an OS and as far as DSP is concerned to decode the formats of all audio and video ,is it meant for specific formats or it's a general format decoder .In case it is then we can make DSP core in SoC which is able to decode all the formats available in the world whether its audio/video just like we need to convert files from wav to ma3 or other format supported by our player,generally we need flv to avi converter software to convert and then play desired files in my player. AMV format is common among these players....

                                                                                                                                        all of the work will be done by the hardware irrespective of the input format and all of the work will be done by the HARDWARE, no prior  format conversion with the help of software is required for this..

                                                                                                                                        bye

                                                                                                                                    • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                      joyceann57

                                                                                                                                      Hello, I am trying to put together a device that will allow me to communicate at the brain wave frequency, preferably in the 5 to 8 Hz range. Also, is the type of wave important (sine, square, or triangular)? I want to use this to help me to learn faster, study and remember better. I basically want to give myself instructions in the above categories. I purchased a raspberry Pi for this but I know I will need to add to it.

                                                                                                                                      Please help with this task.

                                                                                                                                        • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                          kdboyce

                                                                                                                                          Hello Joyce,

                                                                                                                                          The frequency range you mention is typical for Theta Waves of the brain although Alpha Waves at 8-12 cycles per second are also associated with "learning".

                                                                                                                                           

                                                                                                                                          Since the human ear does not normally hear such low frequencies, neuro stimulators create them as beat frequencies between two other higher frequencies.  Generally you would want to use sine waves but it does not appear critical that the sine waves are pure.  Approximate seems OK.

                                                                                                                                           

                                                                                                                                          You would need to generate 2 simultaneous frequencies, say 1KHz and 1.01KHz to get a 10Hz difference beat frequency which the brain may internally perceive.  But you would also get a 2.01KHz "beat" frequency as well.

                                                                                                                                           

                                                                                                                                          You would have to do a lot of experimenting to pick the best higher frequencies which will generate the desired low frequency beat tone. 

                                                                                                                                           

                                                                                                                                          Each frequency would have to be fed separately to the left and right headphone channels since to get the desired internalization of the low frequency - e.g. a binaural audio signal - not a stereo audio signal.  So aside from two frequency generators, you need two separate digital to analog converters as well as two separate audio amps.

                                                                                                                                           

                                                                                                                                          Have you given thought to using some existing apps that do binaural beat generation for your purpose, such as

                                                                                                                                           

                                                                                                                                          https://itunes.apple.com/us/app/brain-wave-30-advanced-binaural/id307219387?mt=8

                                                                                                                                           

                                                                                                                                          There are some similar ones for Android.

                                                                                                                                           

                                                                                                                                          Ken

                                                                                                                                            • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                              joyceann57

                                                                                                                                              Thank you Ken this was very helpful. I plan to make some changes later but this is a good start. I may need to clarify some things later with you.

                                                                                                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                                joyceann57

                                                                                                                                                Thank you very much Ken. I actually downloaded the Apple binaural beats. I have them on sometimes when I sleep. Ken I am also thinking about another project. I have been trying to find a way to help myself and others. I saw this situation where someone was using a cellphone hooked up to some sort of electronics and they were using it to manipulate others behavior, without the other person knowing. At first I didn't believe it, I thought the other person had a listening device. Then I saw it used repeatedly on other people just to prove it to me. I was shocked and have been trying to figure out how I can put this to good use for myself, but the person wouldn't show me HOW he was doing it. That's why I wanted to use the binaural codes but those are just sounds not words. I need help doing this, how do you think this is possible?

                                                                                                                                                  • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                                    kdboyce

                                                                                                                                                    Hello Joyce,

                                                                                                                                                     

                                                                                                                                                    Needless to say I  do not like any application that would deliberately set out to manipulate another person unawares.  So I would hope - and advise strongly - that you would not do that.  Aside from the unethical behavior of the act,  you have no way of knowing precisely  how the subject person might react.  That in itself can be dangerous since you might think you have control but you don't.  Even the party showing you this cannot guarantee the reaction of the subject no matter how smart he/she thinks they are in developing and using this type of application.

                                                                                                                                                     

                                                                                                                                                    From a technical point of view, the binaural sounds can be anything which when perceived subliminally by the brain would be one or more of several things:  noise, music, voice (think hypnotic commands), etc.  Obvious audible sounds would not work as the subject would know they are being used.

                                                                                                                                                     

                                                                                                                                                    I don't want to go any further than this.  Even if you try it on yourself, you can easily get into a situation where you no longer control yourself as you might think.   Experienced hypnotists have to be very careful to build in safe guards in what they say to a subject.  And even then some have problems with certain kinds of subjects.

                                                                                                                                                     

                                                                                                                                                    Take heed.

                                                                                                                                                    Ken

                                                                                                                                              • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                                dttech

                                                                                                                                                How does Mobile Data Work on the hardware level?

                                                                                                                                                • Re: Have a question about multimedia or audio? Ask our Expert, Ken Boyce
                                                                                                                                                  alexbl

                                                                                                                                                  Good Morning

                                                                                                                                                  I'm a 15 year old building an iPod dock for a school project I would be grateful if you could recommend an appropriate speaker

                                                                                                                                                  Thank You in advance

                                                                                                                                                  Alex B