A Short Overview
First I would like to express thanks to Keysight/Agilent and Texas Instruments for selecting me to review the N9322C spectrum analyzer and CC11XLDK-868-915 Value Line Development Kit. I feel fortunate and honored to be one of the three people selected for this roadtest. I would also like to thank Element14 for organizing this roadtest.
N9322C belongs to the product category of basic spectrum analyzers and covers frequencies from 9kHz up to 7GHz. Besides addressing the primary frequency domain measurements, with built-in options N9322C can be used for signal modulation analysis like AM demodulation and listening through a built-in speaker, FM demodulation and time-domain display of demodulated signal, and ASK/FSK modulation analysis that can display the symbols, waveform, error, and eye-diagram. With the reflection measurement option, N9322C can be used to characterize transmission line cables and antennas by measuring reflections, one-port cable loss, and distance to fault.
The Texas Instruments CC11XLDK-868-915 development kit comes with two SmartRF transceiver boards on which users can plug various modules that can be used to evaluate TI’s sub-1GHz products: CC110L, CC113L, CC115L (included in the kit), and more others like: transceivers (CC1121, CC1200, CC1120), transmitters (CC1150, CC1175), and system-on-chip (CC430, CC1110, CC1111, ). The accompanying SmartRF Studio 7 software (that can be downloaded from TI website) can be used with the CC11XLDK-868-915 development kit to control and test the RF performance of the TI’s sub-1GHz products mounted on the modules. The SmartRF Studio software works also with 2.4GHz system-on-chip products.
First Impression After Receiving the Products
TI CC11XLDK-868-915 Value Line Development Kit
My TI Kit CC11XLDK-868-915 came first packaged in a small box (270x180x100mm as written on a label). Enthusiastic to start working on this roadtest, I opened the box and I took out the contents. Here is a picture of what was inside:
Included in the kit there was this instructions document on how to access the Texas Instruments website for technical support and downloading software:
Another useful document was a quick start guide, shown below, which helped me setup a transmitter/receiver link smoothly and in a quite short time.
Next step was to examine the boards, so I started with the two SmartRF TRXEB. The top side has a TI MSP430 microcontroller, a debug interface connector for the MSP430, an LCD display, four push buttons to navigate through the control menu displayed on the LCD, a USB connector, four LEDs, and multiple switches for selecting the functionality modes. On the upper right corner there are two connectors for plugging one of the evaluation modules (CC110L, CC113L, CC115L). Here is a picture of the top side:
On the bottom side there are two battery holders for AA type batteries. Batteries are included in the kit, but the boars operate without batteries if connected through a USB cable to a computer. Here is a picture of the bottom side of the board:
The kit comes also with a debug interface module for the MSP430 microcontroller, which I am showing in the picture below:
The debug interface can be connected to the SmartRF board through a supplied cable.
The four modules included in the kit are shown I the figure below:
One module has mounted a CC115L transmitter, another module has a CC113L receiver, and the other two modules have CC110L transceivers. Each module has an open pad for mounting an SMA connector which can be connected to an external antenna (instead of using the built-in antenna on the module PCB).
Agilent N9322C Spectrum Analyzer
The spectrum analyzer came in a large box with padding for protection. Here are some pictures of the N9322C spectrum analyzer after I took it out of the package:
The N9322C spectrum analyzer came with a certificate of calibration:
In the box I have also found two bags with accessories, which I am showing in the pictures below.
Besides the documentation CD, cables and adapters there was a N9311X-201 OSL precision mechanic calibrator, and a Diamond RH799 70 to 1000MHz wide-band antenna.
Setting up the TI evaluation boards
After unpacking the contents of the boxes I continued with setting up the TI kit. I plugged the CC115L transmitter module in one of the SmartRF boards and the CC113L receiver in the other SmartRF board. Before connecting the boards to the computer through the provided USB cables I went on TI website and I downloaded the SmartRF Studio 7 software and the USB drivers. First step on TI website was to create an account so I could then get access to the support documents. When I got to the support website for the CC11XLDK-868-915 kit I was impressed of how many technical documents are available to users. Here is a screenshot of only part of what they have:
And here is a screenshot of the SmartRF Studio download page:
My first attempt to install the drivers was not successful, but that was just my fault. After poking around a few times I noticed a switch on the SmartRF board pointing to UART (this was the default). I switched it the other way towards “SmartRF”, I plugged the USB cable in the computer, and the USB drivers got installed.
Next I installed the SmartRF software without any difficulties and I started it. Here is a screenshot showing the features of this software:
In learning how to use this program I found very useful the document “SmartRF Studio 7 Hands-on User Guide and Tutorial”
The SmartRF Studio 7 starting screen shows all the evaluation modules that can be controlled with this software, and out of those the ones that are connected to the computer are highlighted and listed at the bottom window:
Next I double clicked on CC113L and CC115L, which opened the control panels for these two modules. There are two modes of operation: an easy mode that has predefined register values and packet date and an expert mode that provides full control of the RF devices. Here is a screenshot of the transmitter and receiver control panels in easy mode operation:
And below is a screenshot of the transmitter and receiver control panels in expert mode of operation.
In expert mode there is a full description of each register and users can read and write any register.
A Few Experiments and Measurements
For my first measurement I have chosen to transmit an unmodulated continuos signal and measure it at receiver using the SmartRF signal measurement function, as I am showing in the screenshot below. Looking at the displayed receiver waveform, the level was at –120dBm before I started the transmitter and moved up to –28dBm after the transmitter started emit the RF signal.
For next measurement I connected the Diamond RH799 wide band antenna to the RF input of the N9322C spectrum analyzer. The antenna has 50Ohms impedance that matches the N9322C input impedance, and matches the characteristic impedance of the interconnect cable. The antenna captured the transmitted signal and sent it to the RF input of the N9322C spectrum analyzer. Here is a picture of this measurement setup:
Next I used the peak search function of the N9322C spectrum analyzer to find the amplitude and frequency of the peak TX carrier frequency. Here is a picture of the N9322C display showing the peak search/measure function:
On this screen we can see that the received carrier signal has a level of –21.78dBm and the frequency is 867.3MHz. The –21.78dBm is higher than the –28dBm signal level at the CC113L receiver on SmartRF board displayed on the control panel of the SmartRF Studio that I have shown in a picture above. The carrier frequency measurement of 867.3MHz is close to the 867.999939MHz carrier frequency programmed in the CC115L transmitter control panel.
Next, I wanted to see how the N9322C spectrum analyzer can show a demodulated signal, so I turned on the modulation in the CC115L control panel of SmartRF software, and I setup the TX to send a random packet in GFSK modulation format. Here is a screenshot of the CC115L control panel in this experiment:
Next I setup the N9322C spectrum analyzer to modulation analysis by pressing MODE -> Modulation Analysis -> FSK. In modulation analysis mode, the Agilent N9322C spectrum analyzer displayed the demodulated signal, as I am showing in the picture below:
After these measurements I took one of the CC110L transceiver modules and I installed an SMA connector in the available open pad, which allowed me to connect it to the N9322C spectrum analyzer directly through a coaxial cable. Besides mounting the SMA connector I had to move a capacitor to disconnect the on-board antenna and connect the CC110L output to the SMA connector. Here is a picture of the modified board.
I then replaced the CC115L TX module on the SmartRF board with this modified CC110L module and I setup the TX mode in continuos unmodulated transmission mode. With this setting the N9322C spectrum analyzer measures the carrier signal of the transmitter without any modulation. Here is a picture of this test bench setup:
Then I have setup the Agilent N9322C spectrum analyzer to measure the transmitter power by pressing Meas -> Channel Power buttons on the front panel. Here is a picture of the display showing the measured power.
The measured channel power was –0.04 dBm which is close to the transmitter power set in the SmartRF control panel of 0dBm. The measured power spectral density was –63.05 dBm./Hz.
The next measurement in this series of characterizing the transmitter was to see how temperature affects the TX carrier frequency. Agilent N9322C spectrum analyzer has a built-in function that tracks the signal drift. Here is a picture of the display showing the spectrum monitor on the upper part of the screen.
After setting up this measurement I took a hair dryer and I heated up the transmitter (oscillator crystal and CC110L transceiver integrated circuit). With this heat source turned on, the TX carrier frequency started to shift gradually as I am showing in the following picture.
Notice the bending of the spectrum monitor red line that shows the frequency drift in time as the temperature of the TX module increased. I have also captured this frequency drift in a video that I have linked blow:
This concludes the first set of measurements that I have done with the Agilent N9322C spectrum analyzer on the Texas Instruments CC11XLDK-868-915 development kit. I will come back with additional blog posts as I advance more into this roadtest characterization process and I run more experiments.