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Teledyne LeCroy

23 posts
Now that we have a better understanding of what's happening under the hood of a 10x passive oscilloscope probe, we can sum up its key characteristics. The first thing to know about such probes is that they offer relatively low bandwidth (<100 MHz). This is largely a result of the probe's tip inductance.   A 10x passive probe is going to exhibit a relatively low signal-to-noise ratio (SNR). For one thing, you give up 20 dB in SNR simply due to the fact that the probe attenuates the measu ...
We've been discussing the ubiquitous 10x passive probe here on Test Happens, beginning with an overview of the probe-oscilloscope system. We turned to the 10x passive probe itself and the issues posed by its constitutive circuitry. Then we covered what about that circuitry makes it usable at all, namely, its built-in equalization circuit.   Figure 1: With unequal impedances at either end of the coax, are cable reflections a concern in 10x passive probes?   Now we'll consider anothe ...
If you're using 10x passive probes with your oscilloscope, it's important to understand the bandwidth of your probing system and how it's affected by various methods of probing the signal of interest. There's a relatively easy way to determine this parameter by probing a fast-edge, 10-MHz signal from a square-wave generator. Doing so can also instruct us in the effects of tip inductance on the probe's bandwidth.   When you look at the frequency spectrum of that fast-edge signal, you'll fin ...
We've been discussing 10x passive probes and their inner workings; our last post covered all the ways in which a 10x passive probe is apt to be a liability. They'd be basically unusable for any measurements at all but for one attribute: their equalization circuit (Figure 1). Without it, the 10x passive probe makes a pretty good low-pass filter, but the equalization circuit counters that with a high-pass filter to balance things out.   Figure 1: The adjustable equalization circuit on the ...
We began this series of posts on oscilloscope probes by putting them in perspective: Probes have a number of different jobs to do, including serving effectively as both a mechanical and electrical interface. Despite having electrical attributes of their own, we want them to grab our signal of interest, but we don't want them to affect that signal in any way.   In fact, we'd like our probe-cable-oscilloscope measurement system to be perfect, possessing: A mechanical interface that conforms ...
Few aspects of using an oscilloscope are as important as the probe: after all, the probe forms both the mechanical and electrical interfaces between the device under test (DUT) and the oscilloscope itself. To feed a signal into an oscilloscope, we're limited to a coaxial connection. Thus, we need a geometry transformer that picks up the signal of interest from the DUT and transfers it to the oscilloscope's coaxial connection.     Figure 1: Probe, cable, and oscilloscope form a syste ...
Our last post considered some broad aspects of debugging DDR memory on Internet of Things (IoT) devices, such as how chip interposers can help with probing access and the benefits of virtual probing software. Let's now take a look at some particular examples of problems with these memory chips and their controllers and see how debugging with an oscilloscope might be approached.   Figure 1: Using the oscilloscope's Track math function can help pin down timing anomalies   Figure 1 is ...
Internet of Things (IoT) devices are, at heart, just another embedded computing system, albeit one with an extremely well-defined function. As such, there's bound to be some amount of on-board data storage, and the storage medium of choice these days is typically double data-rate (DDR) memory. DDR memory transfers serial data on both the rising and falling edges of the clock signal, which is the characteristic from which it derives its name.   Figure 1: Embedded systems such as IoT devic ...
Figure 1: A generic IoT block diagram shows serial-data links in blue   In our ongoing review of debugging serial-data standards for Internet of Things (IoT) devices, let's now turn to three more popular protocols: Ethernet, SATA, and PCIe. Ethernet is found in computer networking applications, while the Serial Advanced Technology Attachment (SATA) connects host bus adapters to mass-storage devices. The Peripheral Component Interconnect Express (PCI Express or PCIe) handles communication b ...
A myriad of serial-data standards come into play when we're discussing Internet of Things (IoT) devices. We've talked about I2C, SPI, and UART in a previous post. Yet another serial-bus standard that comes under the IoT umbrella is the Controller Area Network (or CANbus) standard. CANbus enables microcontrollers and peripheral devices to communicate with each other in applications without an intervening host computer. In the past, it's been typically used in automotive applications, but CANbus h ...
Our last post discussed the difficulties in acquiring the many sensor signals that may be input to a deeply embedded system such as an IoT device as well as a hardware solution to the problem. Another aspect of IoT debugging and validation is the low-speed serial data standards used to facilitate communication between ICs and between controllers and peripheral devices (Figure 1). To that end, let's take a look at three such low-speed standards: I2C, SPI, and UART. Figure 1: Serial-data links ...
If we recall our earlier post with its definition of what constitutes an Internet-of-Things (IoT) device, one of the main functions of such devices is to sense its environment and digitize the collected data. Often, an IoT device uses many sensors to collect information about its environment (Figure 1). Having the ability to capture and analyze signals from numerous sensors simultaneously is critical to ensure proper and optimal functionality of the IoT device's design.   Figure 1: IoT d ...
Internet of Things (IoT) devices must communicate with their peers--other IoT devices--as well as with the host system that governs their activities. In our previous post, we examined how to perform amplitude and frequency demodulation of RF bursts, such as Bluetooth Low Energy (BLE) advertising bursts. We'll continue with other methods of analyzing RF signals. Figure 1: This screen capture depicts frequency demodulation and subsequent Manchester decoding of the bit stream   Figure 1 de ...
Debugging and validation of the physical layer of serial-data links is a preeminent oscilloscope application area these days. Today's real-time digital oscilloscopes have a wealth of tools to help you dig into any/all serial protocols and learn what's really going on electrically with your serial links.   Figure 1: Trigger dialog boxes will match the protocol of interest   First and foremost is serial triggering and decode. When appropriately equipped, Teledyne LeCroy oscilloscopes ...
Parameter math functions are an important part of an oscilloscope's analysis capabilities. Using parameter math, you can create custom parameters based on simple arithmetic relationships between existing parameters. It allows you to add, subtract, multiply, divide, or rescale parameters (Figure 1).   Figure 1: Parameter math functions provide a way to create custom parameters   You can do things like inverting waveforms, multiply voltage and current to find power, or integrate a wa ...