You need to test, we're here to help.

You need to test, we're here to help.

15 April 2015

Testing Challenges in Motor Drive Systems (Part II)

Yhe complete design and debug challenge posed by a variable-frequency motor drive
Figure 1: This image depicts the complete design and
debug challenge posed by a variable-frequency motor drive
In our first post on motor drive systems, we broke down the major subsystems in a "generic" variable frequency drive (VFD) and discussed some of the test requirements in those subsystems (Figure 1). Next, let's have a look at some of the variations in real-world VFDs in terms of architectures and topologies.

07 April 2015

Testing Challenges in Motor Drive Systems

The power section of a motor drive system requires measurements of line input, PWM output, and efficiencies
Figure 1: The power section of a motor drive system requires
measurements of line input, PWM output, and efficiencies
Motors are everywhere in our world, and nowhere more so than in  our vehicles. For example, when's the last time you had to crank a car window up and down to pay a highway toll? Or, for that matter, when did you last manually adjust the seat position or rear-view mirror angles? These aspects of vehicles are all typically motorized these days.

02 April 2015

The History of Jitter (Part III)

Latching a signal at the outermost of the blue hash marks results in a BER of 10-3, while latching it at the innermost hash marks yields a BER of 10-12
Figure 1: Latching a signal at the outermost of the blue
hash marks results in a BER of 10-3, while latching it
at the innermost hash marks yields a BER of 10-12
If you've been keeping track of our history of jitter, we left off in Part II in the late 1990s, by which time bit-error rates (BER) had become a predominant statistic for quantifying jitter. That was subsequently refined into thinking in terms of BER as a function of jitter.

27 March 2015

Back to Basics: Choosing an Oscilloscope

An oscilloscope such as Teledyne LeCroy's HDO6054-MS serves a very broad range of applications
Figure 1: An oscilloscope such as
Teledyne LeCroy's HDO6054-MS
serves a very broad range of
applications
Choosing an oscilloscope might seem to be a challenging task, but it doesn't have to be. Rather, it's a more-or-less logical process based on your measurement needs. Having said that, if the application for the instrument is "general lab work," the decision can become trickier.

20 March 2015

Using Histograms (Part III)

A simplified view of a push-pull amplifier showing the source of crossover distortion
Figure 1: A simplified view of a push-pull amplifier
showing the source of crossover distortion
In this third post in a series on using an oscilloscope's histogram capabilities, let's take a look at using histograms as a diagnostic tool. Diagnosing problems in a circuit calls for good skills and some intuition on top of good measurement tool. In general, though, the more ways in which you're able to look at a problem, the more likely it is that you'll turn up the root cause.

12 March 2015

The History of Jitter (Part II)

An example of using histograms to plot the statistical distribution of edge arrival times
Figure 1: An example of using histograms to plot
the statistical distribution of edge arrival times
Resuming our review of the history of jitter and the evolving response to it, we'd arrived at the late 1990s, when more sophisticated analysis methods were necessary to get a good handle on jitter. In particular, statistical analysis came onto the scene. Statistics are a great tool for analyzing phenomena such as jitter that change more as you look at them harder.

05 March 2015

The History of Jitter

The story of jitter spans 45-baud telegraph machines to 160-Gbaud optical fiber
Figure 1: The story of jitter spans 45-baud telegraph
machines to 160-Gbaud optical fiber
Jitter is a signal-integrity gremlin that's been with us for a long time. In fact, it's been with us since before anyone really needed to care about it. But as time has worn on, our perception of jitter has certainly changed, and with it our approaches to diagnosing it, measuring it, and ultimately dispatching it. Here, we'll begin a traversal of the "jitter story," surveying where we've been, where we are, and where we may be going in our dealings with the phenomenon.