Understanding Probe Calibration Methods

If there's a topic concerning probes that causes confusion, questions, and misunderstandings, it's loading. It would be a much simpler world if attaching a probe to a circuit under test had no effect on either the signal being measured or the device the probe is connected to. Unfortunately, the world isn't quite so simple.

Making Sense of Probe Terminology

As oscilloscope users, we know that the probe is a critical element in getting signals from the device under test into the instrument. The ideal probe would have perfectly flat magnitude response and perfectly linear phase response across its entire frequency range. Unfortunately, that probe, though striven for by all oscilloscope manufacturers, does not exist.

Why Should You Measure Jitter?

Figure 1: Designing a serial-data channel with first-pass
success means analysis and mitigation of jitter sources

As mentioned in an earlier post on some basics of jitter, the bane of serial-link design is a signal that doesn't arrive at its destination when it should, whether early or late. The goal of serial-link design and implementation is to transmit data with as few bit errors as possible. Thus, analyzing jitter is a key element of achieving first-pass design success.

Tips and Tricks: Stabilizing a Waveform Trace

One initial challenge to oscilloscope users is achieving a stable display of an input waveform. In almost all cases, the Auto Setup button on Teledyne LeCroy oscilloscopes (and most other modern instruments) will automatically set the oscilloscope's triggering system to get that jumpy trace to settle down.

The Components of Total Jitter

Figure 1: An overview of the jitter hierarchy,
or "jitter tree," showing the various elements
that make up total jitter

In an earlier post, we began looking at the topic of jitter, a topic of keen interest to anyone working with high-speed serial communications or the components of such a system, including transmitters, receivers, and data channels. To gain an understanding of jitter, an important first step is getting to know a little about the various categories that comprise total jitter.

Mr. Oscilloscope, Meet Mr. Computer

Figure 1: WaveStation software enables full remote
control of an oscilloscope from a Windows PC

Some things just seem made to go together, such as peanut butter and jelly, baseball and hot dogs, and Lennon and McCartney. But in the engineering world, one great combination is the oscilloscope and the PC. Both are wonderful tools but together they go places that neither can without the other.

Let's Get Serial: About Manchester Data Encoding

Figure 1: An example of Manchester coding

Founded by the Roman Empire in the first century AD, the city of Manchester, England is probably best associated today with the Manchester United Football Club of neighboring Old Trafford. But in serial-data circles, the city's name evokes Manchester line coding, or phase encoding.