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This article presents information on the working of modern, high-performance digital oscilloscopes. Oscilloscopes offer a wealth of features for making users' lives easier--so many features, in fact, that their effect can sometimes be the opposite of what the manufacturer intended. Unlike real-time-sampling scopes, sequential-sampling scopes intentionally undersample their input signals--that is, they sample them at much less than twice the frequency of the highest frequency significant-amplitude component. In many such scopes, the sampling circuit is in a sampling head external to the scope mainframe.

This article presents suggestions in choosing digital oscilloscopes to be used in high-speed serial-bus debugging. For users to avoid outdated procedure, ensure that a new version of the help file or the file that sets up the scope is downloaded and installed. Real-time sampling scopes should sample many times than the highest frequency present in input signals to avoid aliasing. An important thing to be considered is determining how much bandwidth is needed. Another thing to be considered is the appropriate differential active probe.

The article offers news briefs related to test instruments in 2010. The scopes of WaveMaster 8Zi-A from LeCroy Corp. are upgradable to a maximum 45 gigahertz (GHz) in bandwidth from 4 GHz. The Infiniium 90000 X-Series oscilloscopes from Agilent Technologies Inc. promises to meet engineers' needs working with emerging wireline communication standards. The National Instruments Corp. NI PXIe-5630 brings support to complete vector analysis of transmission and reflection parameters.

The article provides information on data measurement and analysis of Nyquist sampling theorem. To obtain useful data, an engineer must sample a sine wave at more than twice its frequency. Further, for a more precise interpretation of the Nyquist theorem, he or she must sample at more than twice the frequency of the signal's bandwidth.

Features the portable digital oscilloscopes DL1700E Series from Yokogawa introduced in the British market in December 2004. Resolution bandwidth of the oscilloscopes; Points of memory per channel; Size of the oscilloscopes.

Tektronix Inc. has introduced a modular sampling oscilloscope--the TDS8200. The company also introduced the 82A04 phase reference module. The oscilloscope can be configured to provide bandwidth to 70GHz, and has a single-ended and differential clock recovery system covering all current and emerging serial data standards between 50Mbit/s and 12.6Gbit/s. System jitter is less than 200 femtoseconds at these data rates. The TDS8200 also provides the ability to measure random and deterministic jitter.