Each of the two channels can operate at up to 100 Msamples/s with a 32-kbit sample buffer. The 2102M includes a spectrum analyzer (FFT), advanced triggering, and pass/fail testing. It's able to capture single-shot data at 100 Msamples/s on two channels simultaneously, and it contains 32-ksample/channel buffers.
The 2102M has a number of triggering options. They include level trigger with rising or falling slope, TV horizontal, TV vertical, pulse count, trigger on the Nth pulse, pulse width, trigger on a pulse of a certain width, pulse width + count, and trigger on the Nth pulse of a certain width.
With its Autosetup of both channels, a single mouse click will cause the software to analyze incoming data and set up the DSO to capture the data. Rate, voltage/division, offset, and trigger level can all be preset, and then any of these parameters can be modified later.
Deep Acquisition Memory
The deep acquisition memory maintains fast DSO sample rates, even at slow timebase settings. The 2102M contains deep, 32-kpoint/channel data buffers, allowing it to record long data streams. Unlike short-memory DSOs, the 2102M maintains full 0.1% timebase accuracy and 10-ns sampling resolution on long 327-µs events or data streams. This means that it can accurately capture a 1-kHz signal containing up to 50-MHz frequency components—or a 60-Hz signal with 1-MHz glitches riding on top.
After recording the data, a "zoom-and-scroll" feature simplifies both troubleshooting and analysis of digital hardware/software problems and of long analog signals. The display shows the entire recorded waveforms. Also, the user can zoom in (up to 64X) on signal details and scroll through long data records to identify and characterize problems. The "locked all" channel zoom keeps all of the analog waveforms synchronized.
Furthermore, the deep memory lets the user analyze jitter from the beginning of the record to the end. By zooming/scrolling and then measuring with cursors, pulse widths and channel-to-channel timing can be compared at different sections of data streams. This feature enables identification of time-varying problems, such as "power-on" sequences and clock jitter.
The DSO-2102M provides high-accuracy spectrum analysis too. A binary FFT algorithm is used to break down the input signal into its spectral components. Unlike swept spectrum analyzers that require a stable, repetitive signal due to filter settling time, the 2102M can also analyze transient-event spectra. And, the user can control and view both the frequency-domain signal spectrum and its time-domain oscilloscope display, simultaneously.
The recording time of any DSO creates an acquisition window on the signal. It turns out that FFT spectrum analysis works best for transient signals that begin and end at zero, or for repetitive signals that can be depicted as an integral number of cycles within the acquisition window. An FFT analysis on other types of signals creates artificial spectra not present in the original signal. Shorter recording times and fewer spectral bins lead to worse errors. Most low-cost FFT analyzers provide no more than 512 spectral bins, whereas the 2102M offers up to 16,384 bins. This translates as 32 times better accuracy and fewer artifacts.
To further maximize spectral accuracy, the 2102M has five selectable "windowing" functions: Hanning, Hamming, Blackman-Harris, triangular, and rectangular functions. Also, the 2102M enables the user to store an unlimited number of waveforms, timing patterns, and spectra on a floppy-disk drives, hard disks, or PCMCIA cards. At a later date, designers can recall the stored data to the screen for viewing and for comparison with live data. Or instead, the stored waveforms can be processed through the 2102M's spectrum analyzer and waveform-analysis functions.
The 2102M includes software for DOS, Windows 3.x, Windows 95, and Windows 98. Software for winNT and win2000, which Link Instruments regularly upgrades, is available on the company's web site.
Compared to previous models, the latest generation of digital storage oscilloscopes includes a significant number of new features—no matter which model designers choose. Therefore, it's a good idea for engineers to familiarize themselves with these features and the terminology that comes with them (see "The Language of DSOs," p. 104).