Out in Front: November 9, 1995

Hewlett-Packard’s compact, portable 54615B digital storage oscilloscope (DSO), the latest member of the company’s popular 54600 series, is the first in the family to offer fast-real-time as well as random-equivalent-time sampling. Although the scope achieves its full 500-MHz bandwidth only in the random-sampling mode, it can sample both inputs simultaneously at 1G samples/sec. Bandwidth in the real-time mode is 100 MHz. Whereas acquisition memory depth is only 5k samples/channel, the scope offers an all-digital minimum/maximum mode that eliminates aliasing at low sweep speeds, at which the sampling rate might otherwise cause problems. In the minimum/maximum mode, the scope always samples at the fastest possible rate but retains only the highest and lowest values in the range of samples corresponding to an x-axis location. The display connects these two values with a solid vertical line. At 10 µsec/div, for example, each x-axis location represents approximately 200 samples.

Unlike HP’s other fast-sampling DSOs, the 54615B lacks waveform reconstruction, which would have allowed a higher single-shot bandwidth. The company says that it made this trade-off to optimize the unit’s responsiveness, which provides an analog-scope-like “feel” when you change the control settings. A proprietary three-processor architecture allows this key 54600-series attribute. The $6995 unit does not include a floppy-disk drive. HP claims that users who want a computer interface are happy with $485 and $765 add-on units that store many acquired waveforms; perform waveform math, including FFTs; and provide RS-232C, parallel, or IEEE-488 ports.
—by Dan Strassberg

Hewlett-Packard Co, Santa Clara, CA. (800) 452-4844.