HP 54522A - Page 82

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Sample Clock Softkey
Sample Clock Softkey
The sample clock softkey is available in the real-time mode only. Sample
clock (sampling rate) and waveform record length (waveform memory) are
closely tied together. Sampling rate determines how often the oscilloscope
samples the signal you are measuring. Record length is the amount of
memory the oscilloscope fills up before it updates the display and
measurement results.
Usually, you use a high sample rate, so there are plenty of data points to
better reconstruct the original waveform. For fastest throughput, use a short
waveform record because the oscilloscope must fill up the waveform record
before it updates the display and measurement results. The higher the
sample rate, the faster the waveform record fills up. Therefore, a long
waveform record slows down the throughput of the oscilloscope. As a result,
you must often make a trade-off between sample rate and record length to
achieve a desired throughput, both of which affect the measurement speed
and accurate reconstruction of the waveform.
You may prefer to sacrifice measurement throughput by selecting a high
sample rate and a long record length, or you may want to have a high sample
rate and a short record length to maximize the measurement throughput.
Auto
Auto lets the oscilloscope select the sampling rate for you. The advantage is
that the oscilloscope selects a sample rate that optimizes the way the
waveform is displayed and the display update rate.
Adjust
Adjust lets you specify a sample rate. The maximum sample rate is always
available to you regardless of the time/div setting. However, do not overlook
the interaction among sample rate, record length, and measurement
throughput. Also, when in the adjust mode, you can use the fine mode to
adjust the time base range to values not in the normal 1-2-5 sequence.
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