HP 54540 Series - Page 83

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Record Length Softkey
Record Length Softkey
The record length softkey is available in the real-time mode only. The record
length softkey allows you to sets the memory depth for the waveform record.
The time between the sample points equals 1 divided by the sample rate, and
the amount of data in memory equals the time between the points times the
number of points. For example, if the sample rate is 2 GSa/s and the record
length is 512 points, the time between the sample points is 500 ps; and, 500
ps times 512 points is 256 ns of waveform data stored in the waveform
record, Because there are ten horizontal divisions, set the time base to
20 ns/div to display the most of the waveform record. To display the entire
waveform record, set the time base to 25 ns/div. To set the time base to
25 ns/div while the scope is running, set the sample rate to the adjust mode
and press the Fine key.
1 ; :
Sample Rate (Record Length) = Time Duration of the Record
Each channel has its own 32K waveform memory. The default setting is 512.
If you specify a 2K record, then each channel uses 2K of its available 32K
record. You cannot specify a different record length for each channel. For
single-shot applications, you may want to capture as much data as possible
by using a 32K record. You can pan and zoom through the data at a later
time. If you are not using pan and zoom, use a 512-point record, or use
enough memory so all of the data that is acquired on each acquisition is
displayed on the screen.
You can specify a record length from 512 points to 32,768 points with the
entry knob. Remember that sample rate and record length work together. If
you combine a short record length with a high sample rate, you will have a
very fast throughput, but very little data in the record.
Because the shortest record length is 512 points and the screen displays 500
of these points, there are 12 data points in the waveform record that are not
displayed at 50 ns/div and faster and in the auto mode (as per table 4-1). You
can use pan and zoom to view any data points that are not displayed.
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