Stanford Research Systems SR785, Руководство по эксплуатации и программированию

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Waterfall Menu 4-137
SR785 Dynamic Signal Analyzer
When All is selected the SR785 stores all the measurements in the current measurement
group to the waterfall buffer. This allows later viewing of any measurement, but uses up
more space in the waterfall buffer.
When Active Measurement Only is selected, the SR785 stores only the currently selected
measurement for each display. This takes less space in the waterfall buffer and allows a
higher value for Total Count, but only allows the currently selected measurements to be
displayed.
Command: WFSB (?) d{, i}
Total Count
Set the Total Count (number of records) to store in the waterfall memory for the active
display.
The maximum Total Count depends upon the allocated memory and the setting of Save
Option>. For example, if 500 blocks of allocated waterfall memory are allocated, and the
<Save Option> is set to Active Measurement each display will store 250 400 line FFT
measurements. If <Save Option> is changed to Save All the buffer will be able to hold
only 142 measurements. Changing frequency resolution may reduce the Total Count
since more buffer memory is required to hold measurements with higher resolution. .
The Total Count is limited to 2048 records (per display) regardless of the amount of
installed memory.
The rate at which measurement records are added to waterfall memory is set by the
Waterfall Skip. This allows the waterfall memory to hold a longer time history as well as
setting a variable storage rate.
Command: WTOT (?) d {, i}
Skip/Storage Interval
Set the Waterfall Skip/Storage Interval for the active display. The rate at which
measurement records are added to waterfall memory is set by the Skip/Storage Interval.
This allows the waterfall memory to hold a longer time history as well as setting a
variable storage rate.
The interval has no effect if Storage is Off. The Waterfall Display updates at the normal
rate for the display measurement and span.
In the FFT, Correlation, Order, and Time/Histogram groups, for every measurement
added to memory, a skip number of measurements are not stored. For example, a skip of
0 stores every measurement in memory. A skip of 10 stores every 11th measurement in
memory (store 1, skip 10). The skipped measurements are still computed and affect
(exponential) averaging, they are simply not stored. The elapsed time between stored
records (1/storage rate) is simply skip+1 times the FFT acquisition time times the time