Stanford Research Systems SR785, Operating Manual And Programming Reference

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1-38 Waterfall Display
SR785 Dynamic Signal Analyzer
Press <Manual Trigger> <Manual Trigger> supplies the first trigger. The
source outputs a single noise burst (Trigd Source
Mode=One Shot). The display starts a continuous
stream of octave measurements, each linear
averaged for 8 ms and each starting when the
previous average is complete (Linear Avg
Mode=Continuous).
50 averaged measurements are stored in the
waterfall buffer starting with the trigger. The first
96 ms (12 measurements) are during the triggered
noise burst. The remaining measurements are taken
after the noise burst turns off and measure the
decay response or reverberation.
The number of records stored in the waterfall is
shown in the Vertical Scale Bar as ‘wf 50’.
11. Press [Alt] and turn the knob clockwise.
Continue until the display does not scroll any
further.
[Alt] knob moves the marker in the Z direction
(time axis) in the waterfall display. This scrolls the
display to show earlier measurement record.
When the keypad and knob are in the alternate
mode, the alternate key functions (labeled below
each key) are in effect.
The waterfall records are numbered starting with 0
(the most recent measurement) in the back. In this
case, we stored 50 records so the earliest record is
number 49.
The marker Z position is displayed next to the
marker frequency in the Marker Position Bar above
the graph. It should read ‘49’ when you have
scrolled all the way to the beginning of the buffer.
Notice how the first few records show the spectrum
growing at the start of the noise burst The low
frequency bands grow more slowly than the high
frequency bands because their filters have longer
time constants..
Press [Alt] Pressing [Alt] removes the keypad and knob from
the alternate mode.
Turn the knob clockwise to move the marker
along the frequency axis of a single record. The normal knob function moves the marker along
the X axis of a single record.