Stanford Research Systems SR780, Operating Manual And Programming Reference

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4-88 Trigger Menu
SR780 Network Signal Analyzer
Trigd Source Mode
Set the trigger mode for the source [1-Shot, Continuous]. The Chirp, Burst Chirp, Burst
Noise and Arbitrary sources are all triggered sources. This box is unavailable if the
source is not a triggered source.
Free Run Trigger Mode outputs the source continuously and ignores this menu box.
Triggering
The triggered sources are triggered by External triggers.
In the 1-Shot case, the source only triggers on the first trigger after [Start/Reset]. This
same trigger starts the measurement (and waterfall). This is useful when the source length
is very long compared to the measurement time or many measurements are required to
determine the response to a single source output. This allows a sequence of many
measurements to be triggered at the start of a single triggered source output.
In the Continuous case, the source triggers on every trigger, with a minimum trigger
period set by the source length (FFT time record, noise source period or arbitrary source
length). This is useful when the source length is the same as the FFT time record length.
Do not use Ch1 or Ch2 input trigger since the output will not start until a trigger is
received.
Source trigger outputs the source continuously over and over. FFT time records are
synchronized to the source start.
Watch Out For Triggered Sources
If a triggered source is selected (Chirp, Burst Chirp, Burst Noise or Arbitrary), the
triggered FFT measurement phase is stable only if the input signals are derived from the
source output. Turn the source off (or set it to Sine) when making triggered
measurements without the source.
Command: STMD (?) {i}
Manual Arm
Manually arm the trigger. This function only applies if the Trigger Mode is Manual Arm.
Manual Arm enables triggering after [Start/Reset] only after the trigger is armed using
<Manual Arm> or from an interface command. Once the trigger is armed, the next trigger
event will trigger the measurement.
For FFT measurements, each time record requires the trigger to be re-armed. For octave
and swept sine measurements, the first trigger after arming starts the measurement and
subsequent triggers are ignored.
Command: TARM