7
3. PULSE TRAIN
Demo: with:
DOX2025
DOX2040
DOX2100
DOX2xxxB
Test Signal
n°3 : Pulse train
Nature
1 signal containing trains of 10 pulses with variable spacing
Specs
Vpp ≈ 3.4 V - F ≈ 32 kHz - Train spacings ≈ 100 to 180 µs
Oscilloscope Settings
100 µs/div. - CH1 = MAIN = 500 mV/div
Trigger
on CH1 = MAIN - Hold-Off ≈ 354 µs
Modes
Triggered mode preferable
Objective
Triggering with «Hold-Off» on pulse trains
a) Adjust the oscilloscope to display the signal on CH1 correctly (time base, sensitivity, and triggering source).
Attention, with this type of signal, “Autoset” operation may be aleatory.
Without “Hold-Off”, the triggering may act on any pulse of the train, as soon as the oscilloscope is ready to acquire. This is
accompanied by a feeling of “horizontal instability”, making the display unusable. The proper setting of the “Hold-Off” parameter (in the “Triggering”
menu
“Set”) serves to ensure systematic triggering on the first pulse of the train.
This value must be greater than the duration of the pulse train, to disable triggering during this period, but must remain shorter than the time between
2 pulse trains (which varies between 400 and 480 µs). In our case, the “Hold-Off” must be between 300 and 400 µs.
b) Definition of the mask of the “Pass/Fail” function. “Utility”
Pass/Fail
Mask Config
Mask Generation
c) Activation of the Pass/Fail function
The Pass/Fail function displays the number of times that the signal has satisfied (“Pass”) or not satisfied (“Fail”) the mask defined.
