To measure the on/off ratio
This assumes you have already set up time gating as in “To set up time
gating.”
1. Turn on averaging:
Press [
Average
], [
average on].
2. Turn on and zero the offset marker on the spectrum display:
Press [
A
], [
Shift
], [
Marker
], [
Shift
], [
Marker⇒
].
3. Move the gate to the “off” portion of the time display:
Press [
B
], [
Time
], [
ch1 gate dly
].
Rotate the knob until the gate markers encompass the “off” portion of the
signal.
The display should appear as below.
This measurement allows you to determine how much of the carrier leaks
through to the off portion of a burst transmission and therefore establishes
the dynamic range of the transmission system. In this particular example
the dynamic range is low because of the noise inherent in playing a signal
through the arbitrary source.
On the upper trace the offset marker is set at the “on” signal level.
When the gate is moved to the “off” portion of the signal,
the marker reading reflects the difference between the “on” portion
and the “off” portion of the signal.
Making On/Off Ratio Measurements
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