Keysight EXG and MXG X-Series Signal Generators User’s Guide
205
Basic Digital Operation (Option 653/655/656/657)
Using Waveform Markers
ALC Hold Marker Function
While you can set a marker function (described as
Marker Routing
on the softkey label) either
before or after you set marker points (
), setting a marker function before setting marker
points may cause power spikes or loss of power at the RF output.
Use the ALC hold function by itself when you have a waveform signal that incorporates idle periods,
burst ramps, or when the increased dynamic range encountered with RF blanking (
) is not
desired.
The ALC hold marker function holds the ALC circuitry at the
average
value of the sampled points
set by the marker(s). For both positive and negative marker polarity, the ALC samples the RF output
signal (the carrier plus any modulating signal) when the marker signal goes high:
Positive:
The signal is sampled during the on marker points.
Negative
The signal is sampled during the off marker points.
Because it can affect the waveform’s output amplitude, do not use the ALC
hold for longer than 100 ms. For longer time intervals, refer to
Incorrect ALC sampling can create a sudden unleveled condition that may
create a spike in the RF output, potentially damaging a DUT or connected
instrument. To prevent this condition, ensure that you set markers to let
the ALC sample over an amplitude that accounts for the higher power
levels encountered within the signal.
Positive
