Product specifications

Setting up pulsed-RF measurements continued

Step 2 Synchronize data acquisition and pulses

With internal pulse generator option, pulse trigger feature is added to the PNA-X

trigger system (Figure 10b Pulse Trigger tab on Trigger dialog). Specify trigger

source – either internal or external (incoming pulses to PULSE SYNC IN) and

check “Synchronize receiver to pulse generator Pulse0”. Note that measurement

trigger (MEAS TRIG IN port on PNA-X rear panel) is not used in typical setup.

Step 3 Adjust data acquisition time

Set IF bandwidth to be wider than at least 1/(pulse width), in order to complete

the data acquisition while pulse is on. For example, 10 s pulse width requires at

least 100 kHz IF bandwidth or wider. It is recommended checking Pulse0 width

is smaller than the pulse width of modulation drive on Pulse Generator Setup

dialog. Recommended setting is to a step wider IF bandwidth than the narrowest

possible bandwidth for the given pulse width so that numerous system delays

do not cause a problem. The PNA-X, to account for the test port coupler roll-

off at low frequencies, adjusts IF bandwidth automatically and maintains the

measurement accuracy. This causes a problem in pulse measurements using

wideband detection method. Turn off “Reduce IF Bandwidth at Low Frequency”

on IF Bandwidth dialog.

For pulse profile measurements, the basic steps stay the same as point-in-pulse

measurements, but add slightly more complexity. The sweep type must be CW

Time sweep. The IF bandwidth needs to be much wider than the one for point-

in-pulse at the same pulse width. This is because pulse profile often requires

minimum 10 or more measurement points in a pulse compared to only one point

in a pulse with point-in-pulse. Define the IF bandwidth to achieve desired timing

resolution. In order to display the whole pulse profile, adjust number of points

and the delay for the modulation drive.