PMX40 RF Power Meter – INSTRUCTION MANUAL
3-9
The measured result is the average power of the signal. Since the graphic display would basically just
show a straight line, measurements in Continuous mode are best viewed using the Text Display mode.
Figure 3-5 shows a two-channel measurement displaying an average, minimum, and maximum power in
Continuous mode.
Figure 3-5. PMX40 Text Display Mode Using Continuous Measure Mode
3.5.2
Pulse Mode
For periodic or pulsed signals, it is often necessary to analyze the power for a portion of the waveform,
or a certain region of a pulse or pulse burst. For these applications, the PMX40 Series has a triggered
Pulse mode.
The trigger signal can be either internal, triggered from a rising or falling edge on the measured signal;
or external, triggered from a rear-panel BNC input. The trigger level and polarity are both
programmable, as is the trigger delay time and trigger holdoff time. Displays of both pre- and post-
trigger data are available, and an auto-trigger mode can be used to keep the trace running when no
trigger edges are detected. An ―auto peak
-to-
peak‖ trigger level setting can be chosen to automatical
ly
set the trigger level based on the currently applied signal. The timebase can be set from 5 ns/div to
50 ms/div. The PMX40 graphical display has 10 horizontal and 8 vertical divisions. Vertical units can be
set in dBm, Watts, and dB Volts. Setting vertical resolution does not affect the sensitivity of the
instrument and is provided for ease of viewing.
Programmable markers can be moved to any portion of the trace that is visible on the screen, and these
can be used to mark regions of interest for detailed power analysis. The instrument can display power
at each marker, as well as average, minimum, and maximum power in the region between the two
markers. This is very useful for examining the power during a TDMA or GSM burst when only the
modulated portion in the center region of a timeslot is of interest. By adjusting trigger delay and other
parameters, it is possible to measure the power of specific timeslots within the burst. Trigger holdoff
allows burst synchronization even if there is more than one edge in the burst that may satisfy the
trigger level. Simply set the holdoff time to slightly shorter than the burst’s repetition interval to
guarantee that triggering occurs at the same point in the burst each sweep. Figure 3-6 shows marker
measurements for pulses on CH1 and CH2.
