Boonton 4530 Peak Power Meter User Manual - Manual (Page 150)

Chapter 5 Boonton Electronics
Making Measurements 4530 Series RF Power Meter
5-8
Averaging (Optional setting for Pulse Mode) - Sets the trace averaging for reducing noise on the trace
display, marker measurements, and automatic pulse measurements. The default setting is 4, but setting to 32
or higher can significantly reduce noise for low-level pulse waveforms.
Peak Hold (Optional setting for Modulated and Pulse modes) - Allows setting the peak-hold feature so
instantaneous peaks are held indefinitly or automatically decayed, or the mode may be set so the highest and
lowest averaged readings are held.
5.5.3 Trig/Time Menu Settings. These settings are only needed if you will be operating in Pulse Mode.
Time Span (Required setting for Pulse Mode) - The timespan setting is similar to the timebase setting on an
oscilloscope. Setting the timespan tells the power meter how much of a periodic signal to acquire at a time.
The timespan defines the displayed portion of the waveform in graph mode, and limits the interval over which
measurements may be performed. For pulse signals, it is usually a good starting point to set the timespan to
a little longer than the pulse repetition interval, or to a little longer than the pulse width. Once a stable
waveform is visible on the screen, the timespan and trigger delay setting (see below) may be adjusted to show
exactly the desired portion of the measured signal.
Trigger Delay (Require setting for Pulse Mode) - Setting the trigger delay tells the powermeter how much
measurement time before and after the trigger is needed. Assuming Trigger Position is set to Middle (the
default setting), a trigger delay value of 0 will split the measurement interval evenly between pretrigger and
posttrigger. If the timespan is set to 50 microseconds, the measurement interval will begin 25 microseconds
before the trigger edge, and will end 25 microseconds after the edge. If the trigger delay is then set to -15
microseconds, the measurement will be skewed in the pretrigger direction: it will begin 40 microseconds
before the trigger, and end 10 microseconds after.
HoldOff (Optional setting for Pulse Mode) - Trigger holdoff is used to aid in synchronizing with a periodic
burst waveform when the period is longer than the timespan setting, and multiple valid trigger edges may
exist. Trigger holdoff will disable (hold off) triggering for a preset time interval after every valid trigger, and
then re-arm the trigger after the holdoff time is up. This way, the instrument will trigger at the same point on
the waveform each cycle. For example, when viewing a GSM base station signal, more than one time slot may
be active, and the instrument could be triggered by the rising edge of the RF signal on any of the active
timeslots. Setting the trigger delay to just a bit less than the frame rate of 4.62mS will guarantee that there will
be no false triggers during other active timeslots.
Trigger Source (Required setting for Pulse Mode) - Set the trigger source to “Sensor 1” to trigger from the
measured signal itself, or “Ext” to trigger from an external synchronization pulse. See Chapter 3 for other
options.
Trigger Mode (Optional setting for Pulse Mode) - The default trigger mode is “Peak-to-Peak Auto”, which
works fine for most applications, and will always generate a sweep. If signal edges are present, the powermeter
will detect the signal amplitude and adjust the trigger level automatically. If no triggerable signal is found, the
sweep will be triggered anyway after a short time period. Trigger mode may also be set to “Normal”, which
requires a trigger level be set, and will only generate a sweep if a trigger occurs. “Auto” also uses the preset
trigger level, but will still generate a sweep even if there are no trigger edges.
Trigger Level (Optional setting for Pulse Mode) - The trigger level must only be set if Trigger Mode is not set
to “Peak-to-Peak”. The level should generally be set between 3 and 15dB below the maximum expected signal
level, but sometimes it may be necessary to experiment for best results.