Giga-tronics 8650A Series, Operation Manual

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Series 8650A Universal Power Meters
2-32 Manual 31470, Rev. E, April 2001
power measurements is two-fold. First, care should be taken to keep the peak power level applied to the
sensor below the maximum recommended level. Second, when trying to minimize modulation-induced
measurement error for carriers separated by more the specified bandwidth of the sensor, it is the peak
power level that should be kept below about -20 dBm.
2.3.12 Peak Hold
When the Peak Hold feature is selected, the 8650A displays the highest instantaneous power measured
from the time the feature is enabled until it is reset by the user. In other words, the displayed value
tracks the measured value only when the measured value is rising to a new maximum. When the
measured value falls, the displayed value holds at the maximum. When the peak hold feature is reset,
the displayed value falls to the current measured value and the process begins again.
When the Peak Hold feature is selected, the minimum average power level that can be accurately
measured is -20 dBm. Beginning in firmware version 1.51, this has been implemented to increase
accuracy and maintain wide bandwidth of Peak Hold measurement over the peak power range of -20
dBm to +20 dBm. The Peak Hold selection will also affect Histogram measurement if there is power
below -20 dBm. To obtain accurate average power measurements below -20 dBm, remove the display
line containing Peak Hold (or, in remote control, by sending the command which disables the Peak
Hold feature).
The Peak Hold feature is available in the MAP, PAP, and BAP measurement modes; it may be enabled
from the front panel under the Display Data Line Configuration setup menu, or over the GPIB. Peak
Hold is reset by pressing [
Reset Line n ] (or, in remote control, by sending the command which activates
the Peak Hold feature).
The reset function controls the time resolution of the reading (that is, for finer resolution, reset more
frequently).
NOTE:
[Reset Line n] for Peak Hold also resets the Crest Factor.
Figure 2-18: Peak Hold
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Hold
Hold
Hold
Hold
Hold
Peak Hold
(Reset)
(Reset)
Peak
Hold
Instantaneous
Time
P
ower