Giga-tronics 8650A Series, Руководство по эксплуатации

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Series 8650A Universal Power Meters
3-106 Manual 31470, Rev. E, April 2001
3.19.7 Peak Hold
The Peak Hold feature causes the measured value to hold at the highest instantaneous power measured
from the time the feature is enabled until it is reset (the measured value changes only when it is rising to
a new maximum, or when it is reset).
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, the Peak Hold feature
should be disabled.
The Peak Hold feature can only be used in the standard measurement collections modes (not in the fast
modes), and only in a modulated measurement mode (MAP, PAP, or BAP).
Peak Hold is not
recommended for use in combination with the V
PROP
F function.
Enabling the Peak Hold Feature
The Peak Hold feature is enabled or disabled by simple commands consisting of one of two function
codes:
Syntax : [AE or BE] [PH0 or PH1]
Examples : OUTPUT 713;AE PH1 ! Enable the Peak Hold feature for sensor A
OUTPUT 713;BE PH0 ! Disable the Peak Hold feature for sensor B
Description : Like the MN0 and CR0 commands, The PH0 command will disable Crest Factor and Min/
Max measurements. Sending the PH1 command after Peak Hold is enabled will reset it.
Peak Hold will also reset when you send a CR1 command (see Section 3.8).
Reading the Peak Hold Value
The Peak Hold value is read over the bus using a simple command:
Syntax : [AE or BE] PKH
Example : OUTPUT 713;AE PKH ! Send the peak hold value for sensor A
Description : The Peak Hold feature monitors the maximum power as it is measured, but does not
provide any feedback to the controller until a PKH command is received. To monitor for a
limit violation, the Limits feature may be more useful (see Section 3.15).
The Peak Hold feature returns the current held value as displayed on the front panel. A PKH command
does not initiate data collection in same manner as a trigger command, such as TR1. To get a good
reading of the Peak Hold value, the procedure is:
1. Set up the signal being measured, and send PH1 to reset the Peak Hold measurement.
2. Send TR2.
3. Read the TR2 data, or wait for the data ready service request (this allows for settling).
4. Send PKH.
5. Read the Peak Hold value.