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PCTAM
Percent AM
Turns on or off the percent AM measurement.
Syntax
Equivalent
Softkey:
$!
AM
ON OFF.
Related Commands: MKPX, PCTAMR, TH.
Example
OUTPUT
718;"MOV
PCTAM,l;"
OUTPUT
718;"PCTAMR?;"
Turns on the percent AM
rneasurmt.
Queries
PCTAMR.
FCTAMR
contains the results
of
the
percent AMmeasurement.
ENTER
718;Percent
Stores
the value
of
PCTMR
in the variable
Brcent.
PRINT "Percent AM is
",Percent
Prints the results.
OUTPUT
718;"MOV
PCTAM,O;"
Turns
ofl
the percent AM measurement.
Description
Setting PCTAM to 0 turns off the percent AM function. Setting PCTAM to 1 turns on the
percent AM function. When the percent AM function is turned on, the spectrum analyzer finds
the signal with the highest amplitude, and then finds two signals (with lower amplitudes) on
either side of the highest signal. The highest on-screen signal is assumed to be the carrier, and
the adjacent signals are assumed to be the sidebands. The amplitude levels of all three signals
are measured, and the percent AM is calculated using the carrier level and the sideband with
the higher amplitude level. Percent AM is calculated as follows:
Percent Ah4 = 200 x
Leuek7a,rier
LeV47ideband
The percent AM measurement is repeated at the end of every sweep (PCTAM uses the ONEOS
command) until you turn off the percent AM measurement. You must query PCTAMR to
determine the percent AM.
PCTAM can perform the percent AM measurement only if there are three on-screen signals
that have the characteristics of a carrier with two sidebands. Also, to be considered a signal,
the levels of the carrier and sideband signals must be greater than the peak excursion above
the threshold. If there are not three signals that fit the characteristics of a carrier with two
sidebands, the value of PCTAMR will be -100.
You can execute the PCTAM command two different ways. You can either execute the PCTAM
command directly (for example,
"PCTAM 1;
‘I)
or use the MOV command to move the 1 or 0 into
5-416
Programming Commands