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198 Chapter 1
GPIB Command Dictionary
DECoder subsystem
:POLarity <string>
:POLarity?
These commands match/query the polarity of the encoded signal being
analyzed. This function is helpful for restoring the proper data polarity
when the transmitter, repeater, or receiver in you communications
system has an odd number of inversions. These inversions cause the
received data to be inverted when decoded.
• When DEC:POL ‘Norm’ is used, a logical high (1) is displayed when a
positive peak in the received signal is detected. A negative peak
displays a logical low (0).
• When DEC:POL ‘Invert’ is used, a logical low (0) is displayed when a
positive peak in the received signal is detected. A negative peak
displays a logical high (1).
Inverting amplifiers used in transmitters, receivers, and repeaters can
cause an inversion of the modulating digital data. If the decoded signal
does not display the expected results, change the polarity to see if the
signal is being inverted before it is decoded.
Syntax
DEC:POL ‘Norm’
‘Invert’
DEC:POL?
Screen/field equivalent
DEC:POL controls the Polarity field on the SIGNALING DECODER
screen when the Mode field is set to AMPS-TACS or NAMP-NTAC.
:STOP
This command is used to disarm the decoder when you are making
single measurements (DEC:ARM:MODE ‘Single’). It is not used with
continuous measurements.
Syntax
DEC:STOP
Screen/field equivalent
DEC:STOP controls the Stop Meas field on the SIGNALING
DECODER screens.