58542 VXIbus Universal Power Meter
A-14 Publication 21555, Rev. E, September 2002
A.4.3 Reading Power Measurements Example 3
The following program configures the power meter for dual channel operation and uses the MEAS#?
command to return power measurement data in NORMal Mode. Please note that measurement speed
per channel decreases slightly in NORMal mode when two channels, versus only a single channel, are
connected and calibrated. In NORMal Mode, single channel measurement rates are slightly faster than
two channel measurement rates. If using CW power sensors, also please note that power measurements
are not performed at specifically the exact, simultaneous instant in time. In NORMal Mode there will
be a short time delay of about 3 ms between the two channels’ sample points, about two and a half orders
of magnitude faster than traditional CW power meters. In BURSt and SWIFT mode this time is about 1
ms. If the user needs to guarantee that power sampling occurs on both channels within a smaller interval
of time, this can be accomplished to within about 2% of the Sample Delay time plus 2 ns using the
Series 80350A Peak Power Sensors and triggering both sensors at the same time. The example below
operates with either Peak or CW power sensors.
260 ASSIGN @Pwr_mtr to 70101
270 CLEAR @Pwr_mtr
280 WAIT 1
290 OUTPUT @Pwr_mtr;CALC1:MODE NORM ! Can ONLY send Configuration Commands in Normal Mode!!
300 OUTPUT @Pwr_mtr;CALC1:POW 1 ! Channel 1 configured to measure sensor 1 power
310 OUTPUT @Pwr_mtr;CALC1:UNIT W ! Transmitter output power in Watts.
320 OUTPUT @Pwr_mtr;CALC2:RAT 1,2 ! Transmitter gain stays in default, dBm.
330 !
340 OUTPUT @Pwr_mtr;SENS1:CORR:FREQ 1.44E9
! Applies Cal Factor for 1.44 GHz to sensor 1 data.
350 OUTPUT @Pwr_mtr;SENS2:CORR:FREQ 0.96E9
! Applies Cal Factor for 960 MHz to sensor 2 data.
360 !
370 FOR I=1 TO 10
380 OUTPUT @Pwr_mtr;MEAS1?;MEAS2? ! Measures Power at sensors.
390 ENTER @Pwr_mtr;Chn_pow 1
400 ENTER @Pwr_mtr;Chn_1rat2
410 PRINT Chn_pow1,Chn_1rat2
420 NEXT I
430 !
550 END
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