Giga-tronics 58542 - Page 226

58542 VXIbus Universal Power Meter
A-44 Publication 21555, Rev. E, September 2002
A.9.2 Relative or Referenced Measurements Example 2
The following program finds the 1 dB compression of an amplifier/transmitter at a single frequency.
300 ASSIGN @Pwr_mtr to 70101
310 CLEAR @Pwr_mtr
320 WAIT 1
330 !
340 OUTPUT @Pwr_mtr;CALC1:MODE NORMAL
! Can ONLY use REFerence commands in NORMal
Mode!!
350 OUTPUT @Pwr_mtr;CALC1:POW 1 ! Channel 1 configured to measure sensor 1 power
360 OUTPUT @Pwr_mtr;CALC1:UNIT W ! Transmitter output power in Watts.
370 OUTPUT @Pwr_mtr;CALC2:RAT 1,2 ! Transmitter gain stays in default, dBm.
380 OUTPUT @Pwr_mtr;CALC2:UNIT DBM ! Transmitter output power in Watts. Units are channel,
! not sensor, specific
390 !
400 !
410 OUTPUT @Pwr_mtr;TRIG:SOUR IMM ! TRIG:SOUR must be IMM when using READ#?
420 OUTPUT @Pwr_mtr;INIT:CONT OFF ! INITiate:CONTinuous arming must be OFF when using READ#?
430 !
440 OUTPUT @Pwr_mtr;SENS1:AVER:COUN 1! Sets averaging to manual and one sample per measurement
reading.
450 OUTPUT @Pwr_mtr;SENS2:AVER:COUN 4! Sets averaging to manual and 4 samples per measurement
reading.
460 !
470 OUTPUT @Pwr_mtr;SENS1:CORR:FREQ 1.94E9
! Applies Cal Factor for 1.94 GHz, Sensor 1.
480 OUTPUT @Pwr_mtr;SENS2:CORR:FREQ 7.0E7
! Applies Cal Factor for 70 MHz IF input, Sensor 2.
490 !
500 !#################################################
510 !
520 ! System Setup
530 ! Power Splitter attached to source.
540 ! DUT input and sensor 2 on the splitter outputs.
550 ! Sensor 1 at DUT output.
560 ! Check max power rating on sensor 1 and use an appropriate attenuator if necessary.
570 ! Use offset to account for any necessary attenuation when not using Giga-tronics high power sensors.
580 !
590 !#################################################
600 !
610 ! Relative measurement setup using CALC#:REF:COLL.
620 !
630 OUTPUT @Pwr_mtr;CALC2:REF:MAG 0.00 ! Resets REFerence level from value set with
CALC2:REF:COLL
640 OUTPUT @Pwr_mtr;CALC2:REF:STAT ON ! Enables REFerence operation.
650 !
660 Smal_sig_pwr=-30
670 OUTPUT @Source;OPPL;Smal_sig_pwr ! Set power to small signal region of amp, -30 dBm.
680 OUTPUT @Pwr_mtr;CALC2:REF:COLL ! Takes current measurement and adds inverse to further
! measurements
690 !
700 ! STEP POWER FROM SMALL SIGNAL REGION TO ABOVE 1 dB COMPRESSION LEVEL
710 !
720 FOR I=Smal_sig_pwr TO Smal_sig_pwr+40 STEP .05
730 OUTPUT @Source;OPPL;I ! Increments power level into amplifier’s input. Add wait statement
! at 735 if source settles too slow.
740 OUTPUT @Pwr_mtr;READ2? ! Measures Sensor 1 over sensor 2, dB relationship
750 ENTER @Pwr_mtr;Rdg
760 PRINT Rdg
770 !
780 Comp_lvl=-1
790 IF Rdg<Comp_lvl THEN ! Finds 1 dB compression level
800 OUTPUT @Pwr_mtr;READ1? ! Measures Output Power at sensor 1.