Fast Iterative Control - HP 8712ET User Manual Supplement

Automated Measurement Setup and Control

Fast Iterative Control

Fast Iterative Control
You may want to quickly and iteratively change the analyzer's
parameters and monitor their effect on your device under test. This
section describes how to quickly change a parameter, take a sweep, and
query a marker.
For example, when measuring an amplifier, you may wish to quickly
choose the optimal input power to the amplifier which will result in a
maximum output of +10 dBm. To do so, you can first set the analyzer's
source power level, then measure the amplifier's output, and then
change the analyzer's source power in the direction that will cause the
measured signal to approach the desired value. This process can be
repeated until the measured amplifier output is within some specified
range of the target value.
When data at only a single frequency is needed, you can achieve the
fastest possible sweep by selecting a CW frequency and setting the
number of points to the minimum value of 3. A SCPI marker command
can be used to read the trace value.
Using this approach, you can typically achieve 3 to 5 sweeps per second.
Following is a listing of an example program named "FAST_CW" that
can be found on your Example Programs Disk.
100 DIM Freq_str$[20]
110 DIM Msg$[100]
120 !
130 IF POS(SYSTEM$("SYSTEM ID"),"HP 871") THEN
140 ASSIGN @Hp8711 TO 800
150 ELSE
160 ASSIGN @Hp8711 TO 716
170 ABORT 7
180 CLEAR 716
190 END IF
200 !
210 ! PRESET, to ensure known state.
220 OUTPUT @Hp8711;"SYST:PRES;*WAI"
230 CLS
240 !
250 ! Set up the analyzer to measure 3 data points.
260 OUTPUT @Hp8711;"SENS1:SWE:POIN 3;*WAI"
270 !
280 ! Select CW display and sweep
290 OUTPUT @Hp8711;"DISP:ANN:FREQ1:MODE CW"
300 OUTPUT @Hp8711;"SENS1:FREQ:SPAN 0 Hz;*WAI"
310 !
320 ! Take a single sweep, leaving the analyzer
330 ! in trigger hold mode.
5-8 Automating Measurements