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Modifying the Program
Remote operation of the spectrum analyzer is similar to manual operation. Remote
measurements are executed by commands that correspond to front-panel keys and softkeys.
The first chapter in the spectrum analyzer operating manual shows you how to make a simple
measurement using the calibration signal. We can add instructions to our program so that it
will make the same measurement. (Because the manual process closely resembles that of
the program, you may want to review the chapter entitled “Making a Measurement” in the
HP 8590 E-Series and L.-S&es Spectrum Analyzers User’s Guide.)
By inserting a few lines into the initial program, we can set functions such as the center
frequency and span, and we can activate a marker to find a signal’s frequency and amplitude.
Program Example for the HP-IB Interface
First, we set the center frequency to 300 MHz. The CF command corresponds to the center
frequency function,
CEnTER
FREQ . (All spectrum analyzer commands, such as CF, are
described in Chapter 5.)
Insert the following program line between lines 40 and 50:
41 OUTPUT
Analyzer;"CF
300MZ;"
Next, we set the span to 200 MHz with the SP command. Add the following program line:
42 OUTPUT.
Analyzer;"SP
200MZ;"
Because we are controlling the sweep, we must update the spectrum analyzer display screen
with the following program line:
43 OUTPUT
Ana1yzer;"T.S;"
When the program is executed, the spectrum analyzer takes one full sweep before executing
line 41. Line 41 changes the center frequency to 300 MHz, and line 42 changes the span to
200
MHz.
Enter the following program line to place a marker at the highest peak on the trace with a
MKPK HI command:
44 OUTPUT
Analyzer:"MKPK
HI;"
The completed program is shown below:
05
!File:
"IBPROG2"
10
Analyzer=718
20
CLEAR Analyzer
30
OUTPUT
Analyzer;"IP;"
40
OUTPUT
Analyzer;"SNGLS;TS;"
41
OUTPUT
Analyzer;"CF
300MZ;”
42
OUTPUT
Analyzer;"SP
200MZ;"
43
OUTPUT
Analyzer;"TS;"
44
OUTPUT
Analyzer;"MKPK
HI;"
50
LOCAL 7
60
END
Run the program to make the measurement. Watch the spectrum analyzer display as it
completes each instruction. Notice that the program executes the instructions faster than is
possible from the front panel.
2-4 Writing a Program