Getting Started — 2756P Programmers
See Section 10 in this manual for help in plotting the
waveform.
Getting Smarter
Signal analysis can be even easier. Put the spectrum
analyzer to work to find and measure signals with its
internal waveform-processing capabilities. The full set of
waveform processing commands is described in Section
8 of this manual, and more instructions for their use are
found in Sections 5 and 10 of this manual. To get started
"getting smarter", here is a simple application.
The following 4041 program catalogs the first 10 har-
monics of the CAL OUT signal. Connect a 100 MHz cali-
brator before running this program. If the instrument is
set to other than the power-up state, precede the pro-
gram with the INIT command. As in the other programs
in this manual, Z is the variable that holds the value of
the spectrum analyzer GPIB address.
80 Z-1 ! ADDRESS OF SPECTRUM ANALYZER
90 Print #z:"INIT"
100! CATALOG ROUTINE
110 Print #z:"SPAN 1 MHZ;REFLVL -20
DBM;VIDFLT NARROW;SIGSWP"
120 For
i—1
to 10
130 Print #z:"FREQ
",i*1
.OE+S^SIGSWPiWAIT"
140 Print #z:"FIBIG;TOPSIG;FREQ?;REFLVL?"
150 Input #z:r$
160 Print "SIGNAL ",i,r$
170 Print #z:"REFLVL-20 DBM"
180 Next i
Line 110 — Sets span/div and reference level for the
start of the signal search, and selects narrow video filter
to smooth the data for the routine. The single-sweep
mode is selected so new data can be acquired on com-
mand.
Line 120 — Starts the loop.
Line 130 — Tunes to a harmonic of the calibrator
signal, then starts a sweep to acquire new data. The
WAIT guarantees digital storage is filled with updated
data before proceeding.
Line 140 — FIBIG finds the calibrator harmonic (it
should be the only signal on screen). TOPSIG automati-
cally changes analyzer gain or input attenuation to bring
the signal peak to the reference level (top of screen).
These and other waveform processing commands allow
you to analyze signals without reading in all the display
data and operating on it in your controller.
Line 150 — Inputs the analyzer response.
Line 160 — Because the response to each query in
line 140 begins with a mnemonic for the function, the
analyzer output string acquired in line 150 is intelligible
as is and the frequency and reference level readings are
printed at the controller.
Line 170 — Readies the spectrum analyzer to do it
again.
Line 180 — Goes around again.
The waveform processing commands and query
allow you to analyze data without reading waveforms and
manipulating them in your controller. More details can be
found in Section 8 of this manual, and instructions for
putting spectrum analyzer waveform processing to work
are given in Section 10 of this manual.
Getting Smarter Another Way
The following 4041 program will measure the ampli-
tude and frequency of the 100 MHZ CAL OUT and the
next 9 harmonics of the CAL OUT signal.
80 Z-1 ! ADDRESS OF SPECTRUM ANALYZER
500 Dim m(20)
510 Open #z:"gpib(pri-1,eom-<0>,tim-100):"
520 Print #z:"init;time auto;min 0;span 1m;ref -20"
530 Print #z:"rlm mnoise;vid nar;step 100m;sig"
540 Print #z:"pstep;sig;wai;mfbig;mlocat?;rep 9"
550 Input deln "" #z:m
560 Print m
Lines 500 and 510 — Dimensions array m and sets
the primary address and 4041 data transfer timeout to
100 sec.
Line 520 — Initializes the spectrum analyzer and
sets the time/division, minimum attenuation, frequency
span, and reference level.
Line 530 — Sets the reference level mode and video
filter, establishes a step size of 100 MHz, and enters the
single sweep mode.
Line 540 — Increases the primary marker frequency
by the step value (100MHZ), starts a sweep, waits until
the end of sweep, finds the largest on-screen signal, and
requests the marker frequency and marker amplitude,
and then repeats the sequence 9 more times.
Line 550 — Inputs all 10 marker frequencies and
marker amplitudes.
Line 560 — Prints all 10 marker frequencies and
marker amplitudes.
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