Agilent Technologies E7405A User Manual
Chapter 1
67
Making Basic Measurements
Demodulating FM Signals
Figure 1-57
Determining the Offset
Demodulate the FM Signal
1.
Connect an antenna to the analyzer INPUT.
2.
Perform a factory preset by pressing
Preset
,
Factory Preset
(if
present).
3.
Tune the analyzer to a peak the peak of one of your local FM
broadcast signals, for example 97.7 MHz by pressing
broadcast signals, for example 97.7 MHz by pressing
FREQUENCY
,
Center Freq
, 97.7,
MHz
.
4.
Set the span to 1 MHz by pressing
SPAN
,
Span
, 1,
MHz
.
5.
Press
AMPLITUDE
,
Ref Level
, and use the front-panel knob to bring
the signal peak to the reference level.
6.
Press
Scale Type
(Lin) to place the analyzer in linear scale mode.
7.
Tune above or below the FM signal by the offset noted above in
, in this example 151 kHz. Press
FREQUENCY
,
CF Step,
151,
kHz
, then press
Center Freq
and use the step-up key (
↑
) or step-down
key (
↓
).
8.
Set the resolution bandwidth to 100 kHz, by pressing
BW/Avg
,
Res
BW
, 100,
kHz
.
9.
Set the span to zero by pressing
SPAN
,
Zero Span
.
10.
Turn off the automatic alignment by pressing
System
,
Alignments
,
Auto Align
,
Off
.
11.
Listen to the demodulated signal through the speaker by pressing
Det/Demod
,
Demod
,
AM
,
Speaker
(On), then adjust the volume using
the front-panel volume knob.