To perform FM demodulation
The following procedure demonstrates FM demodulation using a file on the
signals disk that you load into the analyzer’s data registers and use as an
arbitrary source signal. The sample signal is a 5 MHz carrier that is phase
modulated with a triangle wave.
1. Initialize the analyzer:
Press [
Instrument Mode
], [
receiver
], then press:
89410A: [
input section (0-10 MHz)
].
89441A: [
RF section (0-10 MHz)
].
Press [
Preset
].
2. Load the source signal file PMSIG.DAT into data register D2:
Insert the Signals Disk in the analyzer’s disk drive.
Press [
Save/Recall
], [
default disk
], [
internal disk
] to select the internal disk drive.
Press [
Return
] (bottom softkey), [
catalog on
]to display the files on the disk.
Rotate the knob until the file PMSIG.DAT is highlighted.
Press [
recall trace
], [
from file into D2
], [
enter
].
3. Connect the SOURCE output to the channel 1 INPUT.
4. Turn on the source and select arbitrary signal D2
(a 25 kHz triangle wave modulating a 5 MHz carrier):
Press [
Source
], [
source on
], [
source type
], [
arb data reg
], [
D2
], [
Return
], [
arbitrary
].
5. Set the frequency span:
6. Press [
Frequency
], [
span
], 500, [
kHz
].
The display should now appear as shown below.
Spectrum of the phase modulated signal.
7. Select FM demodulation:
Demodulating an Analog Signal
1-6
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