To Demodulate And Analyze An Msk Signal - Agilent Technologies 89410A Operator's Manual

Using Digital Demodulation (Opt. AYA)

To demodulate and analyze an MSK signal

This example uses an MSK signal from the Signals Disk to show you how
to demodulate an MSK signal and view MSK phase transitions.
1.
Load "MSK.DAT" from the Signals Disk into the arbitrary source:
Perform steps 1, 2, and 3 in ''To prepare a digital demodulation
measurement.'' For step 2, load the "MSK.DAT" signal from the Signals
Disk instead of ''PI4DQPSK.DAT.''
2.
Select appropriate setup parameters:
Press [ ] and select the optimum range.
Range
Press [ ], [
Frequency center
Press [ ], 1, [
span MHz
Press [ ], [
Trigger trigger type
If you don't know how to select the optimum range, see ''To prepare a
digital demodulation measurement.''
3.
Demodulate the signal:
Press [
Instrument Mode
[ ], [
Instrument Mode demod type
When you turn on digital demodulation, you may see this message:
Maximum span limited by symbol rate and maximum span/symbol rate ratio
This message informs you that the frequency span is limited by the
currently selected symbol rate. In other words, the symbol rate used in
the last digital demodulation measurement is too small. The next step
automatically selects the correct symbol rate and restores the frequency
span to 1 MHz, so you can ignore this message. For additional details
about symbol rate and frequency span interactions, see ''Parameter
Interactions'' in the Digital Demodulation Concepts chapter.
4.
Configure the digital demodulator for a GSM measurement:
Press
[demodulation setup
Press [ ], [
Time pulse off
5.
Format traces A and C to view unwrapped phase versus group delay:
Press [ ]
A
Press [ ], [
Data Format
], [
Press [
Display view/overlay traces
Press [ ], [
C Measurement Data
Press [ ], [ ], [
Shift A
Press [ ]
Auto Scale
8 - 14
], 5, [ ]
MHz
].
], [ ], [
internal source return
], [ ] (with option AYH, press
Digital Demodulation
], [ ], [
Digital Demodulation
], [ ], [
demod format standard setups
], [
]
sync off
]
phase unwrap
], [ ]
C on
], [
IQ measured time
], [
more format setup symbols dots
], [ ], 74, [ ].
ch1 delay us
Return]).
], [ ]
GSM
], [ ], [
Data Format group delay
]
.
]