6. Format both traces simultaneously:
Press [
Shift
], [
A
], [
Data Format
], [
polar IQ constellation
]
Press [
more format setup
], [
symbol dots
].
Press [
Auto Scale
]
Be careful when selecting a reference filter if the demodulation format uses
distributed filtering. The demodulation format used in this example (32
QAM) uses distributed filtering. Therefore, a root-raised-cosine reference
filter was needed to create the ideal signal (to represent filtering at the
transmitter), whereas a raised-cosine reference filter was needed to
demodulate the ideal signal (to represent the total filtering in the system).
Truncate the analysis time record at the beginning (with trigger delay of
about 5 symbols) and at the end (with a result length about 10 symbols
shorter) to eliminate invalid data caused by discontinuities between the
beginning and end of the waveform. Use this truncated signal as a
stimulus for component or system tests.
This signal-versus-reference check is also a good opportunity to see the
effects of changing the symbol rate or filtering in order to demonstrate the
effects of setup parameters which are incompatible with the incoming
signal.
Creating User-defined Signals (Options AYA and AYH)
11 - 5
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