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BPSK strange peaks with spectrum analyzer - RF Cafe Forums
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Post subject: BPSK strange peaks with spectrum analyzer
Posted: Wed Mar 25, 2009 3:40 pm
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Joined: Wed Mar 25, 2009
3:33 pm
Posts: 1 |
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Maybe someone can help me:
I used spectrum
analyzer with very big rbw to view bpsk signal in
peak mode(not RMS).
the data was random
I saw the familiar sinc envalope with nulls
at N*Rb (N-integer) .
what's strange is that
also I saw strange peaks at LO and multiples of
Rb/2.
If I lower the RBW or put detector in
RMS the peaks disappear.
I verified it with
2 different signal generators.
It's wither
a charectaristic of the signal or spectrum analyzer
related phoneomena.
PLEASE HELP ME
confused from Israel....
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Dexter |
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Post subject: Re: BPSK strange peaks with spectrum analyzer
Posted: Sat Apr 11, 2009 11:42 am
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| Captain |
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Joined: Thu May 04, 2006
7:37 am
Posts: 8 |
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Lurker:
Sounds like LO leakage from improper
DC cancellation. You might want to check your DC
levels on I/Q data input to the modulator.
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RDO-RF |
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Post subject: Re: BPSK strange peaks with spectrum analyzer
Posted: Sat Apr 11, 2009 8:14 pm
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| Captain |
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Joined: Wed Apr 08, 2009
7:53 am
Posts: 17 |
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Hello Lurker,
It is normal to have different
measurement results if you read power to a digital
modulated signal with different RBW.
Perhaps
the best way to analyze peaks on a signal is to
trace CCDF curves.
Check if you still have those
peaks near LO when filtering a CW or without any
signal.. If the tones disappear, then perhaps you
have some DC filtering problem.. if they still there,
then is something on the synthesizer design..
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Posted 11/12/2012
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