[amsat-bb] Data representation in G3RUH modem

["Johann Lochner" <lochner@xxxxxxxxxxxxx>]

Hi folks,

If I'm not mistaken, the PAM waveform in the discrete implementation 
of the G3RUH modem is NRZ-L (level) coded.  In the DSP56002EVM 
version, from Doug Braun's site, NRZ-S (inversion, space) coding is 
used.  However, I've used both versions for demodulating Pacsat 
downlinks.  Am I missing something?

While I'm at it: any suggestions for (or pointers to) clock recovery 
algorithms for multi-level PAM?  Should another scrambler polynomial 
be considered for obtaining zero crossings in multi-level PAM?  Does 
NRZ-I (inversion) coding have advantages over NRZ-L?

Regards,
Johann


+------------------------------------------------+
   JG Lochner  ESL, Universiteit van Stellenbosch
   e-pos:      lochner@ing.sun.ac.za
   webtuiste:  http://esl.ee.sun.ac.za/~lochner
+------------------------------------------------+

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