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Re: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for
From: |
Bob McGwier |
Subject: |
Re: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for GMSK? |
Date: |
Fri, 11 Apr 2008 14:09:04 -0400 |
User-agent: |
Thunderbird 2.0.0.12 (Windows/20080213) |
Long, Jeffrey P. wrote:
While we are on the topic of clock recovery and someone more
knowledgeable than me is reading :) I would like to pose a question to
Bob. How might one do clock recovery on a M-ary CPM signal? It sounds
like a ML sequence technique might be an option but is there a simpler
ad-hoc technique that works as well? My "superiors" tell me to just do
clock recovery on a 2-ary modulated preamble and then hold it for the
rest of the packet when it switches to your M-ary mode. I suppose this
would work but I think it might be a little too much work in GNU right
now until the meta data extra channel thing is ready, right? For
simplicity I would prefer a technique that could run on streaming data
like the M&M.
thanks
Jeff
Jeff:
The answer is between the two.
;-)
Use the 2-ary modulated symbols for timing acquisition and also for
initial carrier recovery. Then since you will be close switch to a
tracking mode: Mengali's joint timing and recovery algorithm for CPM
signals
Search for "Joint Timing and Phase Recovery for CPM signals" by Umberto
Mengali, et. al. The joint estimator helps significantly as you can read.
Bob
--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are, by
definition, not smart enough to debug it." - Brian W. Kernighan
- [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?, George Nychis, 2008/04/11
- RE: [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?, Long, Jeffrey P., 2008/04/11
- Re: [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?, George Nychis, 2008/04/11
- RE: [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?, Long, Jeffrey P., 2008/04/11
- Re: [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?, Bob McGwier, 2008/04/11
- RE: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for GMSK?, Long, Jeffrey P., 2008/04/11
- Re: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for GMSK?,
Bob McGwier <=
- RE: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for GMSK?, Long, Jeffrey P., 2008/04/11
- Re: [Discuss-gnuradio] M&M impl, its parameters, and why does itwork for GMSK?, Bob McGwier, 2008/04/11