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[Discuss-gnuradio] M&M impl, its parameters, and why does it work for GM
From: |
George Nychis |
Subject: |
[Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK? |
Date: |
Fri, 11 Apr 2008 12:18:05 -0400 |
User-agent: |
Thunderbird 2.0.0.12 (X11/20080227) |
Hi all,
I've attempted to follow the M&M optimization algorithm paper, which GNU
Radio implements, to try and select proper parameters for a O-QPSK / MSK
implementation floating around that a UCLA group wrote:
http://acert.ir.bbn.com/projects/gr-ucla/
I ask because it seems as though the PHY is not recovering from clock
drift properly, which would be the goal of the M&M block. The blue in
this graph is not important, but note the smearing on the right:
http://cyprus.cmcl.cs.cmu.edu/tmp/graphs/zigbee_sample_dump9_unit_circle_19v20.jpg
That smearing is not recovered from properly by M&M and causes loss, as
an example. This causes approximately anywhere from 5-15% frame loss
over _coax_.
So I was pointed to the M&M paper, to try and understand why its
recovery is not working properly, looking to set proper parameters. The
paper is here:
http://ieeexplore.ieee.org/iel1/2220/8932/00392689.pdf
But, if you read the first paragraph, it states that this algorithm is
NOT for MSK, or GMSK for that matter:
"We are assuming a system whose output comprises nom-
inally synchronised data symbols subject to additive white Gaus-
sian noise, where the transmitter and the receiver use Nyquist root
raised-cosine filters."
So, before I go any further... I was hoping someone could shed light on
how this ends up working out for GMSK which does not use an RRC filter.
Then, why would it not work with the MSK implementation? ;) I
understand that GMSK is band-limited by the Gaussian filter, is this the
significant difference?
I suppose the overall question is the implications of using a CPM signal
when the GR clock recovery block was written using an RRC filter.
Thanks!
George
- [Discuss-gnuradio] M&M impl, its parameters, and why does it work for GMSK?,
George Nychis <=
- 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, 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, 2008/04/11