I agree with you doug. After reading through the BBN code, that seems like why they did that. DBPSK and DQPSK appear to be backward compatible decoding wise.
I think the reason why you cannot transmit/decode DQPSK packets is that the entire packet is encoded as DQPSK and not part DBPSK and part DQPSK. The decoding algorithm then fails. --Thanks On Tue, May 12, 2009 at 7:37 AM, Doug Geiger <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Colby Boyer wrote: > > Hi all, > > > > So I am not too familiar with the history of how GNU-Radio has evolved > > over the past few years and I am wondering what are the fundamental > > differences between blks and blks2(old revisions vs new revisions)? > > > > A question I am asking is why did the BBN people who wrote the 802.11b > > code make their own DPSK mod/demod and did not use the function blocks > > provided by gnuradio? Were those blocks simply not available at the > time? > > > > Last question. Has the functionality of teh the DB/QPSK modulations in > > the blks2 library been tested? I'm in the process of cleaning up the > > 802.11b code, and if I can relay on gnu-radio libraries, rather than > > custom C++/python code, that would be better. > > > > Thanks, > > Colby > > For the 802.11b code, I think part of the reasoning was that for > providing 1 and 2Mbps service, the block needed to be able to switch > rapidly between DBPSK and DQPSK (and the block would not know until the > preamble was decoded), so they did both in parallel, and simply switched > which output was actually used as needed. If any of the BBN folks are > still on-list they may have more insight. > Doug > > - -- > Doug Geiger > Research Assistant > Communications and Signal Processing Lab > Oklahoma State University > [email protected] > [email protected] > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.11 (Darwin) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iEYEARECAAYFAkoJiZMACgkQPJjTsCiwNz4vIwCfRh5PTFtdr1a/jwb5uWMBnaV5 > O4QAoIaHY2eLFTbx+mN4dC0hG4nVr+uR > =maw4 > -----END PGP SIGNATURE----- >
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