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[Discuss-gnuradio] Re: BBN 802.11 code: long preamble only?

From: George Nychis
Subject: [Discuss-gnuradio] Re: BBN 802.11 code: long preamble only?
Date: Sun, 29 Nov 2009 23:50:08 -0500

One more poke...


I'm assuming d_shift is supposed to shift the descrambled bytes to try and find synchronization, but it seems like this doesn't happen?

- George

On Sun, Nov 29, 2009 at 11:35 PM, George Nychis <address@hidden> wrote:
I also think that the decoder is improperly looking for synchronization...

According to the 802.11 spec, the long preamble uses an SFD that is 0xF3A0, and the short is 0x05CF (verified by a quick google (http://www.google.com/search?hl=en&safe=off&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&hs=zoI&q=802.11+0xF3A0+0x05cf&aq=f&oq=&aqi=)

The definition of SFD and RSFD seem to be backwards:

For those a little unfamiliar with the preamble, RFSD = reverse SFD, as the 802.11 spec states that the short preamble uses the reverse of the SFD... but these defines seem to be backwards.

Still trying to get the decoder to pickup a short preamble though...

- George

On Sun, Nov 29, 2009 at 9:46 PM, George Nychis <address@hidden> wrote:
Hi all,

For those of you who have worked closely with the BBN 802.11 code, does it only handle a long preamble?  I have not been able to get it to successfully decode any of my packets, which are all using a short preamble.

- George

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