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Re: [Discuss-gnuradio] Problem in framer_sink
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Problem in framer_sink |
Date: |
Mon, 12 Mar 2007 12:14:29 -0700 |
User-agent: |
Mutt/1.5.9i |
On Sun, Mar 11, 2007 at 02:59:58PM -0700, Johnathan Corgan wrote:
> Achilleas Anastasopoulos wrote:
>
> > Regarding protecting the length field, a rate 1/2 linear block code
> > can always be used.
> >
> > The way it is now it is a repetition code which offers little
> > protection.
>
> As-is there is no FEC in in the digital packet code anyway. When we add
> that, we'll likely do it for the complete header and payload at the same
> time.
I don't think so. We need to be able to reliably determine the length
of the packet (which we get from the header), to find the end of the
packet.
I think Achilleas' suggestion of a rate 1/2 block code for the header is
the way to go. Achilleas, do you have a specific suggestion? Golay
would protect 12-bits. Any off-the-shelf code that does a good job on
16-bits of payload?
Also, splitting the PHY layer framing from the handling of the payload
CRC / FEC allows upper layers to be independent of the low-level
framing mechanism.
Eric