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Re: [Discuss-gnuradio] bytes_to_syms

From: Rahul Dhar
Subject: Re: [Discuss-gnuradio] bytes_to_syms
Date: Fri, 4 Mar 2005 15:27:42 -0500
User-agent: Mutt/1.5.8i

On Tue, Mar 01, 2005 at 01:39:21PM -0800, Eric Blossom wrote:
> On Tue, Mar 01, 2005 at 12:26:52AM -0500, Rahul Dhar wrote:
> > Is "bytes_to_syms" a symbol exported by gr_bytes_to_syms?  I'm trying to
> > understand the framing mechanism.
> > 
> > Thanks,
> > -Rahul
> gr.bytes_to_syms is the SWIG generated wrapper for gr_bytes_to_syms.
> The interface exported to Python is in gr_bytes_to_syms.i
> As you've probably figured out by now, the gr_simple_framer.cc is very
> simple.  It just sticks a 4 byte Barker code (actually, I think we
> just made up a random number because when we wrote this we were
> sitting in a hotel room) at the beginning, followed by a 1 byte
> sequence number and an unused zero byte.

For some reason, the receiving side does not get exactly what the
transmitting side sends.  I have a text file of size 4096 bytes.  The 
payload size is 1024 bytes, so I expect to see 4 frames.  However, I 
only see three frames being transmitted, and the sequence number 
increments from 1 to 2, then takes on arbitrary values.  The output file
on the Rx side has 3048 bytes that match the Tx side, but then garbage 
for the next 2074 bytes.  I see similar behaviour for everything I send,
whether I send/receive at 50k or 100k (btw, what are rate values are
acceptable.  I get error messages saying the interp has to be [4,512]
and a multiple of 4).

Rahul Dhar
Actually, my goal is to have a sandwich named after me.

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