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Re: [Discuss-gnuradio] beginning psk31
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] beginning psk31 |
Date: |
Sat, 2 Apr 2005 12:43:09 -0800 |
User-agent: |
Mutt/1.5.6i |
On Fri, Apr 01, 2005 at 08:00:10PM -0500, Chuck Swiger wrote:
> Gang - Todays effort works, a simple script that will repeatedly send the
> letter 'A' :
>
> http://webpages.charter.net/cswiger/psk_experiment.html
Yeah!
> I'm kind of at a lost at how to leverage 'bytes_to_syms' from a
> single sample to 256 or 1024 samples/symbol. 31.25baud is 8000/256
> or 32000/1024 (that's why it's 31.25 - to match the 8000sps
> typically used).
For a quick solution you might want to try something like what Joshua
Lackey did in the GMSK Tx code
(gnuradio-core/src/python/gnuradio/blksimpl/gmsk.py)
# Make samples per symbol copies
interp_taps = (1,) * sps
self.interp = gr.interp_fir_filter_fff(sps, interp_taps)
> Some other challenges are buffering keyboard input and sending idle
> when no keys have been hit.
Is typical psk31 usage to buffer up a line using readline or its
equivalent, and then send it? If so, you might want to create a
source that did a non-blocking read on the tty, or readline, or gui,
or whatever, and return the data it got or an indication that there's
no data to send. For full 8-bit transparency, you might want to have
the source return a stream of shorts, where values between 0 and 255
are valid chars and 0xFFFF indicate there's no input available. On
the other hand, does psk31 support full 8-bit transport? If not, just
use one of the unused codes.
Eric