At 02:13 PM 3/31/2005 -0800, you wrote:
I am especially interested in using gnuradio for PSK31.
It turns out making a psk31 idle is really simple:
samp_freq = 48000
pskmod = 31.25 /2
bpsk = gr.sig_source_f(samp_freq,gr.GR_COS_WAVE,pskmod,1,0) tone = gr.sig_source_f(samp_freq, gr.GR_SIN_WAVE,1e3,1,0)
mixer = gr.multiply_ff()dst = audio.sink(samp_freq)
self.connect(bpsk,(mixer, 0))
self.connect(tone,(mixer, 1))
self.connect(mixer,dst)here's the above signal: http://webpages.charter.net/cswiger/gnuradio_psk31.jpg
and audio from a 'real' gpsk31: http://webpages.charter.net/cswiger/gpsk31_audio.jpg
Not sure if Ilia's block will work for that as we need 'many cycles / bit' instead of one
and also pulse shaping. Maybe something like [data source at 31 baud] -> [bytes to syms] ->
[interpolation to IF rate with root raised cosine filter] -> [IF mixer] -> [usrp].
Anyway, it look real doable, as an elegant solution using the usrp to directly translate and
interpolate a signal into the RF domain and do away with the costly rube-goldberg audio ssb modulation
mess.
--Chuck
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