diff options
Diffstat (limited to 'gr-atsc/src')
| -rw-r--r-- | gr-atsc/src/python/README | 8 | ||||
| -rwxr-xr-x | gr-atsc/src/python/interp_short.py | 85 |
2 files changed, 90 insertions, 3 deletions
diff --git a/gr-atsc/src/python/README b/gr-atsc/src/python/README index fb9ec71e3..abe0937b5 100644 --- a/gr-atsc/src/python/README +++ b/gr-atsc/src/python/README @@ -7,10 +7,12 @@ station frequency from the fcc video database, and decimation of 10. 2) Capture data - adjust gain (-g) frequency (-f) and which side the tvrx is on to fit your local setup: -usrp_rx_cfile.py -R B -d 10 -g 65 -f 503e6 atsc_data_6-4m_complex +usrp_rx_cfile.py -s -R B -d 10 -g 65 -f 503e6 atsc_data_6-4m_complex You probably still need fast disks to take the data, like a raid-0 set of -striped sata drives. Make sure there are no or very few Ou overruns. +striped sata drives. Make sure there are no or very few Ou overruns. Saving +the raw usrp data in 'short' form halves the disk space/bus bandwidth that +the usual complex form uses. 3) Make pipes: @@ -22,7 +24,7 @@ mkfifo /tmp/atsc_pipe_5 4) In seperate windows run processes: -./interp.py <input rf data at 6.4Msps> +./interp_short.py <input rf data at 6.4Msps> ./xlate.py ./fpll.py ./btl-fsd.py diff --git a/gr-atsc/src/python/interp_short.py b/gr-atsc/src/python/interp_short.py new file mode 100755 index 000000000..8a022057e --- /dev/null +++ b/gr-atsc/src/python/interp_short.py @@ -0,0 +1,85 @@ +#!/usr/bin/env /usr/bin/python +# +# Copyright 2004 Free Software Foundation, Inc. +# +# This file is part of GNU Radio +# +# GNU Radio is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2, or (at your option) +# any later version. +# +# GNU Radio is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with GNU Radio; see the file COPYING. If not, write to +# the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +# Boston, MA 02111-1307, USA. +# +# This module starts the atsc processing chain taking the captured +# off-air signal created with: +# +# usrp_rx_cfile.py -R <side with tuner, a or b> +# -d 10 set decimation to get signal at 6.4e6 rate +# -f <center of tv signal channel freq> +# -g <appropriate gain for best signal / noise> +# -s output shorts +@ +# All this module does is multiply the sample rate by 3, from 6.4e6 to +# 19.2e6 complex samples / sec, then lowpass filter with a cutoff of 3.2MHz +# and a transition band width of .5MHz. Center of the tv channels is +# then at 0 with edges at -3.2MHz and 3.2MHz. + +from gnuradio import gr +import sys + +def graph (args): + + nargs = len (args) + if nargs == 1: + infile = args[0] + else: + sys.stderr.write('usage: interp.py input_file\n') + sys.exit (1) + + sampling_freq = 6400000 + + fg = gr.flow_graph () + + srcf = gr.file_source (gr.sizeof_short,infile) + s2ss = gr.stream_to_streams(gr.sizeof_short,2) + s2f1 = gr.short_to_float() + s2f2 = gr.short_to_float() + src0 = gr.float_to_complex() + + src1 = gr.sig_source_c (sampling_freq, gr.GR_CONST_WAVE, 1, 0) + src2 = gr.sig_source_c (sampling_freq, gr.GR_CONST_WAVE, 1, 0) + + interlv = gr.interleave(gr.sizeof_gr_complex) + + lp_coeffs = gr.firdes.low_pass ( 3, 19.2e6, 3.2e6, .5e6, gr.firdes.WIN_HAMMING ) + lp = gr.fir_filter_ccf ( 1, lp_coeffs ) + + file = gr.file_sink(gr.sizeof_gr_complex,"/tmp/atsc_pipe_1") + + fg.connect( srcf, s2ss ) + fg.connect( (s2ss, 0), s2f1) + fg.connect( (s2ss, 1), s2f2) + fg.connect( s2f1, (src0,0) ) + fg.connect( s2f2, (src0,1) ) + fg.connect( src0, (interlv, 0) ) + fg.connect( src1, (interlv, 1) ) + fg.connect( src2, (interlv, 2) ) + fg.connect( interlv, lp, file ) + + fg.start() + raw_input ('Head End: Press Enter to stop') + fg.stop() + +if __name__ == '__main__': + graph (sys.argv[1:]) + + |