add audio_p25_tx.py

git-svn-id: http://op25.osmocom.org/svn/trunk@168 65a5c917-d112-43f1-993d-58c26a4786be

python/audio_p25_tx.py

@@ -0,0 +1,105 @@
+#!/usr/bin/env python
+#
+# accepts input file of P25 symbols consisting of packed characters
+# soundcard output signal is suitable for direct connection to an FM transmitter
+#
+# Copyright 2005,2006,2007 Free Software Foundation, Inc.
+#
+# audio_p25_tx.py original portions (C) Copyright 2009, KA1RBI
+# coeffs for shaping and cosine filter from Eric Ramsey thesis 
+# 
+# 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 3, 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., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+# 
+
+import math
+from gnuradio import gr, gru, audio, eng_notation, optfir
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+class app_top_block(gr.top_block):
+    def __init__(self, options, queue):
+        gr.top_block.__init__(self, "mhp")
+
+        sample_rate = options.sample_rate
+
+        arity = 2
+        IN = gr.file_source(gr.sizeof_char, options.input_file, options.repeat)
+        B2C = gr.packed_to_unpacked_bb(arity, gr.GR_MSB_FIRST)
+        mod_map = [1.0, 3.0, -1.0, -3.0]
+        C2S = gr.chunks_to_symbols_bf(mod_map)
+        if options.reverse:
+            polarity = gr.multiply_const_ff(-1)
+        else:
+            polarity = gr.multiply_const_ff( 1)
+
+        symbol_rate = 4800
+        samples_per_symbol = sample_rate // symbol_rate
+        excess_bw = 0.1
+        ntaps = 11 * samples_per_symbol
+        rrc_taps = gr.firdes.root_raised_cosine(
+            samples_per_symbol, # gain  (sps since we're interpolating by sps
+            samples_per_symbol, # sampling rate
+            1.0,                # symbol rate
+            excess_bw,          # excess bandwidth (roll-off factor)
+            ntaps)
+        rrc_filter = gr.interp_fir_filter_fff(samples_per_symbol, rrc_taps)
+
+        rrc_coeffs = [0, -0.003, -0.006, -0.009, -0.012, -0.014, -0.014, -0.013, -0.01, -0.006, 0, 0.007, 0.014, 0.02, 0.026, 0.029, 0.029, 0.027, 0.021, 0.012, 0, -0.013, -0.027, -0.039, -0.049, -0.054, -0.055, -0.049, -0.038, -0.021, 0, 0.024, 0.048, 0.071, 0.088, 0.098, 0.099, 0.09, 0.07, 0.039, 0, -0.045, -0.091, -0.134, -0.17, -0.193, -0.199, -0.184, -0.147, -0.085, 0, 0.105, 0.227, 0.36, 0.496, 0.629, 0.751, 0.854, 0.933, 0.983, 1, 0.983, 0.933, 0.854, 0.751, 0.629, 0.496, 0.36, 0.227, 0.105, 0, -0.085, -0.147, -0.184, -0.199, -0.193, -0.17, -0.134, -0.091, -0.045, 0, 0.039, 0.07, 0.09, 0.099, 0.098, 0.088, 0.071, 0.048, 0.024, 0, -0.021, -0.038, -0.049, -0.055, -0.054, -0.049, -0.039, -0.027, -0.013, 0, 0.012, 0.021, 0.027, 0.029, 0.029, 0.026, 0.02, 0.014, 0.007, 0, -0.006, -0.01, -0.013, -0.014, -0.014, -0.012, -0.009, -0.006, -0.003, 0]
+
+        # rrc_coeffs work slightly differently: each input sample
+        # (from mod_map above) at 4800 rate, then 9 zeros are inserted
+        # to bring to a 48000 rate, then this filter is applied:
+        # rrc_filter = gr.fir_filter_fff(1, rrc_coeffs)
+        # FIXME: how to insert the 9 zero samples using gr ?
+
+        # FM pre-emphasis filter
+        shaping_coeffs = [-0.018, 0.0347, 0.0164, -0.0064, -0.0344, -0.0522, -0.0398, 0.0099, 0.0798, 0.1311, 0.121, 0.0322, -0.113, -0.2499, -0.3007, -0.2137, -0.0043, 0.2825, 0.514, 0.604, 0.514, 0.2825, -0.0043, -0.2137, -0.3007, -0.2499, -0.113, 0.0322, 0.121, 0.1311, 0.0798, 0.0099, -0.0398, -0.0522, -0.0344, -0.0064, 0.0164, 0.0347, -0.018]
+        shaping_filter = gr.fir_filter_fff(1, shaping_coeffs)
+
+        OUT = audio.sink(sample_rate, options.audio_output)
+        amp = gr.multiply_const_ff(options.factor)
+
+        self.connect(IN, B2C, C2S, polarity, rrc_filter, shaping_filter, amp)
+        # output to both L and R channels
+        self.connect(amp, (OUT,0) )
+        self.connect(amp, (OUT,1) )
+
+def main():
+    parser = OptionParser(option_class=eng_option)
+    parser.add_option("-f", "--factor", type="eng_float", default=1.0, help="multiply factor")
+    parser.add_option("-i", "--input-file", type="string", default="in.dat", help="specify the input file")
+    parser.add_option("-r", "--repeat", action="store_true", default=False, help="repeat input in a loop")
+    parser.add_option("-v", "--reverse", action="store_true", default=False, help="reverse polarity")
+    parser.add_option("-s", "--sample-rate", type="int", default=48000)
+    parser.add_option("-O", "--audio-output", type="string", default="", help="pcm input device name.  E.g., hw:0,0 or /dev/dsp")
+    (options, args) = parser.parse_args()
+
+ 
+    queue = gr.msg_queue()
+    tb = app_top_block(options, queue)
+    try:
+        tb.start()
+        while 1:
+            if not queue.empty_p():
+                sys.stderr.write("main: q.delete_head()\n")
+                msg = queue.delete_head()
+    except KeyboardInterrupt:
+        tb.stop()
+
+if __name__ == "__main__":
+    main()