Houston, we have a trunk.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3122 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 89 insertions, 0 deletions

diff --git a/gnuradio-examples/python/audio/dial_squelch.py b/gnuradio-examples/python/audio/dial_squelch.py
new file mode 100755
index 000000000..d947e5860
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+++ b/gnuradio-examples/python/audio/dial_squelch.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+
+# Copyright 2006 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.
+# 
+
+from gnuradio import gr, audio, eng_option
+from gnuradio.eng_option import eng_option
+from math import pi, cos
+from optparse import OptionParser
+
+"""
+This script generates a standard dial tone and then applies a sinusoidal
+envelope to vary it's loudness.  The audio is then passed through the
+power squelch block before it gets sent to the sound card. By varying
+the command line parameters, one can see the effect of differing
+amounts of power averaging, threshold, and attack/decay ramping.
+"""
+
+class app_flow_graph(gr.flow_graph):
+    def __init__(self, options, args):
+        gr.flow_graph.__init__(self)
+	
+	# Create dial tone by adding two sine waves
+	SRC1 = gr.sig_source_f(options.rate, gr.GR_SIN_WAVE, 350, 0.5, 0.0)
+	SRC2 = gr.sig_source_f(options.rate, gr.GR_SIN_WAVE, 440, 0.5, 0.0)
+	ADD = gr.add_ff()
+
+	# Convert to vector stream (and back) to apply raised cosine envelope
+	# You could also do this with a vector_source_f block that repeats.
+	S2V = gr.stream_to_vector(gr.sizeof_float, options.rate)
+	ENV = [0.5-cos(2*pi*x/options.rate)/2 for x in range(options.rate)]
+	MLT = gr.multiply_const_vff(ENV)
+	V2S = gr.vector_to_stream(gr.sizeof_float, options.rate)
+
+	# Run through power squelch with user supplied or default options
+	# Zero output when squelch is invoked
+	SQL = gr.pwr_squelch_ff(options.threshold, options.alpha, options.ramp, False)
+	DST = audio.sink(options.rate)
+
+	# Solder it all together
+	self.connect(SRC1, (ADD, 0))
+	self.connect(SRC2, (ADD, 1))
+	self.connect(ADD, S2V, MLT, V2S, SQL, DST)
+	
+def main():
+    parser = OptionParser(option_class=eng_option)
+    parser.add_option("-r", "--rate", type="int", default=8000, help="set audio output sample rate to RATE", metavar="RATE")
+    parser.add_option("-t", "--threshold", type="eng_float", default=-10.0, help="set power squelch to DB", metavar="DB")
+    parser.add_option("-a", "--alpha", type="eng_float", default=None, help="set alpha to ALPHA", metavar="ALPHA")
+    parser.add_option("-m", "--ramp", type="int", default=None, help="set attack/decay ramp to SAMPLES", metavar="SAMPLES")
+    (options, args) = parser.parse_args()
+
+    if options.alpha == None:
+	options.alpha = 50.0/options.rate
+	
+    if options.ramp == None:
+	options.ramp = options.rate/50	# ~ 20 ms
+
+    print "Using audio rate of", options.rate
+    print "Using threshold of", options.threshold, "db"
+    print "Using alpha of", options.alpha
+    print "Using ramp of", options.ramp, "samples"
+
+    fg = app_flow_graph(options, args)
+
+    try:
+      fg.run()
+    except KeyboardInterrupt:
+      pass
+
+if __name__ == "__main__":
+    main()