1 files changed, 78 insertions, 0 deletions
diff --git a/gr-analog/python/analog/standard_squelch.py b/gr-analog/python/analog/standard_squelch.py
new file mode 100644
index 0000000000..3ed9ebceaa
--- /dev/null
+++ b/gr-analog/python/analog/standard_squelch.py
@@ -0,0 +1,78 @@
+#
+# Copyright 2005,2007,2012 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 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
+from gnuradio import blocks
+from gnuradio import filter
+
+class standard_squelch(gr.hier_block2):
+    def __init__(self, audio_rate):
+	gr.hier_block2.__init__(self, "standard_squelch",
+				gr.io_signature(1, 1, gr.sizeof_float), # Input signature
+				gr.io_signature(1, 1, gr.sizeof_float)) # Output signature
+
+        self.input_node = blocks.add_const_ff(0)          # FIXME kludge
+
+        self.low_iir = filter.iir_filter_ffd((0.0193,0,-0.0193),(1,1.9524,-0.9615))
+        self.low_square = blocks.multiply_ff()
+        self.low_smooth = filter.single_pole_iir_filter_ff(1/(0.01*audio_rate))   # 100ms time constant
+
+        self.hi_iir = filter.iir_filter_ffd((0.0193,0,-0.0193),(1,1.3597,-0.9615))
+        self.hi_square = blocks.multiply_ff()
+        self.hi_smooth = filter.single_pole_iir_filter_ff(1/(0.01*audio_rate))
+
+        self.sub = blocks.sub_ff();
+        self.add = blocks.add_ff();
+        self.gate = blocks.threshold_ff(0.3,0.43,0)
+        self.squelch_lpf = filter.single_pole_iir_filter_ff(1/(0.01*audio_rate))
+
+        self.div = blocks.divide_ff()
+        self.squelch_mult = blocks.multiply_ff()
+
+	self.connect(self, self.input_node)
+        self.connect(self.input_node, (self.squelch_mult, 0))
+
+        self.connect(self.input_node,self.low_iir)
+        self.connect(self.low_iir,(self.low_square,0))
+        self.connect(self.low_iir,(self.low_square,1))
+        self.connect(self.low_square,self.low_smooth,(self.sub,0))
+        self.connect(self.low_smooth, (self.add,0))
+
+        self.connect(self.input_node,self.hi_iir)
+        self.connect(self.hi_iir,(self.hi_square,0))
+        self.connect(self.hi_iir,(self.hi_square,1))
+        self.connect(self.hi_square,self.hi_smooth,(self.sub,1))
+        self.connect(self.hi_smooth, (self.add,1))
+
+        self.connect(self.sub, (self.div, 0))
+        self.connect(self.add, (self.div, 1))
+        self.connect(self.div, self.gate, self.squelch_lpf, (self.squelch_mult,1))
+	self.connect(self.squelch_mult, self)
+
+    def set_threshold(self, threshold):
+        self.gate.set_hi(threshold)
+
+    def threshold(self):
+        return self.gate.hi()
+
+    def squelch_range(self):
+        return (0.0, 1.0, 1.0/100)