1 files changed, 97 insertions, 0 deletions
diff --git a/gnuradio-examples/python/apps/hf_radio/ssbdemod.py b/gnuradio-examples/python/apps/hf_radio/ssbdemod.py
new file mode 100644
index 0000000000..c73567b666
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+++ b/gnuradio-examples/python/apps/hf_radio/ssbdemod.py
@@ -0,0 +1,97 @@
+# This tries to push the hilbert transform for ssb demod back into the
+# freq. xlating filter.
+#
+# The usual gnuradio copyright notice is hereby included by reference.
+#
+# The starting point for this was weaver_isb_am1_usrp3.py.
+#
+# The tap coefficients for freq_xlating_fir_filter_ccf were generated
+# externally and are read from a file because I didn't want to learn how
+# to make fir filters with arbitrary phase response using python numeric
+# facilities.
+#
+# They were generated using Scilab which I am already familiar with.
+# M. Revnell Jan 06
+
+from gnuradio import gr, gru
+from gnuradio import audio
+from gnuradio import usrp
+
+class ssb_demod( gr.hier_block ):
+    def __init__( self, fg, if_rate, af_rate ):
+
+        self.if_rate  = if_rate
+        self.af_rate  = af_rate
+        self.if_decim = if_rate / af_rate
+        self.sideband = 1
+
+        self.xlate_taps = ([complex(v) for v in file('ssb_taps').readlines()])
+        
+        self.audio_taps = gr.firdes.low_pass(
+            1.0,
+            self.af_rate,
+            3e3,
+            600,
+            gr.firdes.WIN_HAMMING )
+
+        self.xlate = gr.freq_xlating_fir_filter_ccc(
+            self.if_decim,
+            self.xlate_taps,
+            0,
+            self.if_rate )
+
+        self.split = gr.complex_to_float()
+
+        self.lpf = gr.fir_filter_fff(
+            1, self.audio_taps )
+
+        self.sum   = gr.add_ff( )
+        self.am_sel = gr.multiply_const_ff( 0 )
+        self.sb_sel = gr.multiply_const_ff( 1 )
+        self.mixer  = gr.add_ff()
+        self.am_det = gr.complex_to_mag()
+                
+        fg.connect(   self.xlate,       self.split      )
+        fg.connect( ( self.split,0 ), ( self.sum,0    ) )
+        fg.connect( ( self.split,1 ), ( self.sum,1    ) )
+        fg.connect(    self.sum,        self.sb_sel     )
+        fg.connect(    self.xlate,      self.am_det     )
+        fg.connect(    self.sb_sel,   ( self.mixer, 0 ) )
+        fg.connect(    self.am_det,     self.am_sel     )
+        fg.connect(    self.am_sel,   ( self.mixer, 1 ) )
+        fg.connect(    self.mixer,      self.lpf        )
+        
+        gr.hier_block.__init__( self, fg, self.xlate, self.lpf )
+
+    def upper_sb( self ):
+        self.xlate.set_taps([v.conjugate() for v in self.xlate_taps])    
+        self.sb_sel.set_k( 1.0 )
+        self.am_sel.set_k( 0.0 )
+
+    def lower_sb( self ):
+        self.xlate.set_taps(self.xlate_taps)
+        self.sb_sel.set_k( 1.0 )
+        self.am_sel.set_k( 0.0 )
+        
+    def set_am( self ):
+        taps = gr.firdes.low_pass( 1.0,
+                                   self.if_rate,
+                                   5e3,
+                                   2e3,
+                                   gr.firdes.WIN_HAMMING )
+        self.xlate.set_taps( taps )
+        self.sb_sel.set_k( 0.0 )
+        self.am_sel.set_k( 1.0 )
+
+    def set_bw( self, bw ):
+        self.audio_taps = gr.firdes.low_pass(
+            1.0,
+            self.af_rate,
+            bw,
+            600,
+            gr.firdes.WIN_HAMMING )
+        self.lpf.set_taps( self.audio_taps )
+
+    def tune( self, freq ):
+        self.xlate.set_center_freq( freq )
+