Imported Upstream version 3.2.2

[debian/gnuradio] / gnuradio-core / src / python / gnuradio / blks2impl / wfm_tx.py

diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/wfm_tx.py b/gnuradio-core/src/python/gnuradio/blks2impl/wfm_tx.py
new file mode 100644 (file)
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+++ b/gnuradio-core/src/python/gnuradio/blks2impl/wfm_tx.py
@@ -0,0 +1,79 @@
+#
+# Copyright 2005,2007 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, optfir
+from gnuradio.blks2impl.fm_emph import fm_preemph
+
+class wfm_tx(gr.hier_block2):
+    def __init__(self, audio_rate, quad_rate, tau=75e-6, max_dev=75e3):
+        """
+        Wide Band FM Transmitter.
+
+        Takes a single float input stream of audio samples in the range [-1,+1]
+        and produces a single FM modulated complex baseband output.
+
+        @param audio_rate: sample rate of audio stream, >= 16k
+        @type audio_rate: integer
+        @param quad_rate: sample rate of output stream
+        @type quad_rate: integer
+        @param tau: preemphasis time constant (default 75e-6)
+        @type tau: float
+        @param max_dev: maximum deviation in Hz (default 75e3)
+        @type max_dev: float
+
+        quad_rate must be an integer multiple of audio_rate.
+        """
+       gr.hier_block2.__init__(self, "wfm_tx",
+                               gr.io_signature(1, 1, gr.sizeof_float),      # Input signature
+                               gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
+        
+        # FIXME audio_rate and quad_rate ought to be exact rationals
+        audio_rate = int(audio_rate)
+        quad_rate = int(quad_rate)
+
+        if quad_rate % audio_rate != 0:
+            raise ValueError, "quad_rate is not an integer multiple of audio_rate"
+
+        
+        do_interp = audio_rate != quad_rate
+        
+        if do_interp:
+            interp_factor = quad_rate / audio_rate
+            interp_taps = optfir.low_pass (interp_factor,   # gain
+                                           quad_rate,       # Fs
+                                           16000,           # passband cutoff
+                                           18000,           # stopband cutoff
+                                           0.1,            # passband ripple dB
+                                           40)              # stopband atten dB
+
+            print "len(interp_taps) =", len(interp_taps)
+            self.interpolator = gr.interp_fir_filter_fff (interp_factor, interp_taps)
+
+        self.preemph = fm_preemph (quad_rate, tau=tau)
+        
+        k = 2 * math.pi * max_dev / quad_rate
+        self.modulator = gr.frequency_modulator_fc (k)
+
+        if do_interp:
+            self.connect (self, self.interpolator, self.preemph, self.modulator, self)
+        else:
+            self.connect(self, self.preemph, self.modulator, self)