New usrp_wfm_rcv_sca.py example from Eric A. Cottrell (WB1HBHU)

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4276 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 399 insertions, 0 deletions

diff --git a/gnuradio-examples/python/usrp/usrp_wfm_rcv_sca.py b/gnuradio-examples/python/usrp/usrp_wfm_rcv_sca.py
new file mode 100644
index 000000000..640ffe872
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+++ b/gnuradio-examples/python/usrp/usrp_wfm_rcv_sca.py
@@ -0,0 +1,399 @@
+#!/usr/bin/env python
+#
+# Copyright 2006,2007 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 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 this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+
+"""
+Here is a bit of code that will receive SCA analog subcarriers of FM
+Broadcast Stations using the USRP.  It is a modified version of
+usrp_wfm_rcv.py.
+
+Common SCA frequencies are 67 kHz and 92 kHz.  SCA is used for Reading
+Services for the Blind, Background Music, Foreign Language Services, and
+other services.  Remember you may hear static when tuned to a FM station
+because this code only outputs SCA audio.
+
+The USRP gain is critical for good decoding.  Adjust for minimum noise.
+ I use the Post FM Demod FFT to check for SCA subcarriers and to adjust
+the USRP gain for the lowest noise floor.  The stereo pilot at 19 KHz,
+the stereo difference signal around 38 KHz, and RDS at 57 KHz are also
+displayed on the Post FM Demod FFT if present.
+
+The range below 67 kHz is used for SCA only when Stereo is not used.
+
+The SCA recieve range is not as far as the main FM carrier receive range
+so tune in strong local stations first.
+
+I tried to comment the code with the various parameters.  There seems to
+be several choices for a couple of them.  I coded the common ones I see
+here.
+
+In the local area there are a couple of stations using digital SCA.
+These look similar to narrow DRM signals and I wonder if they are using
+OFDM.
+"""
+
+
+from gnuradio import gr, gru, eng_notation, optfir
+from gnuradio import audio
+from gnuradio import usrp
+from gnuradio import blks
+from gnuradio.blksimpl.fm_emph import fm_deemph
+from gnuradio.eng_option import eng_option
+from gnuradio.wxgui import slider, powermate
+from gnuradio.wxgui import stdgui, fftsink, form
+from optparse import OptionParser
+import usrp_dbid
+import sys
+import math
+import wx
+
+def pick_subdevice(u):
+    """
+    The user didn't specify a subdevice on the command line.
+    Try for one of these, in order: TV_RX, BASIC_RX, whatever is on side A.
+
+    @return a subdev_spec
+    """
+    return usrp.pick_subdev(u, (usrp_dbid.TV_RX,
+                                usrp_dbid.TV_RX_REV_2,
+                                usrp_dbid.BASIC_RX))
+
+
+class wfm_rx_sca_graph (stdgui.gui_flow_graph):
+    def __init__(self,frame,panel,vbox,argv):
+        stdgui.gui_flow_graph.__init__ (self,frame,panel,vbox,argv)
+
+        parser=OptionParser(option_class=eng_option)
+        parser.add_option("-R", "--rx-subdev-spec", type="subdev", default=None,
+                          help="select USRP Rx side A or B (default=A)")
+        parser.add_option("-f", "--freq", type="eng_float", default=100.1e6,
+                          help="set frequency to FREQ", metavar="FREQ")
+        parser.add_option("-g", "--gain", type="eng_float", default=40,
+                          help="set gain in dB (default is midpoint)")
+        parser.add_option("-V", "--volume", type="eng_float", default=None,
+                          help="set volume (default is midpoint)")
+        parser.add_option("-O", "--audio-output", type="string", default="",
+                          help="pcm device name.  E.g., hw:0,0 or surround51 or /dev/dsp")
+
+        (options, args) = parser.parse_args()
+        if len(args) != 0:
+            parser.print_help()
+            sys.exit(1)
+
+        self.frame = frame
+        self.panel = panel
+
+        self.vol = 0
+        self.state = "FREQ"
+        self.freq = 0
+
+        # build graph
+
+        self.u = usrp.source_c()                    # usrp is data source
+
+        adc_rate = self.u.adc_rate()                # 64 MS/s
+        usrp_decim = 200
+        self.u.set_decim_rate(usrp_decim)
+        usrp_rate = adc_rate / usrp_decim           # 320 kS/s
+        chanfilt_decim = 1
+        demod_rate = usrp_rate / chanfilt_decim
+        sca_chanfilt_decim = 5
+        sca_demod_rate = demod_rate / sca_chanfilt_decim  #64 kHz
+        audio_decimation = 2
+        audio_rate = sca_demod_rate / audio_decimation  # 32 kHz
+
+        if options.rx_subdev_spec is None:
+            options.rx_subdev_spec = pick_subdevice(self.u)
+
+        self.u.set_mux(usrp.determine_rx_mux_value(self.u, options.rx_subdev_spec))
+        self.subdev = usrp.selected_subdev(self.u, options.rx_subdev_spec)
+        print "Using RX d'board %s" % (self.subdev.side_and_name(),)
+
+        #Create filter to get main FM Channel we want
+        chan_filt_coeffs = optfir.low_pass (1,           # gain
+                                            usrp_rate,   # sampling rate
+                                            100e3,        # passband cutoff
+                                            140e3,       # stopband cutoff
+                                            0.1,         # passband ripple
+                                            60)          # stopband attenuation
+        #print len(chan_filt_coeffs)
+        chan_filt = gr.fir_filter_ccf (chanfilt_decim, chan_filt_coeffs)
+
+        #Create demodulator block for Main FM Channel
+	max_dev = 75e3
+        fm_demod_gain = demod_rate/(2*math.pi*max_dev)
+        self.fm_demod = gr.quadrature_demod_cf (fm_demod_gain)
+
+        # Note - deemphasis is not applied to the Main FM Channel as main audio is not decoded
+
+        # SCA Devation is 10% of carrier but some references say 20% if mono with one SCA (6 KHz seems typical)
+        max_sca_dev = 6e3
+
+	# Create filter to get SCA channel we want
+        sca_chan_coeffs = gr.firdes.low_pass (1.0,                # gain
+                                          demod_rate,       # sampling rate
+                                          max_sca_dev,      # low pass cutoff freq
+                                          max_sca_dev/3,    # width of trans. band
+                                          gr.firdes.WIN_HANN) # filter type
+
+        self.ddc = gr.freq_xlating_fir_filter_fcf(sca_chanfilt_decim,       # decimation rate
+                                                  sca_chan_coeffs,    # taps
+                                                  0,              # frequency translation amount (Gets set by the UI)
+                                                  demod_rate)   # input sample rate
+
+        #Create demodulator block for SCA Channel
+        sca_demod_gain = sca_demod_rate/(2*math.pi*max_sca_dev)
+        self.fm_demod_sca = gr.quadrature_demod_cf (sca_demod_gain)
+
+
+        # SCA analog audio is bandwidth limited to 5 KHz
+        max_sca_audio_freq = 5.0e3
+        # SCA analog deephasis is 150 uS (75 uS may be used)
+        sca_tau = 150e-6
+
+        # compute FIR filter taps for SCA audio filter
+        audio_coeffs = gr.firdes.low_pass (1.0,         # gain
+                                           sca_demod_rate,      # sampling rate
+                                           max_sca_audio_freq, # low pass cutoff freq
+                                           max_sca_audio_freq/2.5,             # width of trans. band
+                                           gr.firdes.WIN_HAMMING)
+
+        # input: float; output: float
+        self.audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
+
+	# Create deemphasis block that is applied after SCA demodulation
+        self.deemph = fm_deemph (self, audio_rate, sca_tau)
+
+        self.volume_control = gr.multiply_const_ff(self.vol)
+
+        # sound card as final sink
+        audio_sink = audio.sink (int (audio_rate),
+                                 options.audio_output,
+                                 False)  # ok_to_block
+
+        # now wire it all together
+        self.connect (self.u, chan_filt, self.fm_demod, self.ddc, self.fm_demod_sca)
+        self.connect (self.fm_demod_sca, self.audio_filter, self.deemph, self.volume_control, audio_sink)
+
+        self._build_gui(vbox, usrp_rate, demod_rate, sca_demod_rate, audio_rate)
+
+        if options.gain is None:
+            # if no gain was specified, use the mid-point in dB
+            g = self.subdev.gain_range()
+            options.gain = float(g[0]+g[1])/2
+
+        if options.volume is None:
+            g = self.volume_range()
+            options.volume = float(g[0]+g[1])/2
+
+        if abs(options.freq) < 1e6:
+            options.freq *= 1e6
+
+        # set initial values
+
+        self.set_gain(options.gain)
+        self.set_vol(options.volume)
+        if not(self.set_freq(options.freq)):
+            self._set_status_msg("Failed to set initial frequency")
+        self.set_sca_freq(67000)  # A common SCA Frequency
+
+
+    def _set_status_msg(self, msg, which=0):
+        self.frame.GetStatusBar().SetStatusText(msg, which)
+
+
+    def _build_gui(self, vbox, usrp_rate, demod_rate, sca_demod_rate, audio_rate):
+
+        def _form_set_freq(kv):
+            return self.set_freq(kv['freq'])
+
+        def _form_set_sca_freq(kv):
+            return self.set_sca_freq(kv['sca_freq'])
+
+        if 1:
+            self.src_fft = fftsink.fft_sink_c (self, self.panel, title="Data from USRP",
+                                               fft_size=512, sample_rate=usrp_rate)
+            self.connect (self.u, self.src_fft)
+            vbox.Add (self.src_fft.win, 4, wx.EXPAND)
+
+        if 1:
+            post_demod_fft = fftsink.fft_sink_f (self, self.panel, title="Post FM Demod",
+                                                fft_size=2048, sample_rate=demod_rate,
+                                                y_per_div=10, ref_level=0)
+            self.connect (self.fm_demod, post_demod_fft)
+            vbox.Add (post_demod_fft.win, 4, wx.EXPAND)
+
+        if 0:
+            post_demod_sca_fft = fftsink.fft_sink_f (self, self.panel, title="Post SCA Demod",
+                                                fft_size=1024, sample_rate=sca_demod_rate,
+                                                y_per_div=10, ref_level=0)
+            self.connect (self.fm_demod_sca, post_demod_sca_fft)
+            vbox.Add (post_demod_sca_fft.win, 4, wx.EXPAND)
+
+        if 0:
+            post_deemph_fft = fftsink.fft_sink_f (self, self.panel, title="Post SCA Deemph",
+                                                  fft_size=512, sample_rate=audio_rate,
+                                                  y_per_div=10, ref_level=-20)
+            self.connect (self.deemph, post_deemph_fft)
+            vbox.Add (post_deemph_fft.win, 4, wx.EXPAND)
+
+
+        # control area form at bottom
+        self.myform = myform = form.form()
+
+        hbox = wx.BoxSizer(wx.HORIZONTAL)
+        hbox.Add((5,0), 0)
+        myform['freq'] = form.float_field(
+            parent=self.panel, sizer=hbox, label="Freq", weight=1,
+            callback=myform.check_input_and_call(_form_set_freq, self._set_status_msg))
+
+        hbox.Add((5,0), 0)
+        myform['freq_slider'] = \
+            form.quantized_slider_field(parent=self.panel, sizer=hbox, weight=3,
+                                        range=(87.9e6, 108.1e6, 0.1e6),
+                                        callback=self.set_freq)
+        hbox.Add((5,0), 0)
+        vbox.Add(hbox, 0, wx.EXPAND)
+
+        hbox = wx.BoxSizer(wx.HORIZONTAL)
+        hbox.Add((5,0), 0)
+        myform['sca_freq'] = form.float_field(
+            parent=self.panel, sizer=hbox, label="SCA", weight=1,
+            callback=myform.check_input_and_call(_form_set_sca_freq, self._set_status_msg))
+
+        hbox.Add((5,0), 0)
+        myform['sca_freq_slider'] = \
+            form.quantized_slider_field(parent=self.panel, sizer=hbox, weight=3,
+                                        range=(38e3, 100e3, 1.0e3),
+                                        callback=self.set_sca_freq)
+        hbox.Add((5,0), 0)
+        vbox.Add(hbox, 0, wx.EXPAND)
+
+        hbox = wx.BoxSizer(wx.HORIZONTAL)
+        hbox.Add((5,0), 0)
+
+        myform['volume'] = \
+            form.quantized_slider_field(parent=self.panel, sizer=hbox, label="Volume",
+                                        weight=3, range=self.volume_range(),
+                                        callback=self.set_vol)
+        hbox.Add((5,0), 1)
+
+        myform['gain'] = \
+            form.quantized_slider_field(parent=self.panel, sizer=hbox, label="Gain",
+                                        weight=3, range=self.subdev.gain_range(),
+                                        callback=self.set_gain)
+        hbox.Add((5,0), 0)
+        vbox.Add(hbox, 0, wx.EXPAND)
+
+        try:
+            self.knob = powermate.powermate(self.frame)
+            self.rot = 0
+            powermate.EVT_POWERMATE_ROTATE (self.frame, self.on_rotate)
+            powermate.EVT_POWERMATE_BUTTON (self.frame, self.on_button)
+        except:
+            print "FYI: No Powermate or Contour Knob found"
+
+
+    def on_rotate (self, event):
+        self.rot += event.delta
+        if (self.state == "FREQ"):
+            if self.rot >= 3:
+                self.set_freq(self.freq + .1e6)
+                self.rot -= 3
+            elif self.rot <=-3:
+                self.set_freq(self.freq - .1e6)
+                self.rot += 3
+        else:
+            step = self.volume_range()[2]
+            if self.rot >= 3:
+                self.set_vol(self.vol + step)
+                self.rot -= 3
+            elif self.rot <=-3:
+                self.set_vol(self.vol - step)
+                self.rot += 3
+
+    def on_button (self, event):
+        if event.value == 0:        # button up
+            return
+        self.rot = 0
+        if self.state == "FREQ":
+            self.state = "VOL"
+        else:
+            self.state = "FREQ"
+        self.update_status_bar ()
+
+
+    def set_vol (self, vol):
+        g = self.volume_range()
+        self.vol = max(g[0], min(g[1], vol))
+        self.volume_control.set_k(10**(self.vol/10))
+        self.myform['volume'].set_value(self.vol)
+        self.update_status_bar ()
+
+    def set_freq(self, target_freq):
+        """
+        Set the center frequency we're interested in.
+
+        @param target_freq: frequency in Hz
+        @rypte: bool
+
+        Tuning is a two step process.  First we ask the front-end to
+        tune as close to the desired frequency as it can.  Then we use
+        the result of that operation and our target_frequency to
+        determine the value for the digital down converter.
+        """
+        r = usrp.tune(self.u, 0, self.subdev, target_freq)
+
+        if r:
+            self.freq = target_freq
+            self.myform['freq'].set_value(target_freq)         # update displayed value
+            self.myform['freq_slider'].set_value(target_freq)  # update displayed value
+            self.update_status_bar()
+            self._set_status_msg("OK", 0)
+            return True
+
+        self._set_status_msg("Failed", 0)
+        return False
+
+    def set_sca_freq(self, target_sca_freq):
+
+        self.ddc.set_center_freq(-target_sca_freq)
+        self.myform['sca_freq'].set_value(target_sca_freq)         # update displayed value
+        self.myform['sca_freq_slider'].set_value(target_sca_freq)  # update displayed value
+        self.update_status_bar()
+        self._set_status_msg("OK", 0)
+        return True
+
+    def set_gain(self, gain):
+        self.myform['gain'].set_value(gain)     # update displayed value
+        self.subdev.set_gain(gain)
+
+    def update_status_bar (self):
+        msg = "Volume:%r  Setting:%s" % (self.vol, self.state)
+        self._set_status_msg(msg, 1)
+        self.src_fft.set_baseband_freq(self.freq)
+
+    def volume_range(self):
+        return (-20.0, 0.0, 0.5)
+
+
+if __name__ == '__main__':
+    app = stdgui.stdapp (wfm_rx_sca_graph, "USRP WFM SCA RX")
+    app.MainLoop ()