Refactored modes_rx to use a more modular radio interface (radio.py) using a pubsub pattern to formalize the old "outputs" interface I was using. Should make it easier to reuse the radio interface.

python/CMakeLists.txt

@@ -41,6 +41,7 @@ GR_PYTHON_INSTALL(
     kml.py
     parse.py
     msprint.py
+    radio.py
     raw_server.py
     rx_path.py
     sbs1.py

python/__init__.py

@@ -58,6 +58,7 @@ from sql import output_sql
 from sbs1 import output_sbs1
 from kml import output_kml
 from raw_server import raw_server
+from radio import modes_radio
 from exceptions import *
 from az_map import *
 #this is try/excepted in case the user doesn't have numpy installed

python/radio.py

@@ -0,0 +1,144 @@
+# Copyright 2013 Nick Foster
+# 
+# This file is part of gr-air-modes
+# 
+# gr-air-modes 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.
+# 
+# gr-air-modes 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 gr-air-modes; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+#
+
+# Radio interface for Mode S RX.
+# Handles all Gnuradio-related functionality.
+# You pass it options, it gives you data.
+# It uses the pubsub interface to allow clients to subscribe to its data feeds.
+
+from gnuradio import gr, gru, optfir, eng_notation, blks2
+from gnuradio.eng_option import eng_option
+from gnuradio.gr.pubsub import pubsub
+import air_modes
+
+DOWNLINK_DATA_TYPE = 'dl_data'
+
+class modes_radio (gr.top_block, pubsub):
+  def __init__(self, options):
+    gr.top_block.__init__(self)
+    pubsub.__init__(self)
+    self._options = options
+    self._queue = gr.msg_queue()
+    
+    rate = int(options.rate)
+    use_resampler = False
+    self.time_source = None
+
+    self._setup_source(options)
+
+    self.subscribe('gain', self.set_gain)
+    self.subscribe('freq', self.set_freq)
+
+    self['gain'] = options.gain
+    self['freq'] = options.freq
+    self['rate'] = options.rate
+    self['filename'] = options.filename
+
+    #TODO allow setting rate, threshold (drill down into slicer & preamble)
+
+    self.rx_path = air_modes.rx_path(rate, options.threshold, self._queue, options.pmf)
+
+    if use_resampler:
+        self.lpfiltcoeffs = gr.firdes.low_pass(1, 5*3.2e6, 1.6e6, 300e3)
+        self.resample = blks2.rational_resampler_ccf(interpolation=5, decimation=4, taps=self.lpfiltcoeffs)
+        self.connect(self._u, self.resample, self.rx_path)
+    else:
+        self.connect(self._u, self.rx_path)
+
+    #Publish messages when they come back off the queue
+    self._async_rcv = gru.msgq_runner(self._queue, self.async_callback)
+
+  def async_callback(self, msg):
+    self[DOWNLINK_DATA_TYPE] = msg.to_string()
+
+  #these are wrapped with try/except because file sources and udp sources
+  #don't have set_center_freq/set_gain functions. this should check to see
+  #the type of self._u.
+  def set_freq(self, freq):
+    try:
+        result = self._u.set_center_freq(freq, 0)
+        return result
+    except:
+        pass
+
+  def set_gain(self, gain):
+    try:
+        self._u.set_gain(gain)
+    except:
+        pass
+
+  def _setup_source(self, options):
+    if options.filename is None and options.udp is None and options.rtlsdr is None:
+      #UHD source by default
+      from gnuradio import uhd
+      self._u = uhd.single_usrp_source(options.args, uhd.io_type_t.COMPLEX_FLOAT32, 1)
+
+      if(options.subdev):
+        self._u.set_subdev_spec(options.subdev, 0)
+
+      #check for GPSDO
+      #if you have a GPSDO, UHD will automatically set the timestamp to UTC time
+      #as well as automatically set the clock to lock to GPSDO.
+      if self._u.get_time_source(0) == 'gpsdo':
+        self._time_source = 'gpsdo'
+      else:
+        self._time_source = None
+        self._u.set_time_now(uhd.time_spec(0.0))
+
+      if options.antenna is not None:
+        self._u.set_antenna(options.antenna)
+
+      self._u.set_samp_rate(rate)
+      rate = int(self._u.get_samp_rate()) #retrieve actual
+
+      if options.gain is None: #set to halfway
+        g = self._u.get_gain_range()
+        options.gain = (g.start()+g.stop()) / 2.0
+
+      print "Setting gain to %i" % options.gain
+      self._u.set_gain(options.gain)
+      print "Gain is %i" % self._u.get_gain()
+      
+    elif options.rtlsdr: #RTLSDR dongle
+        import osmosdr
+        self._u = osmosdr.source_c(options.args)
+        self._u.set_sample_rate(3.2e6) #fixed for RTL dongles
+        if not self._u.set_center_freq(options.freq):
+            print "Failed to set initial frequency"
+
+        self._u.set_gain_mode(0) #manual gain mode
+        if options.gain is None:
+            options.gain = 34
+            
+        self._u.set_gain(options.gain)
+        print "Gain is %i" % self._u.get_gain()
+
+        use_resampler = True
+                
+    else:
+      if options.filename is not None:
+        self._u = gr.file_source(gr.sizeof_gr_complex, options.filename)
+      elif options.udp is not None:
+        self._u = gr.udp_source(gr.sizeof_gr_complex, "localhost", options.udp)
+      else:
+        raise Exception("No valid source selected")
+        
+
+    print "Rate is %i" % (options.rate,)