This example application demonstrates receiving and demodulating the
FLEX pager protocol.
-A receive chain is built up of the following signal processing
-blocks:
-
-USRP - Daughter board source generating complex baseband signal.
-CHAN - Low pass filter to select channel bandwidth
-AGC - Automatic gain control leveling signal at [-1.0, +1.0]
-FLEX - FLEX pager protocol decoder
-
The following are required command line parameters:
--f FREQ USRP receive frequency
+-f FREQ USRP receive frequency
The following are optional command line parameters:
-R SUBDEV Daughter board specification, defaults to first found
+-F FILE Read samples from a file instead of USRP.
-c FREQ Calibration offset. Gets added to receive frequency.
Defaults to 0.0 Hz.
-g GAIN Daughterboard gain setting. Defaults to mid-range.
--r RFSQL RF squelch in db. Defaults to -50.0.
+-l Log flow graph to files (LOTS of data)
+-v Verbose output
Once the program is running, ctrl-break (Ctrl-C) stops operation.
"""
-class usrp_source_c(gr.hier_block):
- """
- Create a USRP source object supplying complex floats.
-
- Selects user supplied subdevice or chooses first available one.
-
- Calibration value is the offset from the tuned frequency to
- the actual frequency.
- """
- def __init__(self, fg, subdev_spec, decim, gain=None, calibration=0.0):
- self._decim = decim
- self._src = usrp.source_c()
- if subdev_spec is None:
- subdev_spec = usrp.pick_rx_subdevice(self._src)
- self._subdev = usrp.selected_subdev(self._src, subdev_spec)
- self._src.set_mux(usrp.determine_rx_mux_value(self._src, subdev_spec))
- self._src.set_decim_rate(self._decim)
-
- # If no gain specified, set to midrange
- if gain is None:
- g = self._subdev.gain_range()
- gain = (g[0]+g[1])/2.0
-
- self._subdev.set_gain(gain)
- self._cal = calibration
-
- gr.hier_block.__init__(self, fg, self._src, self._src)
-
- def tune(self, freq):
- result = usrp.tune(self._src, 0, self._subdev, freq+self._cal)
- # TODO: deal with residual
-
- def rate(self):
- return self._src.adc_rate()/self._decim
-
-class app_flow_graph(gr.flow_graph):
- def __init__(self, options, args, queue):
- gr.flow_graph.__init__(self)
+class app_top_block(gr.top_block):
+ def __init__(self, options, queue):
+ gr.top_block.__init__(self, "usrp_flex")
self.options = options
- self.args = args
-
- USRP = usrp_source_c(self, # Flow graph
- options.rx_subdev_spec, # Daugherboard spec
- 256, # IF decimation ratio gets 250K if_rate
- options.gain, # Receiver gain
- options.calibration) # Frequency offset
- USRP.tune(options.frequency)
-
- if_rate = USRP.rate()
- channel_rate = 25000
- channel_decim = int(if_rate / channel_rate)
-
- CHAN_taps = optfir.low_pass(1.0, # Filter gain
- if_rate, # Sample rate
- 8000, # One sided modulation bandwidth
- 10000, # One sided channel bandwidth
- 0.1, # Passband ripple
- 60) # Stopband attenuation
-
- CHAN = gr.freq_xlating_fir_filter_ccf(channel_decim, # Decimation rate
- CHAN_taps, # Filter taps
- 0.0, # Offset frequency
- if_rate) # Sample rate
-
- AGC = gr.agc_cc(1.0/channel_rate, # Time constant
- 1.0, # Reference power
- 1.0, # Initial gain
- 1.0) # Maximum gain
+
+ if options.from_file is None:
+ # Set up USRP source with specified RX daughterboard
+ src = usrp.source_c()
+ if options.rx_subdev_spec == None:
+ options.subdev_spec = usrp.pick_rx_subdevice(src)
+ subdev = usrp.selected_subdev(src, options.rx_subdev_spec)
+ src.set_mux(usrp.determine_rx_mux_value(src, options.rx_subdev_spec))
+
+ # Grab 250 KHz of spectrum (sample rate becomes 250 ksps complex)
+ src.set_decim_rate(256)
+
+ # If no gain specified, set to midrange
+ if options.gain is None:
+ g = subdev.gain_range()
+ options.gain = (g[0]+g[1])/2.0
+ subdev.set_gain(options.gain)
+
+ # Tune daughterboard
+ actual_frequency = options.frequency+options.calibration
+ tune_result = usrp.tune(src, 0, subdev, actual_frequency)
+ if not tune_result:
+ sys.stderr.write("Failed to set center frequency to"+`actual_frequency`+"\n")
+ sys.exit(1)
+
+ if options.verbose:
+ print "Using RX daughterboard", subdev.side_and_name()
+ print "USRP gain is", options.gain
+ print "USRP tuned to", actual_frequency
+
+ else:
+ # Use supplied file as source of samples
+ src = gr.file_source(gr.sizeof_gr_complex, options.from_file)
+ if options.verbose:
+ print "Reading samples from", options.from_file
+
+ if options.log and not options.from_file:
+ usrp_sink = gr.file_sink(gr.sizeof_gr_complex, 'usrp.dat')
+ self.connect(src, usrp_sink)
+
+ # Set up 22KHz-wide bandpass about center frequency. Decimate by 10
+ # to get channel rate of 25Ksps
+ taps = optfir.low_pass(1.0, # Filter gain
+ 250e3, # Sample rate
+ 11000, # One-sided modulation bandwidth
+ 12500, # One-sided channel bandwidth
+ 0.1, # Passband ripple
+ 60) # Stopband attenuation
- FLEX = pager.flex_demod(self, 25000, queue)
+ if options.verbose:
+ print "Channel filter has", len(taps), "taps."
+
+ chan = gr.freq_xlating_fir_filter_ccf(10, # Decimation rate
+ taps, # Filter taps
+ 0.0, # Offset frequency
+ 250e3) # Sample rate
- self.connect(USRP, CHAN, AGC, FLEX.INPUT)
+ if options.log:
+ chan_sink = gr.file_sink(gr.sizeof_gr_complex, 'chan.dat')
+ self.connect(chan, chan_sink)
+
+ # FLEX protocol demodulator
+ flex = pager.flex_demod(queue, options.frequency, options.verbose, options.log)
+
+ self.connect(src, chan, flex)
def main():
parser = OptionParser(option_class=eng_option)
help="set frequency offset to Hz", metavar="Hz")
parser.add_option("-g", "--gain", type="int", default=None,
help="set RF gain", metavar="dB")
+ parser.add_option("-l", "--log", action="store_true", default=False,
+ help="log flowgraph to files (LOTS of data)")
+ parser.add_option("-v", "--verbose", action="store_true", default=False,
+ help="display debug output")
+ parser.add_option("-F", "--from-file", default=None,
+ help="read samples from file instead of USRP")
(options, args) = parser.parse_args()
- if len(args) > 0 or options.frequency == None:
+ if len(args) > 0 or (options.frequency == None and options.from_file == None):
print "Run 'usrp_flex.py -h' for options."
sys.exit(1)
- if options.frequency < 1e6:
- options.frequency *= 1e6
-
- queue = gr.msg_queue()
+ if options.frequency == None:
+ options.frequency = 0.0
- fg = app_flow_graph(options, args, queue)
+ # Flow graph emits pages into message queue
+ queue = gr.msg_queue()
+ tb = app_top_block(options, queue)
+ r = gr.runtime(tb)
+
try:
- fg.start()
+ r.start()
while 1:
if not queue.empty_p():
msg = queue.delete_head() # Blocking read
time.sleep(1)
except KeyboardInterrupt:
- fg.stop()
+ r.stop()
if __name__ == "__main__":
main()
projects / debian / gnuradio / blobdiff