tags: updated uhd_burst_detector with a better energy detector. Works well when receiving bursty NBFM signals.

1 files changed, 43 insertions, 23 deletions

diff --git a/gnuradio-examples/python/tags/uhd_burst_detector.py b/gnuradio-examples/python/tags/uhd_burst_detector.py
index f8ebbe66a..ffa419562 100755
--- a/gnuradio-examples/python/tags/uhd_burst_detector.py
+++ b/gnuradio-examples/python/tags/uhd_burst_detector.py
@@ -1,4 +1,24 @@
 #!/usr/bin/env python
+#
+# Copyright 2011 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.
+# 
 
 from gnuradio import eng_notation
 from gnuradio import gr
@@ -9,16 +29,16 @@ from gnuradio.gr import firdes
 from optparse import OptionParser
 
 class uhd_burst_detector(gr.top_block):
-    def __init__(self, frequency, sample_rate,
-                 uhd_address="192.168.10.2", trigger=False):
+    def __init__(self, uhd_address, options):
 
         gr.top_block.__init__(self)
 
-        self.freq = frequency
-        self.samp_rate = sample_rate
         self.uhd_addr = uhd_address
-        self.gain = 32
-        self.trigger = trigger
+        self.freq = options.freq
+        self.samp_rate = options.samp_rate
+        self.gain = options.gain
+        self.threshold = options.threshold
+        self.trigger = options.trigger
         
         self.uhd_src = uhd.single_usrp_source(
             device_addr=self.uhd_addr,
@@ -32,7 +52,6 @@ class uhd_burst_detector(gr.top_block):
 
         taps = firdes.low_pass_2(1, 1, 0.4, 0.1, 60)
         self.chanfilt = gr.fir_filter_ccc(10, taps)
-        self.ann0 = gr.annotator_alltoall(100000, gr.sizeof_gr_complex)
         self.tagger = gr.burst_tagger(gr.sizeof_gr_complex)
 
         # Dummy signaler to collect a burst on known periods
@@ -40,11 +59,18 @@ class uhd_burst_detector(gr.top_block):
         self.signal = gr.vector_source_s(data, True)
 
         # Energy detector to get signal burst
+        ## use squelch to detect energy
+        self.det  = gr.simple_squelch_cc(self.threshold, 0.01)
+        ## convert to mag squared (float)
         self.c2m = gr.complex_to_mag_squared()
-        self.iir = gr.single_pole_iir_filter_ff(0.0001)
-        self.sub = gr.sub_ff()
-        self.mult = gr.multiply_const_ff(32768)
+        ## average to debounce
+        self.avg = gr.single_pole_iir_filter_ff(0.01)
+        ## rescale signal for conversion to short
+        self.scale = gr.multiply_const_ff(2**16)
+        ## signal input uses shorts
         self.f2s = gr.float_to_short()
+
+        # Use file sink burst tagger to capture bursts
         self.fsnk = gr.tagged_file_sink(gr.sizeof_gr_complex, self.samp_rate)
         
 
@@ -60,17 +86,12 @@ class uhd_burst_detector(gr.top_block):
 
         else:
             # Connect an energy detector signaler to the burst tagger
-            self.connect((self.uhd_src, 0), (self.c2m, 0))
-            self.connect((self.c2m, 0), (self.sub, 0))
-            self.connect((self.c2m, 0), (self.iir, 0))
-            self.connect((self.iir, 0), (self.sub, 1))
-            self.connect((self.sub, 0), (self.mult,0))
-            self.connect((self.mult, 0), (self.f2s, 0))
-            self.connect((self.f2s, 0), (self.tagger, 1))
+            self.connect(self.uhd_src, self.det)
+            self.connect(self.det, self.c2m, self.avg, self.scale, self.f2s)
+            self.connect(self.f2s, (self.tagger, 1))
         
     def set_samp_rate(self, samp_rate):
         self.samp_rate = samp_rate
-        self.wxgui_fftsink2_0.set_sample_rate(self.samp_rate/10)
         self.uhd_src_0.set_samp_rate(self.samp_rate)
             
 if __name__ == '__main__':
@@ -83,16 +104,15 @@ if __name__ == '__main__':
                       help="set frequency to FREQ", metavar="FREQ")
     parser.add_option("-g", "--gain", type="eng_float", default=0,
                       help="set gain in dB [default=%default]")
-    parser.add_option("-R", "--rate", type="eng_float", default=200000,
+    parser.add_option("-R", "--samp-rate", type="eng_float", default=200000,
                       help="set USRP sample rate [default=%default]")
+    parser.add_option("-t", "--threshold", type="float", default=-60,
+                      help="Set the detection power threshold (dBm) [default=%default")
     parser.add_option("-T", "--trigger", action="store_true", default=False,
                       help="Use internal trigger instead of detector [default=%default]")
     (options, args) = parser.parse_args()
     
-    frequency = options.freq
-    samp_rate = samp_rate = options.rate
     uhd_addr = options.address
-    trigger = options.trigger
 
-    tb = uhd_burst_detector(frequency, samp_rate, uhd_addr, trigger)
+    tb = uhd_burst_detector(uhd_addr, options)
     tb.run()