1 files changed, 116 insertions, 0 deletions
diff --git a/gr-digital/examples/example_costas.py b/gr-digital/examples/example_costas.py
new file mode 100755
index 000000000..aef0196cc
--- /dev/null
+++ b/gr-digital/examples/example_costas.py
@@ -0,0 +1,116 @@
+#!/usr/bin/env python
+
+from gnuradio import gr, digital
+from gnuradio import eng_notation
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+try:
+    import scipy
+except ImportError:
+    print "Error: could not import scipy (http://www.scipy.org/)"
+    sys.exit(1)
+
+try:
+    import pylab
+except ImportError:
+    print "Error: could not import pylab (http://matplotlib.sourceforge.net/)"
+    sys.exit(1)
+
+class example_costas(gr.top_block):
+    def __init__(self, N, sps, rolloff, ntaps, bw, noise, foffset, toffset, poffset):
+        gr.top_block.__init__(self)
+
+        rrc_taps = gr.firdes.root_raised_cosine(
+            sps, sps, 1.0, rolloff, ntaps)
+
+        data = 2.0*scipy.random.randint(0, 2, N) - 1.0
+        data = scipy.exp(1j*poffset) * data
+
+        self.src = gr.vector_source_c(data.tolist(), False)
+        self.rrc = gr.interp_fir_filter_ccf(sps, rrc_taps)
+        self.chn = gr.channel_model(noise, foffset, toffset)
+        self.cst = digital.costas_loop_cc(bw, 2)
+
+        self.vsnk_src = gr.vector_sink_c()
+        self.vsnk_cst = gr.vector_sink_c()
+        self.vsnk_frq = gr.vector_sink_f()
+
+        self.connect(self.src, self.rrc, self.chn, self.cst, self.vsnk_cst)
+        self.connect(self.rrc, self.vsnk_src)
+        self.connect((self.cst,1), self.vsnk_frq)
+
+def main():
+    parser = OptionParser(option_class=eng_option, conflict_handler="resolve")
+    parser.add_option("-N", "--nsamples", type="int", default=2000,
+                      help="Set the number of samples to process [default=%default]")
+    parser.add_option("-S", "--sps", type="int", default=4,
+                      help="Set the samples per symbol [default=%default]")
+    parser.add_option("-r", "--rolloff", type="eng_float", default=0.35,
+                      help="Set the rolloff factor [default=%default]")
+    parser.add_option("-W", "--bandwidth", type="eng_float", default=2*scipy.pi/100.0,
+                      help="Set the loop bandwidth [default=%default]")
+    parser.add_option("-n", "--ntaps", type="int", default=45,
+                      help="Set the number of taps in the filters [default=%default]")
+    parser.add_option("", "--noise", type="eng_float", default=0.0,
+                      help="Set the simulation noise voltage [default=%default]")
+    parser.add_option("-f", "--foffset", type="eng_float", default=0.0,
+                      help="Set the simulation's normalized frequency offset (in Hz) [default=%default]")
+    parser.add_option("-t", "--toffset", type="eng_float", default=1.0,
+                      help="Set the simulation's timing offset [default=%default]")
+    parser.add_option("-p", "--poffset", type="eng_float", default=0.707,
+                      help="Set the simulation's phase offset [default=%default]")
+    (options, args) = parser.parse_args ()
+
+    # Adjust N for the interpolation by sps
+    options.nsamples = options.nsamples // options.sps
+
+    # Set up the program-under-test
+    put = example_costas(options.nsamples, options.sps, options.rolloff,
+                         options.ntaps, options.bandwidth, options.noise,
+                         options.foffset, options.toffset, options.poffset)
+    put.run()
+
+    data_src = scipy.array(put.vsnk_src.data())
+
+    # Convert the FLL's LO frequency from rads/sec to Hz
+    data_frq = scipy.array(put.vsnk_frq.data()) / (2.0*scipy.pi)
+
+    # adjust this to align with the data.
+    data_cst = scipy.array(3*[0,]+list(put.vsnk_cst.data()))
+    
+    # Plot the Costas loop's LO frequency
+    f1 = pylab.figure(1, figsize=(12,10), facecolor='w')
+    s1 = f1.add_subplot(2,2,1)
+    s1.plot(data_frq)
+    s1.set_title("Costas LO")
+    s1.set_xlabel("Samples")
+    s1.set_ylabel("Frequency (normalized Hz)")
+
+    # Plot the IQ symbols
+    s3 = f1.add_subplot(2,2,2)
+    s3.plot(data_src.real, data_src.imag, "o")
+    s3.plot(data_cst.real, data_cst.imag, "rx")
+    s3.set_title("IQ")
+    s3.set_xlabel("Real part")
+    s3.set_ylabel("Imag part")
+    s3.set_xlim([-2, 2])
+    s3.set_ylim([-2, 2])
+
+    # Plot the symbols in time
+    s4 = f1.add_subplot(2,2,3)
+    s4.set_position([0.125, 0.05, 0.775, 0.4])
+    s4.plot(data_src.real, "o-")
+    s4.plot(data_cst.real, "rx-")
+    s4.set_title("Symbols")
+    s4.set_xlabel("Samples")
+    s4.set_ylabel("Real Part of Signals")
+
+    pylab.show()
+    
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass
+