examples: adding an example of using the channelizer and synthesize together to reconstruct a signal.

3 files changed, 134 insertions, 1 deletions

diff --git a/gnuradio-examples/python/pfb/CMakeLists.txt b/gnuradio-examples/python/pfb/CMakeLists.txt
index 55dbb16ac..88fdf2ead 100644
--- a/gnuradio-examples/python/pfb/CMakeLists.txt
+++ b/gnuradio-examples/python/pfb/CMakeLists.txt
@@ -29,6 +29,7 @@ GR_PYTHON_INSTALL(PROGRAMS
   resampler.py
   synth_filter.py
   synth_to_chan.py
+  reconstruction.py
   DESTINATION ${GR_PKG_DATA_DIR}/examples/pfb
   COMPONENT "gnuradio_examples"
 )
diff --git a/gnuradio-examples/python/pfb/Makefile.am b/gnuradio-examples/python/pfb/Makefile.am
index 39c81bfc2..18a024ef5 100644
--- a/gnuradio-examples/python/pfb/Makefile.am
+++ b/gnuradio-examples/python/pfb/Makefile.am
@@ -31,7 +31,8 @@ dist_ourdata_SCRIPTS =		\
 	fmtest.py		\
 	resampler.py		\
 	synth_filter.py		\
-	synth_to_chan.py
+	synth_to_chan.py	\
+	reconstruction.py
 
 dist_ourdata_DATA =		\
 	resampler_demo.grc
diff --git a/gnuradio-examples/python/pfb/reconstruction.py b/gnuradio-examples/python/pfb/reconstruction.py
new file mode 100755
index 000000000..2b6f9a831
--- /dev/null
+++ b/gnuradio-examples/python/pfb/reconstruction.py
@@ -0,0 +1,131 @@
+#!/usr/bin/env python
+
+import scipy, math, pylab
+from scipy import fftpack
+from gnuradio import gr, digital, blks2
+
+fftlen = 8192
+
+def main():
+    N = 10000
+    fs = 2000.0
+    Ts = 1.0/fs
+    t = scipy.arange(0, N*Ts, Ts)
+
+    # When playing with the number of channels, be careful about the filter
+    # specs and the channel map of the synthesizer set below.
+    nchans = 10
+
+    # Build the filter(s)
+    bw = 1000
+    tb = 400
+    proto_taps = gr.firdes.low_pass_2(1, nchans*fs, bw, tb, 80,
+                                      gr.firdes.WIN_BLACKMAN_hARRIS)
+    print "Filter length: ", len(proto_taps)
+
+
+    # Create a modulated signal
+    npwr = 0.01
+    data = scipy.random.randint(0, 256, N)
+    rrc_taps = gr.firdes.root_raised_cosine(1, 2, 1, 0.35, 41)
+
+    src = gr.vector_source_b(data.astype(scipy.uint8).tolist(), False)
+    mod = digital.bpsk_mod(samples_per_symbol=2)
+    chan = gr.channel_model(npwr)
+    rrc = gr.fft_filter_ccc(1, rrc_taps)
+
+    # Split it up into pieces
+    channelizer = blks2.pfb_channelizer_ccf(nchans, proto_taps, 2)
+    
+    # Put the pieces back together again
+    syn_taps = [nchans*t for t in proto_taps]
+    synthesizer = gr.pfb_synthesis_filterbank_ccf(nchans, syn_taps, True)
+    src_snk = gr.vector_sink_c()
+    snk = gr.vector_sink_c()
+
+    # Remap the location of the channels
+    # Can be done in synth or channelizer (watch out for rotattions in
+    # the channelizer)
+    synthesizer.set_channel_map([ 0,  1,  2,  3,  4,
+                                 15, 16, 17, 18, 19])
+    
+    tb = gr.top_block()
+    tb.connect(src, mod, chan, rrc, channelizer)
+    tb.connect(rrc, src_snk)
+
+    vsnk = []
+    for i in xrange(nchans):
+        tb.connect((channelizer,i), (synthesizer, i))
+
+        vsnk.append(gr.vector_sink_c())
+        tb.connect((channelizer,i), vsnk[i])
+        
+    tb.connect(synthesizer, snk)
+    tb.run()
+    
+    sin  = scipy.array(src_snk.data()[1000:])
+    sout = scipy.array(snk.data()[1000:])
+
+    
+    # Plot original signal
+    fs_in = nchans*fs
+    f1 = pylab.figure(1, figsize=(16,12), facecolor='w')
+    s11 = f1.add_subplot(2,2,1)
+    s11.psd(sin, NFFT=fftlen, Fs=fs_in)
+    s11.set_title("PSD of Original Signal")
+    s11.set_ylim([-200, -20])
+
+    s12 = f1.add_subplot(2,2,2)
+    s12.plot(sin.real[1000:1500], "o-b")
+    s12.plot(sin.imag[1000:1500], "o-r")
+    s12.set_title("Original Signal in Time")
+
+    start = 1
+    skip  = 4
+    s13 = f1.add_subplot(2,2,3)
+    s13.plot(sin.real[start::skip], sin.imag[start::skip], "o")
+    s13.set_title("Constellation")
+    s13.set_xlim([-2, 2])
+    s13.set_ylim([-2, 2])
+    
+    # Plot channels
+    nrows = int(scipy.sqrt(nchans))
+    ncols = int(scipy.ceil(float(nchans)/float(nrows)))
+
+    f2 = pylab.figure(2, figsize=(16,12), facecolor='w')
+    for n in xrange(nchans):
+        s = f2.add_subplot(nrows, ncols, n+1)
+        s.psd(vsnk[n].data(), NFFT=fftlen, Fs=fs_in)
+        s.set_title("Channel {0}".format(n))
+        s.set_ylim([-200, -20])
+
+    # Plot reconstructed signal
+    fs_out = 2*nchans*fs
+    f3 = pylab.figure(3, figsize=(16,12), facecolor='w')
+    s31 = f3.add_subplot(2,2,1)
+    s31.psd(sout, NFFT=fftlen, Fs=fs_out)
+    s31.set_title("PSD of Reconstructed Signal")
+    s31.set_ylim([-200, -20])
+
+    s32 = f3.add_subplot(2,2,2)
+    s32.plot(sout.real[1000:1500], "o-b")
+    s32.plot(sout.imag[1000:1500], "o-r")
+    s32.set_title("Reconstructed Signal in Time")
+
+    start = 2
+    skip  = 4
+    s33 = f3.add_subplot(2,2,3)
+    s33.plot(sout.real[start::skip], sout.imag[start::skip], "o")
+    s33.set_title("Constellation")
+    s33.set_xlim([-2, 2])
+    s33.set_ylim([-2, 2])
+
+    pylab.show()
+
+    
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass
+