Work on examples for the synthesize filterbank block. The cleans up the simple example and adds a new example that synthesizes a number of signals and then channelizes them again. It displays the synthesized PSD as well as the PSD and time waveform of one of the channels that's specified in teh code.

1 files changed, 105 insertions, 0 deletions

diff --git a/gnuradio-examples/python/pfb/synth_to_chan.py b/gnuradio-examples/python/pfb/synth_to_chan.py
new file mode 100755
index 000000000..1beda1a54
--- /dev/null
+++ b/gnuradio-examples/python/pfb/synth_to_chan.py
@@ -0,0 +1,105 @@
+#!/usr/bin/env python
+#
+# Copyright 2010 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 gr, blks2
+import scipy, pylab
+
+def main():
+    N = 1000000
+    fs = 8000
+
+    freqs = [100, 200, 300, 400, 500]
+    nchans = 7
+
+    sigs = list()
+    fmtx = list()
+    for fi in freqs:
+        s = gr.sig_source_f(fs, gr.GR_SIN_WAVE, fi, 1)
+        fm = blks2.nbfm_tx (fs, 4*fs, max_dev=10000, tau=75e-6)
+        sigs.append(s)
+        fmtx.append(fm)
+
+    syntaps = gr.firdes.low_pass_2(len(freqs), fs, fs/float(nchans)/2, 100, 100)
+    print "Synthesis Num. Taps = %d (taps per filter = %d)" % (len(syntaps), 
+                                                               len(syntaps)/nchans)
+    chtaps = gr.firdes.low_pass_2(len(freqs), fs, fs/float(nchans)/2, 100, 100)
+    print "Channelizer Num. Taps = %d (taps per filter = %d)" % (len(chtaps), 
+                                                                 len(chtaps)/nchans)
+    filtbank = gr.pfb_synthesis_filterbank_ccf(nchans, syntaps)
+    channelizer = blks2.pfb_channelizer_ccf(nchans, chtaps)
+
+    noise_level = 0.01
+    head = gr.head(gr.sizeof_gr_complex, N)
+    noise = gr.noise_source_c(gr.GR_GAUSSIAN, noise_level)
+    addnoise = gr.add_cc()
+    snk_synth = gr.vector_sink_c()
+
+    tb = gr.top_block()
+
+    tb.connect(noise, (addnoise,0))
+    tb.connect(filtbank, head, (addnoise, 1))
+    tb.connect(addnoise, channelizer)
+    tb.connect(addnoise, snk_synth)
+
+    snk = list()
+    for i,si in enumerate(sigs):
+        tb.connect(si, fmtx[i], (filtbank, i))
+
+    for i in xrange(nchans):
+        snk.append(gr.vector_sink_c())
+        tb.connect((channelizer, i), snk[i])
+    
+    tb.run()
+
+    if 1:
+        channel = 1
+        data = snk[channel].data()[1000:]
+
+        f1 = pylab.figure(1)
+        s1 = f1.add_subplot(1,1,1)
+        s1.plot(data[10000:10200] )
+        s1.set_title(("Output Signal from Channel %d" % channel))
+        
+        fftlen = 2048
+        winfunc = scipy.blackman
+        #winfunc = scipy.hamming
+
+        f2 = pylab.figure(2)
+        s2 = f2.add_subplot(1,1,1)
+        s2.psd(data, NFFT=fftlen,
+               Fs = nchans*fs,
+               noverlap=fftlen/4,
+               window = lambda d: d*winfunc(fftlen))
+        s2.set_title(("Output PSD from Channel %d" % channel))
+
+        f3 = pylab.figure(3)
+        s3 = f3.add_subplot(1,1,1)
+        s3.psd(snk_synth.data()[1000:], NFFT=fftlen,
+               Fs = nchans*fs,
+               noverlap=fftlen/4,
+               window = lambda d: d*winfunc(fftlen))
+        s3.set_title("Output of Synthesis Filter")
+
+        pylab.show()
+
+if __name__ == "__main__":
+    main()