Adding a test example for the synthesis filter.

diff --git a/gnuradio-examples/python/pfb/synth_filter.py b/gnuradio-examples/python/pfb/synth_filter.py
new file mode 100755 (executable)
index 0000000..b1708fd
--- /dev/null
+++ b/gnuradio-examples/python/pfb/synth_filter.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+
+from gnuradio import gr, blks2
+import scipy, pylab
+
+def main():
+    N = 1000000
+    fs = 8000
+
+    #freqs = [100, 200, 300, 400, 500]
+    freqs = [100,]
+    nchans = 7
+
+    sigs = list()
+    fmtx = list()
+    for fi in freqs:
+        s = gr.sig_source_c(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)
+
+    taps = gr.firdes.low_pass_2(len(freqs), fs, fs/float(nchans)/2, 100, 100)
+    print "Num. Taps = %d (taps per filter = %d)" % (len(taps), 
+                                                     len(taps)/nchans)
+    #filtbank = blks2.synthesis_filterbank(nchans, taps)
+    filtbank = gr.pfb_synthesis_filterbank_ccf(nchans, taps)
+
+    head = gr.head(gr.sizeof_gr_complex, N)
+    snk = gr.vector_sink_c()
+
+    tb = gr.top_block()
+    tb.connect(filtbank, head, snk)
+
+    for i,si in enumerate(sigs):
+        #tb.connect(si, fmtx[i], (filtbank, i))
+        tb.connect(si, (filtbank, i))
+    
+    tb.run()
+
+    if 0:
+        f1 = pylab.figure(1)
+        s1 = f1.add_subplot(1,1,1)
+        s1.plot(snk.data()[1000:])
+        
+        fftlen = 2048
+        f2 = pylab.figure(2)
+        s2 = f2.add_subplot(1,1,1)
+        winfunc = scipy.blackman
+        #winfunc = scipy.hamming
+        s2.psd(snk.data()[10000:], NFFT=fftlen,
+               Fs = nchans*fs,
+               noverlap=fftlen/4,
+               window = lambda d: d*winfunc(fftlen))
+
+        pylab.show()
+
+if __name__ == "__main__":
+    main()