I've recently tried out the synthesis_filterbank method provided in
filterbank.py and received unexpected results. I'm trying to use the
filterbank to create one signal from multiple baseband signals. When I use
two signals to create one output, I can see both signals using the FFT sink.
I can extract both of the channels and replay them (FM stations). However,
when I use three or four input signals, the output is three or four
copies(respectively) of one of the input signals. What's going on here?
class app_flow_graph(gr.flow_graph):
def __init__(self, options, args):
gr.flow_graph.__init__(self)
self.options = options
self.args = args
num_files = args[0]
samp_rate = args[1]
logfile = args[2]
outfile = args[3]
## Sanity
print "Num files: %d" % int(num_files)
print "Outfile: %s" % outfile
## Create low pass filter
taps = gr.firdes.low_pass(1.0, int(samp_rate), 20e3, 10e3,
gr.firdes.WIN_HANN)
print "Len taps: %d" % int(len(taps))
self.OUT = gr.file_sink(gr.sizeof_gr_complex, outfile)
self.SYN = synthesize(self, num_files, taps)
## Set input file streams
self.STREAM1 = gr.file_source(gr.sizeof_gr_complex, "nws_25kHz", 0)
self.STREAM2 = gr.file_source(gr.sizeof_gr_complex, "nws_-50kHz", 0)
self.STREAM3 = gr.file_source(gr.sizeof_gr_complex, "nws_75kHz", 0)
## Connect input to synthesis filterbank
self.connect(self.STREAM1, (self.SYN, 0))
self.connect(self.STREAM2, (self.SYN, 1))
self.connect(self.STREAM3, (self.SYN, 2))
## Connect output of filterbank to file
self.connect(self.SYN, self.OUT)
class synthesize(blks.synthesis_filterbank):
def __init__(self, fg, num_bins, taps):
blks.synthesis_filterbank.__init__(self, fg, int(num_bins), taps)
def main():
usage = "usage: %prog num_input_files logfile outfile"
parser = OptionParser(option_class=eng_option, usage=usage)
(options, args) = parser.parse_args()
if(len(args) < 4):
parser.print_help()
sys.exit(1)
fg = app_flow_graph(options, args)
try:
fg.run()
except KeyboardInterrupt:
pass
if __name__ == "__main__":
main()
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