#!/usr/bin/env python
#
-# Copyright 2009 Free Software Foundation, Inc.
+# Copyright 2009,2010 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# Boston, MA 02110-1301, USA.
#
-from gnuradio import gr
+from gnuradio import gr, optfir
class pfb_channelizer_ccf(gr.hier_block2):
'''
This simplifies the interface by allowing a single input stream to connect to this block.
It will then output a stream for each channel.
'''
- def __init__(self, numchans, taps):
+ def __init__(self, numchans, taps=None, oversample_rate=1, atten=100):
gr.hier_block2.__init__(self, "pfb_channelizer_ccf",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(numchans, numchans, gr.sizeof_gr_complex)) # Output signature
self._numchans = numchans
- self._taps = taps
+ self._oversample_rate = oversample_rate
+
+ if taps is not None:
+ self._taps = taps
+ else:
+ # Create a filter that covers the full bandwidth of the input signal
+ bw = 0.4
+ tb = 0.2
+ ripple = 0.1
+ made = False
+ while not made:
+ try:
+ self._taps = optfir.low_pass(1, self._numchans, bw, bw+tb, ripple, atten)
+ made = True
+ except RuntimeError:
+ ripple += 0.01
+ made = False
+ print("Warning: set ripple to %.4f dB. If this is a problem, adjust the attenuation or create your own filter taps." % (ripple))
+
+ # Build in an exit strategy; if we've come this far, it ain't working.
+ if(ripple >= 1.0):
+ raise RuntimeError("optfir could not generate an appropriate filter.")
self.s2ss = gr.stream_to_streams(gr.sizeof_gr_complex, self._numchans)
- self.pfb = gr.pfb_channelizer_ccf(self._numchans, self._taps)
+ self.pfb = gr.pfb_channelizer_ccf(self._numchans, self._taps,
+ self._oversample_rate)
self.v2s = gr.vector_to_streams(gr.sizeof_gr_complex, self._numchans)
self.connect(self, self.s2ss)