# Boston, MA 02110-1301, USA.
#
-from gnuradio import gr
+from gnuradio import gr, optfir
class pfb_interpolator_ccf(gr.hier_block2):
'''
streams. This block is provided to be consistent with the interface to the
other PFB block.
'''
- def __init__(self, interp, taps):
+ def __init__(self, interp, taps=None, atten=100):
gr.hier_block2.__init__(self, "pfb_interpolator_ccf",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
self._interp = interp
self._taps = taps
+ 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 = 0.99
+ made = False
+ while not made:
+ try:
+ self._taps = optfir.low_pass(self._interp, self._interp, 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.pfb = gr.pfb_interpolator_ccf(self._interp, self._taps)
self.connect(self, self.pfb)