diff options
| -rw-r--r-- | gr-filter/python/CMakeLists.txt | 2 | ||||
| -rw-r--r-- | gr-filter/python/__init__.py | 2 | ||||
| -rw-r--r-- | gr-filter/python/optfir.py | 339 | ||||
| -rw-r--r-- | gr-filter/python/pfb.py | 203 | ||||
| -rw-r--r-- | gr-filter/python/rational_resampler.py | 131 |
5 files changed, 674 insertions, 3 deletions
diff --git a/gr-filter/python/CMakeLists.txt b/gr-filter/python/CMakeLists.txt index 99a1aa3a9..07f03fac4 100644 --- a/gr-filter/python/CMakeLists.txt +++ b/gr-filter/python/CMakeLists.txt @@ -23,7 +23,9 @@ include(GrPython) GR_PYTHON_INSTALL( FILES __init__.py + optfir.py pfb.py + rational_resampler.py DESTINATION ${GR_PYTHON_DIR}/gnuradio/filter COMPONENT "filter_python" ) diff --git a/gr-filter/python/__init__.py b/gr-filter/python/__init__.py index 90b5ce0a4..65a62d828 100644 --- a/gr-filter/python/__init__.py +++ b/gr-filter/python/__init__.py @@ -25,4 +25,6 @@ processing blocks for FILTER and related functions. ''' from filter_swig import * +from rational_resampler import * import pfb +import optfir diff --git a/gr-filter/python/optfir.py b/gr-filter/python/optfir.py new file mode 100644 index 000000000..bccb8c68d --- /dev/null +++ b/gr-filter/python/optfir.py @@ -0,0 +1,339 @@ +# +# Copyright 2004,2005,2009 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. +# + +''' +Routines for designing optimal FIR filters. + +For a great intro to how all this stuff works, see section 6.6 of +"Digital Signal Processing: A Practical Approach", Emmanuael C. Ifeachor +and Barrie W. Jervis, Adison-Wesley, 1993. ISBN 0-201-54413-X. +''' + +import math, cmath +import filter_swig as filter + +# ---------------------------------------------------------------- + +## Builds a low pass filter. +# @param gain Filter gain in the passband (linear) +# @param Fs Sampling rate (sps) +# @param freq1 End of pass band (in Hz) +# @param freq2 Start of stop band (in Hz) +# @param passband_ripple_db Pass band ripple in dB (should be small, < 1) +# @param stopband_atten_db Stop band attenuation in dB (should be large, >= 60) +# @param nextra_taps Extra taps to use in the filter (default=2) +def low_pass (gain, Fs, freq1, freq2, passband_ripple_db, stopband_atten_db, + nextra_taps=2): + passband_dev = passband_ripple_to_dev (passband_ripple_db) + stopband_dev = stopband_atten_to_dev (stopband_atten_db) + desired_ampls = (gain, 0) + (n, fo, ao, w) = remezord ([freq1, freq2], desired_ampls, + [passband_dev, stopband_dev], Fs) + # The remezord typically under-estimates the filter order, so add 2 taps by default + taps = filter.pm_remez (n + nextra_taps, fo, ao, w, "bandpass") + return taps + +## Builds a band pass filter. +# @param gain Filter gain in the passband (linear) +# @param Fs Sampling rate (sps) +# @param freq_sb1 End of stop band (in Hz) +# @param freq_pb1 Start of pass band (in Hz) +# @param freq_pb2 End of pass band (in Hz) +# @param freq_sb2 Start of stop band (in Hz) +# @param passband_ripple_db Pass band ripple in dB (should be small, < 1) +# @param stopband_atten_db Stop band attenuation in dB (should be large, >= 60) +# @param nextra_taps Extra taps to use in the filter (default=2) +def band_pass (gain, Fs, freq_sb1, freq_pb1, freq_pb2, freq_sb2, + passband_ripple_db, stopband_atten_db, + nextra_taps=2): + passband_dev = passband_ripple_to_dev (passband_ripple_db) + stopband_dev = stopband_atten_to_dev (stopband_atten_db) + desired_ampls = (0, gain, 0) + desired_freqs = [freq_sb1, freq_pb1, freq_pb2, freq_sb2] + desired_ripple = [stopband_dev, passband_dev, stopband_dev] + (n, fo, ao, w) = remezord (desired_freqs, desired_ampls, + desired_ripple, Fs) + # The remezord typically under-estimates the filter order, so add 2 taps by default + taps = filter.pm_remez (n + nextra_taps, fo, ao, w, "bandpass") + return taps + + +## Builds a band pass filter with complex taps by making an LPF and +# spinning it up to the right center frequency +# @param gain Filter gain in the passband (linear) +# @param Fs Sampling rate (sps) +# @param freq_sb1 End of stop band (in Hz) +# @param freq_pb1 Start of pass band (in Hz) +# @param freq_pb2 End of pass band (in Hz) +# @param freq_sb2 Start of stop band (in Hz) +# @param passband_ripple_db Pass band ripple in dB (should be small, < 1) +# @param stopband_atten_db Stop band attenuation in dB (should be large, >= 60) +# @param nextra_taps Extra taps to use in the filter (default=2) +def complex_band_pass (gain, Fs, freq_sb1, freq_pb1, freq_pb2, freq_sb2, + passband_ripple_db, stopband_atten_db, + nextra_taps=2): + center_freq = (freq_pb2 + freq_pb1) / 2.0 + lp_pb = (freq_pb2 - center_freq)/1.0 + lp_sb = freq_sb2 - center_freq + lptaps = low_pass(gain, Fs, lp_pb, lp_sb, passband_ripple_db, + stopband_atten_db, nextra_taps) + spinner = [cmath.exp(2j*cmath.pi*center_freq/Fs*i) for i in xrange(len(lptaps))] + taps = [s*t for s,t in zip(spinner, lptaps)] + return taps + + +## Builds a band reject filter +# spinning it up to the right center frequency +# @param gain Filter gain in the passband (linear) +# @param Fs Sampling rate (sps) +# @param freq_pb1 End of pass band (in Hz) +# @param freq_sb1 Start of stop band (in Hz) +# @param freq_sb2 End of stop band (in Hz) +# @param freq_pb2 Start of pass band (in Hz) +# @param passband_ripple_db Pass band ripple in dB (should be small, < 1) +# @param stopband_atten_db Stop band attenuation in dB (should be large, >= 60) +# @param nextra_taps Extra taps to use in the filter (default=2) +def band_reject (gain, Fs, freq_pb1, freq_sb1, freq_sb2, freq_pb2, + passband_ripple_db, stopband_atten_db, + nextra_taps=2): + passband_dev = passband_ripple_to_dev (passband_ripple_db) + stopband_dev = stopband_atten_to_dev (stopband_atten_db) + desired_ampls = (gain, 0, gain) + desired_freqs = [freq_pb1, freq_sb1, freq_sb2, freq_pb2] + desired_ripple = [passband_dev, stopband_dev, passband_dev] + (n, fo, ao, w) = remezord (desired_freqs, desired_ampls, + desired_ripple, Fs) + # Make sure we use an odd number of taps + if((n+nextra_taps)%2 == 1): + n += 1 + # The remezord typically under-estimates the filter order, so add 2 taps by default + taps = filter.pm_remez (n + nextra_taps, fo, ao, w, "bandpass") + return taps + + +## Builds a high pass filter. +# @param gain Filter gain in the passband (linear) +# @param Fs Sampling rate (sps) +# @param freq1 End of stop band (in Hz) +# @param freq2 Start of pass band (in Hz) +# @param passband_ripple_db Pass band ripple in dB (should be small, < 1) +# @param stopband_atten_db Stop band attenuation in dB (should be large, >= 60) +# @param nextra_taps Extra taps to use in the filter (default=2) +def high_pass (gain, Fs, freq1, freq2, passband_ripple_db, stopband_atten_db, + nextra_taps=2): + passband_dev = passband_ripple_to_dev (passband_ripple_db) + stopband_dev = stopband_atten_to_dev (stopband_atten_db) + desired_ampls = (0, 1) + (n, fo, ao, w) = remezord ([freq1, freq2], desired_ampls, + [stopband_dev, passband_dev], Fs) + # For a HPF, we need to use an odd number of taps + # In filter.remez, ntaps = n+1, so n must be even + if((n+nextra_taps)%2 == 1): + n += 1 + + # The remezord typically under-estimates the filter order, so add 2 taps by default + taps = filter.pm_remez (n + nextra_taps, fo, ao, w, "bandpass") + return taps + +# ---------------------------------------------------------------- + +def stopband_atten_to_dev (atten_db): + """Convert a stopband attenuation in dB to an absolute value""" + return 10**(-atten_db/20) + +def passband_ripple_to_dev (ripple_db): + """Convert passband ripple spec expressed in dB to an absolute value""" + return (10**(ripple_db/20)-1)/(10**(ripple_db/20)+1) + +# ---------------------------------------------------------------- + +def remezord (fcuts, mags, devs, fsamp = 2): + ''' + FIR order estimator (lowpass, highpass, bandpass, mulitiband). + + (n, fo, ao, w) = remezord (f, a, dev) + (n, fo, ao, w) = remezord (f, a, dev, fs) + + (n, fo, ao, w) = remezord (f, a, dev) finds the approximate order, + normalized frequency band edges, frequency band amplitudes, and + weights that meet input specifications f, a, and dev, to use with + the remez command. + + * f is a sequence of frequency band edges (between 0 and Fs/2, where + Fs is the sampling frequency), and a is a sequence specifying the + desired amplitude on the bands defined by f. The length of f is + twice the length of a, minus 2. The desired function is + piecewise constant. + + * dev is a sequence the same size as a that specifies the maximum + allowable deviation or ripples between the frequency response + and the desired amplitude of the output filter, for each band. + + Use remez with the resulting order n, frequency sequence fo, + amplitude response sequence ao, and weights w to design the filter b + which approximately meets the specifications given by remezord + input parameters f, a, and dev: + + b = remez (n, fo, ao, w) + + (n, fo, ao, w) = remezord (f, a, dev, Fs) specifies a sampling frequency Fs. + + Fs defaults to 2 Hz, implying a Nyquist frequency of 1 Hz. You can + therefore specify band edges scaled to a particular applications + sampling frequency. + + In some cases remezord underestimates the order n. If the filter + does not meet the specifications, try a higher order such as n+1 + or n+2. + ''' + # get local copies + fcuts = fcuts[:] + mags = mags[:] + devs = devs[:] + + for i in range (len (fcuts)): + fcuts[i] = float (fcuts[i]) / fsamp + + nf = len (fcuts) + nm = len (mags) + nd = len (devs) + nbands = nm + + if nm != nd: + raise ValueError, "Length of mags and devs must be equal" + + if nf != 2 * (nbands - 1): + raise ValueError, "Length of f must be 2 * len (mags) - 2" + + for i in range (len (mags)): + if mags[i] != 0: # if not stopband, get relative deviation + devs[i] = devs[i] / mags[i] + + # separate the passband and stopband edges + f1 = fcuts[0::2] + f2 = fcuts[1::2] + + n = 0 + min_delta = 2 + for i in range (len (f1)): + if f2[i] - f1[i] < min_delta: + n = i + min_delta = f2[i] - f1[i] + + if nbands == 2: + # lowpass or highpass case (use formula) + l = lporder (f1[n], f2[n], devs[0], devs[1]) + else: + # bandpass or multipass case + # try different lowpasses and take the worst one that + # goes through the BP specs + l = 0 + for i in range (1, nbands-1): + l1 = lporder (f1[i-1], f2[i-1], devs[i], devs[i-1]) + l2 = lporder (f1[i], f2[i], devs[i], devs[i+1]) + l = max (l, l1, l2) + + n = int (math.ceil (l)) - 1 # need order, not length for remez + + # cook up remez compatible result + ff = [0] + fcuts + [1] + for i in range (1, len (ff) - 1): + ff[i] *= 2 + + aa = [] + for a in mags: + aa = aa + [a, a] + + max_dev = max (devs) + wts = [1] * len(devs) + for i in range (len (wts)): + wts[i] = max_dev / devs[i] + + return (n, ff, aa, wts) + +# ---------------------------------------------------------------- + +def lporder (freq1, freq2, delta_p, delta_s): + ''' + FIR lowpass filter length estimator. freq1 and freq2 are + normalized to the sampling frequency. delta_p is the passband + deviation (ripple), delta_s is the stopband deviation (ripple). + + Note, this works for high pass filters too (freq1 > freq2), but + doesnt work well if the transition is near f == 0 or f == fs/2 + + From Herrmann et al (1973), Practical design rules for optimum + finite impulse response filters. Bell System Technical J., 52, 769-99 + ''' + df = abs (freq2 - freq1) + ddp = math.log10 (delta_p) + dds = math.log10 (delta_s) + + a1 = 5.309e-3 + a2 = 7.114e-2 + a3 = -4.761e-1 + a4 = -2.66e-3 + a5 = -5.941e-1 + a6 = -4.278e-1 + + b1 = 11.01217 + b2 = 0.5124401 + + t1 = a1 * ddp * ddp + t2 = a2 * ddp + t3 = a4 * ddp * ddp + t4 = a5 * ddp + + dinf=((t1 + t2 + a3) * dds) + (t3 + t4 + a6) + ff = b1 + b2 * (ddp - dds) + n = dinf / df - ff * df + 1 + return n + + +def bporder (freq1, freq2, delta_p, delta_s): + ''' + FIR bandpass filter length estimator. freq1 and freq2 are + normalized to the sampling frequency. delta_p is the passband + deviation (ripple), delta_s is the stopband deviation (ripple). + + From Mintzer and Liu (1979) + ''' + df = abs (freq2 - freq1) + ddp = math.log10 (delta_p) + dds = math.log10 (delta_s) + + a1 = 0.01201 + a2 = 0.09664 + a3 = -0.51325 + a4 = 0.00203 + a5 = -0.57054 + a6 = -0.44314 + + t1 = a1 * ddp * ddp + t2 = a2 * ddp + t3 = a4 * ddp * ddp + t4 = a5 * ddp + + cinf = dds * (t1 + t2 + a3) + t3 + t4 + a6 + ginf = -14.6 * math.log10 (delta_p / delta_s) - 16.9 + n = cinf / df + ginf * df + 1 + return n + diff --git a/gr-filter/python/pfb.py b/gr-filter/python/pfb.py index 9c7e18e31..ddf289982 100644 --- a/gr-filter/python/pfb.py +++ b/gr-filter/python/pfb.py @@ -20,8 +20,9 @@ # Boston, MA 02110-1301, USA. # -from gnuradio import gr, optfir +from gnuradio import gr import filter_swig as filter +import optfir class channelizer_ccf(gr.hier_block2): ''' @@ -32,8 +33,8 @@ class channelizer_ccf(gr.hier_block2): ''' 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 + gr.io_signature(1, 1, gr.sizeof_gr_complex), + gr.io_signature(numchans, numchans, gr.sizeof_gr_complex)) self._nchans = numchans self._oversample_rate = oversample_rate @@ -72,3 +73,199 @@ class channelizer_ccf(gr.hier_block2): self.pfb.set_channel_map(newmap) + +class interpolator_ccf(gr.hier_block2): + ''' + Make a Polyphase Filter interpolator (complex in, complex out, floating-point taps) + + The block takes a single complex stream in and outputs a single complex + stream out. As such, it requires no extra glue to handle the input/output + streams. This block is provided to be consistent with the interface to the + other PFB block. + ''' + 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), + gr.io_signature(1, 1, gr.sizeof_gr_complex)) + + 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 = filter.pfb_interpolator_ccf(self._interp, self._taps) + + self.connect(self, self.pfb) + self.connect(self.pfb, self) + + +class decimator_ccf(gr.hier_block2): + ''' + Make a Polyphase Filter decimator (complex in, complex out, floating-point taps) + + This simplifies the interface by allowing a single input stream to connect to this block. + It will then output a stream that is the decimated output stream. + ''' + def __init__(self, decim, taps=None, channel=0, atten=100): + gr.hier_block2.__init__(self, "pfb_decimator_ccf", + gr.io_signature(1, 1, gr.sizeof_gr_complex), + gr.io_signature(1, 1, gr.sizeof_gr_complex)) + + self._decim = decim + self._channel = channel + + 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._decim, 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._decim) + self.pfb = filter.pfb_decimator_ccf(self._decim, self._taps, self._channel) + + self.connect(self, self.s2ss) + + for i in xrange(self._decim): + self.connect((self.s2ss,i), (self.pfb,i)) + + self.connect(self.pfb, self) + + +class arb_resampler_ccf(gr.hier_block2): + ''' + Convenience wrapper for the polyphase filterbank arbitrary resampler. + + The block takes a single complex stream in and outputs a single complex + stream out. As such, it requires no extra glue to handle the input/output + streams. This block is provided to be consistent with the interface to the + other PFB block. + ''' + def __init__(self, rate, taps=None, flt_size=32, atten=100): + gr.hier_block2.__init__(self, "pfb_arb_resampler_ccf", + gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature + gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature + + self._rate = rate + self._size = flt_size + + 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 + #self._taps = filter.firdes.low_pass_2(self._size, self._size, bw, tb, atten) + made = False + while not made: + try: + self._taps = optfir.low_pass(self._size, self._size, 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 = filter.pfb_arb_resampler_ccf(self._rate, self._taps, self._size) + #print "PFB has %d taps\n" % (len(self._taps),) + + self.connect(self, self.pfb) + self.connect(self.pfb, self) + + # Note -- set_taps not implemented in base class yet + def set_taps(self, taps): + self.pfb.set_taps(taps) + + def set_rate(self, rate): + self.pfb.set_rate(rate) + + +class arb_resampler_fff(gr.hier_block2): + ''' + Convenience wrapper for the polyphase filterbank arbitrary resampler. + + The block takes a single float stream in and outputs a single float + stream out. As such, it requires no extra glue to handle the input/output + streams. This block is provided to be consistent with the interface to the + other PFB block. + ''' + def __init__(self, rate, taps=None, flt_size=32, atten=100): + gr.hier_block2.__init__(self, "pfb_arb_resampler_fff", + gr.io_signature(1, 1, gr.sizeof_float), # Input signature + gr.io_signature(1, 1, gr.sizeof_float)) # Output signature + + self._rate = rate + self._size = flt_size + + 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 + #self._taps = filter.firdes.low_pass_2(self._size, self._size, bw, tb, atten) + made = False + while not made: + try: + self._taps = optfir.low_pass(self._size, self._size, 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 = filter.pfb_arb_resampler_fff(self._rate, self._taps, self._size) + #print "PFB has %d taps\n" % (len(self._taps),) + + self.connect(self, self.pfb) + self.connect(self.pfb, self) + + # Note -- set_taps not implemented in base class yet + def set_taps(self, taps): + self.pfb.set_taps(taps) + + def set_rate(self, rate): + self.pfb.set_rate(rate) diff --git a/gr-filter/python/rational_resampler.py b/gr-filter/python/rational_resampler.py new file mode 100644 index 000000000..eea12af95 --- /dev/null +++ b/gr-filter/python/rational_resampler.py @@ -0,0 +1,131 @@ +# +# Copyright 2005,2007 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, gru + +_plot = None + +def design_filter(interpolation, decimation, fractional_bw): + """ + Given the interpolation rate, decimation rate and a fractional bandwidth, + design a set of taps. + + @param interpolation: interpolation factor + @type interpolation: integer > 0 + @param decimation: decimation factor + @type decimation: integer > 0 + @param fractional_bw: fractional bandwidth in (0, 0.5) 0.4 works well. + @type fractional_bw: float + @returns: sequence of numbers + """ + + if fractional_bw >= 0.5 or fractional_bw <= 0: + raise ValueError, "Invalid fractional_bandwidth, must be in (0, 0.5)" + + beta = 5.0 + trans_width = 0.5 - fractional_bw + mid_transition_band = 0.5 - trans_width/2 + + taps = gr.firdes.low_pass(interpolation, # gain + 1, # Fs + mid_transition_band/interpolation, # trans mid point + trans_width/interpolation, # transition width + gr.firdes.WIN_KAISER, + beta # beta + ) + + return taps + + + +class _rational_resampler_base(gr.hier_block2): + """ + base class for all rational resampler variants. + """ + def __init__(self, resampler_base, + interpolation, decimation, taps=None, fractional_bw=None): + """ + Rational resampling polyphase FIR filter. + + Either taps or fractional_bw may be specified, but not both. + If neither is specified, a reasonable default, 0.4, is used as + the fractional_bw. + + @param interpolation: interpolation factor + @type interpolation: integer > 0 + @param decimation: decimation factor + @type decimation: integer > 0 + @param taps: optional filter coefficients + @type taps: sequence + @param fractional_bw: fractional bandwidth in (0, 0.5), measured at final freq (use 0.4) + @type fractional_bw: float + """ + + if not isinstance(interpolation, int) or interpolation < 1: + raise ValueError, "interpolation must be an integer >= 1" + + if not isinstance(decimation, int) or decimation < 1: + raise ValueError, "decimation must be an integer >= 1" + + if taps is None and fractional_bw is None: + fractional_bw = 0.4 + + d = gru.gcd(interpolation, decimation) + interpolation = interpolation // d + decimation = decimation // d + + if taps is None: + taps = design_filter(interpolation, decimation, fractional_bw) + + resampler = resampler_base(interpolation, decimation, taps) + gr.hier_block2.__init__(self, "rational_resampler", + gr.io_signature(1, 1, resampler.input_signature().sizeof_stream_item(0)), + gr.io_signature(1, 1, resampler.output_signature().sizeof_stream_item(0))) + + self.connect(self, resampler, self) + + +class rational_resampler_fff(_rational_resampler_base): + def __init__(self, interpolation, decimation, taps=None, fractional_bw=None): + """ + Rational resampling polyphase FIR filter with + float input, float output and float taps. + """ + _rational_resampler_base.__init__(self, gr.rational_resampler_base_fff, + interpolation, decimation, taps, fractional_bw) + +class rational_resampler_ccf(_rational_resampler_base): + def __init__(self, interpolation, decimation, taps=None, fractional_bw=None): + """ + Rational resampling polyphase FIR filter with + complex input, complex output and float taps. + """ + _rational_resampler_base.__init__(self, gr.rational_resampler_base_ccf, + interpolation, decimation, taps, fractional_bw) + +class rational_resampler_ccc(_rational_resampler_base): + def __init__(self, interpolation, decimation, taps=None, fractional_bw=None): + """ + Rational resampling polyphase FIR filter with + complex input, complex output and complex taps. + """ + _rational_resampler_base.__init__(self, gr.rational_resampler_base_ccc, + interpolation, decimation, taps, fractional_bw) |