#!/usr/bin/env python

#

# Copyright 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.

# 

from gnuradio import gr, optfir

class pfb_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), # Input signature

                                gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature

        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 = gr.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)