#!/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_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), # 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 = 0.1

            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))

        self.pfb = gr.pfb_interpolator_ccf(self._interp, self._taps)

        self.connect(self, self.pfb)

        self.connect(self.pfb, self)