GNU Radio 3.6.4 C++ API
pfb_decimator_ccf.h
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/* -*- c++ -*- */
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/*
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* Copyright 2009,2012 Free Software Foundation, Inc.
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*
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* This file is part of GNU Radio
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*
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* GNU Radio is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* GNU Radio is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Radio; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef INCLUDED_PFB_DECIMATOR_CCF_H
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#define INCLUDED_PFB_DECIMATOR_CCF_H
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#include <
filter/api.h
>
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#include <
gr_sync_block.h
>
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namespace
gr {
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namespace
filter {
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/*!
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* \class pfb_decimator_ccf
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* \brief Polyphase filterbank bandpass decimator with gr_complex
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* input, gr_complex output and float taps
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*
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* \ingroup filter_blk
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* \ingroup pfb_blk
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*
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* This block takes in a signal stream and performs interger down-
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* sampling (decimation) with a polyphase filterbank. The first
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* input is the integer specifying how much to decimate by. The
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* second input is a vector (Python list) of floating-point taps
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* of the prototype filter. The third input specifies the channel
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* to extract. By default, the zeroth channel is used, which is
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* the baseband channel (first Nyquist zone).
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*
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* The <EM>channel</EM> parameter specifies which channel to use
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* since this class is capable of bandpass decimation. Given a
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* complex input stream at a sampling rate of <EM>fs</EM> and a
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* decimation rate of <EM>decim</EM>, the input frequency domain
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* is split into <EM>decim</EM> channels that represent the
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* Nyquist zones. Using the polyphase filterbank, we can select
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* any one of these channels to decimate.
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*
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* The output signal will be the basebanded and decimated signal
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* from that channel. This concept is very similar to the PFB
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* channelizer (see #gr_pfb_channelizer_ccf) where only a single
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* channel is extracted at a time.
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*
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* The filter's taps should be based on the sampling rate before
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* decimation.
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*
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* For example, using the GNU Radio's firdes utility to building
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* filters, we build a low-pass filter with a sampling rate of
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* <EM>fs</EM>, a 3-dB bandwidth of <EM>BW</EM> and a transition
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* bandwidth of <EM>TB</EM>. We can also specify the out-of-band
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* attenuation to use, <EM>ATT</EM>, and the filter window
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* function (a Blackman-harris window in this case). The first
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* input is the gain of the filter, which we specify here as
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* unity.
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*
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* <B><EM>self._taps = filter.firdes.low_pass_2(1, fs, BW, TB,
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* attenuation_dB=ATT, window=filter.firdes.WIN_BLACKMAN_hARRIS)</EM></B>
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*
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* The PFB decimator code takes the taps generated above and
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* builds a set of filters. The set contains <EM>decim</EM> number
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* of filters and each filter contains ceil(taps.size()/decim)
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* number of taps. Each tap from the filter prototype is
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* sequentially inserted into the next filter. When all of the
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* input taps are used, the remaining filters in the filterbank
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* are filled out with 0's to make sure each filter has the same
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* number of taps.
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*
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* The theory behind this block can be found in Chapter 6 of
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* the following book.
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*
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* <B><EM>f. harris, "Multirate Signal Processing for Communication
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* Systems," Upper Saddle River, NJ: Prentice Hall, Inc. 2004.</EM></B>
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*/
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class
FILTER_API
pfb_decimator_ccf
:
virtual
public
gr_sync_block
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{
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public
:
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// gr::filter::pfb_decimator_ccf::sptr
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typedef
boost::shared_ptr<pfb_decimator_ccf>
sptr
;
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/*!
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* Build the polyphase filterbank decimator.
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* \param decim (unsigned integer) Specifies the decimation rate to use
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* \param taps (vector/list of floats) The prototype filter to populate the filterbank.
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* \param channel (unsigned integer) Selects the channel to return [default=0].
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*/
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static
sptr
make(
unsigned
int
decim,
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const
std::vector<float> &
taps
,
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unsigned
int
channel);
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/*!
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* Resets the filterbank's filter taps with the new prototype filter
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* \param taps (vector/list of floats) The prototype filter to populate the filterbank.
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*/
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virtual
void
set_taps(
const
std::vector<float> &
taps
) = 0;
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/*!
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* Return a vector<vector<>> of the filterbank taps
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*/
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virtual
std::vector<std::vector<float> >
taps
()
const
= 0;
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/*!
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* Print all of the filterbank taps to screen.
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*/
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virtual
void
print_taps() = 0;
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//virtual void set_channel(unsigned int channel) = 0;
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};
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}
/* namespace filter */
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}
/* namespace gr */
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#endif
/* INCLUDED_PFB_DECIMATOR_CCF_H */
gnuradio
gr-filter
include
filter
pfb_decimator_ccf.h
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