--- /dev/null
+/* -*- c++ -*- */
+/*
+ * 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.
+ */
+
+
+#ifndef INCLUDED_GR_PFB_DECIMATOR_CCF_H
+#define INCLUDED_GR_PFB_DECIMATOR_CCF_H
+
+#include <gr_sync_block.h>
+
+class gr_pfb_decimator_ccf;
+typedef boost::shared_ptr<gr_pfb_decimator_ccf> gr_pfb_decimator_ccf_sptr;
+gr_pfb_decimator_ccf_sptr gr_make_pfb_decimator_ccf (unsigned int decim,
+ const std::vector<float> &taps,
+ unsigned int channel=0);
+
+class gr_fir_ccf;
+class gri_fft_complex;
+
+/*!
+ * \class gr_pfb_decimator_ccf
+ * \brief Polyphase filterbank bandpass decimator with gr_complex
+ * input, gr_complex output and float taps
+ *
+ * \ingroup filter_blk
+ *
+ * This block takes in a signal stream and performs interger down-
+ * sampling (decimation) with a polyphase filterbank. The first input
+ * is the integer specifying how much to decimate by. The second
+ * input is a vector (Python list) of floating-point taps of the
+ * prototype filter. The third input specifies the channel to extract.
+ * By default, the zeroth channel is used, which is the baseband
+ * channel (first Nyquist zone).
+ *
+ * The <EM>channel</EM> parameter specifies which channel to use since
+ * this class is capable of bandpass decimation. Given a complex input
+ * stream at a sampling rate of <EM>fs</EM> and a decimation rate of
+ * <EM>decim</EM>, the input frequency domain is split into
+ * <EM>decim</EM> channels that represent the Nyquist zones. Using the
+ * polyphase filterbank, we can select any one of these channels to
+ * decimate.
+ *
+ * The output signal will be the basebanded and decimated signal from
+ * that channel. This concept is very similar to the PFB channelizer
+ * (see #gr_pfb_channelizer_ccf) where only a single channel is
+ * extracted at a time.
+ *
+ * The filter's taps should be based on the sampling rate before
+ * decimation.
+ *
+ * For example, using the GNU Radio's firdes utility to building
+ * filters, we build a low-pass filter with a sampling rate of
+ * <EM>fs</EM>, a 3-dB bandwidth of <EM>BW</EM> and a transition
+ * bandwidth of <EM>TB</EM>. We can also specify the out-of-band
+ * attenuation to use, <EM>ATT</EM>, and the filter window
+ * function (a Blackman-harris window in this case). The first input
+ * is the gain of the filter, which we specify here as unity.
+ *
+ * <B><EM>self._taps = gr.firdes.low_pass_2(1, fs, BW, TB,
+ * attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)</EM></B>
+ *
+ * The PFB decimator code takes the taps generated above and builds a
+ * set of filters. The set contains <EM>decim</EM> number of filters
+ * and each filter contains ceil(taps.size()/decim) number of taps.
+ * Each tap from the filter prototype is sequentially inserted into
+ * the next filter. When all of the input taps are used, the remaining
+ * filters in the filterbank are filled out with 0's to make sure each
+ * filter has the same number of taps.
+ *
+ * The theory behind this block can be found in Chapter 6 of
+ * the following book.
+ *
+ * <B><EM>f. harris, "Multirate Signal Processing for Communication
+ * Systems," Upper Saddle River, NJ: Prentice Hall, Inc. 2004.</EM></B>
+ */
+
+class gr_pfb_decimator_ccf : public gr_sync_block
+{
+ private:
+ /*!
+ * Build the polyphase filterbank decimator.
+ * \param decim (unsigned integer) Specifies the decimation rate to use
+ * \param taps (vector/list of floats) The prototype filter to populate the filterbank.
+ * \param channel (unsigned integer) Selects the channel to return [default=0].
+ */
+ friend gr_pfb_decimator_ccf_sptr gr_make_pfb_decimator_ccf (unsigned int decim,
+ const std::vector<float> &taps,
+ unsigned int channel);
+
+ std::vector<gr_fir_ccf*> d_filters;
+ std::vector< std::vector<float> > d_taps;
+ gri_fft_complex *d_fft;
+ unsigned int d_rate;
+ unsigned int d_chan;
+ unsigned int d_taps_per_filter;
+ bool d_updated;
+ gr_complex *d_rotator;
+
+ /*!
+ * Build the polyphase filterbank decimator.
+ * \param decim (unsigned integer) Specifies the decimation rate to use
+ * \param taps (vector/list of floats) The prototype filter to populate the filterbank.
+ * \param channel (unsigned integer) Selects the channel to return [default=0].
+ */
+ gr_pfb_decimator_ccf (unsigned int decim,
+ const std::vector<float> &taps,
+ unsigned int channel);
+
+public:
+ ~gr_pfb_decimator_ccf ();
+
+ /*!
+ * Resets the filterbank's filter taps with the new prototype filter
+ * \param taps (vector/list of floats) The prototype filter to populate the filterbank.
+ */
+ void set_taps (const std::vector<float> &taps);
+
+ /*!
+ * Print all of the filterbank taps to screen.
+ */
+ void print_taps();
+
+ //void set_channel (unsigned int channel);
+
+ int work (int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items);
+};
+
+#endif
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