filter: created polyphase_filterbank parent class to handle some initialization and setting taps of PFB blocks.

Converted pfb_channelizer_ccf over to new parent class. Passes QA.
author: Tom Rondeau <trondeau@vt.edu> 2012-05-08 22:43:48 -0400
committer: Tom Rondeau <trondeau@vt.edu> 2012-05-08 22:43:48 -0400
commit: 274bc141208ac8209c6b3342ff5ddc3755b321de (patch)
tree: aa9666a189d72fb23524a138034f0ff3d660c8c3 /gr-filter/include
parent: 4f08cb7eb6e3ac4b7315b4b78dbc7d812b6c3dd1 (diff)
2 files changed, 150 insertions, 1 deletions
diff --git a/gr-filter/include/filter/CMakeLists.txt b/gr-filter/include/filter/CMakeLists.txt
index c64178696f..0c067fcba0 100644
--- a/gr-filter/include/filter/CMakeLists.txt
+++ b/gr-filter/include/filter/CMakeLists.txt
@@ -76,10 +76,11 @@ add_custom_target(filter_generated_includes DEPENDS
 install(FILES
     api.h
     firdes.h
-    pm_remez.h
     fir_filter.h
     fir_filter_with_buffer.h
     fft_filter.h
+    pm_remez.h
+    polyphase_filterbank.h
     ${generated_includes}
     dc_blocker_cc.h
     dc_blocker_ff.h
diff --git a/gr-filter/include/filter/polyphase_filterbank.h b/gr-filter/include/filter/polyphase_filterbank.h
new file mode 100644
index 0000000000..50d0873405
--- /dev/null
+++ b/gr-filter/include/filter/polyphase_filterbank.h
@@ -0,0 +1,148 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2012 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_FILTER_POLYPHASE_FILTERBANK_H
+#define	INCLUDED_FILTER_POLYPHASE_FILTERBANK_H
+
+#include <filter/api.h>
+#include <filter/fir_filter.h>
+#include <fft/fft.h>
+
+namespace gr {
+  namespace filter {
+    namespace kernel {
+
+      /*!
+       * \class polyphase_filterbank
+       *
+       * \brief Polyphase filterbank parent class
+       *
+       * \ingroup filter_blk
+       * \ingroup pfb_blk
+       *
+       * This block takes in complex inputs and channelizes it to
+       * <EM>M</EM> channels of equal bandwidth. Each of the resulting
+       * channels is decimated to the new rate that is the input
+       * sampling rate <EM>fs</EM> divided by the number of channels,
+       * <EM>M</EM>.
+       *
+       * The PFB channelizer code takes the taps generated above and
+       * builds a set of filters. The set contains <EM>M</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.
+       *
+       * Each filter operates using the gr_fir filter classs of GNU
+       * Radio, which takes the input stream at <EM>i</EM> and
+       * performs the inner product calculation to <EM>i+(n-1)</EM>
+       * where <EM>n</EM> is the number of filter taps. To efficiently
+       * handle this in the GNU Radio structure, each filter input
+       * must come from its own input stream. So the channelizer must
+       * be provided with <EM>M</EM> streams where the input stream
+       * has been deinterleaved. This is most easily done using the
+       * gr_stream_to_streams block.
+       *
+       * The output is then produced as a vector, where index
+       * <EM>i</EM> in the vector is the next sample from the
+       * <EM>i</EM>th channel. This is most easily handled by sending
+       * the output to a gr_vector_to_streams block to handle the
+       * conversion and passing <EM>M</EM> streams out.
+       *
+       * The input and output formatting is done using a hier_block2
+       * called pfb_channelizer_ccf. This can take in a single stream
+       * and outputs <EM>M</EM> streams based on the behavior
+       * described above.
+       *
+       * The filter's taps should be based on the input sampling rate.
+       *
+       * 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>
+       *
+       * More on the theory of polyphase filterbanks can be found in
+       * the following book.
+       *
+       *    <B><EM>f. harris, "Multirate Signal Processing for
+       *       Communication Systems," Upper Saddle River, NJ:
+       *       Prentice Hall, Inc. 2004.</EM></B>
+       *
+       */
+
+      class FILTER_API polyphase_filterbank
+      {
+      protected:
+	unsigned int             d_nfilts;
+	std::vector<kernel::fir_filter_ccf*> d_filters;
+	std::vector< std::vector<float> > d_taps;
+	unsigned int             d_taps_per_filter;
+	fft::fft_complex        *d_fft;
+	
+      public:
+	/*!
+	 * Build the polyphase filterbank decimator.
+	 * \param nfilts (unsigned integer) Specifies the number of
+	 *               channels <EM>M</EM>
+	 * \param taps (vector/list of floats) The prototype filter to
+	 *             populate the filterbank.
+	 */
+	polyphase_filterbank(unsigned int nfilts,
+			     const std::vector<float> &taps);
+
+	~polyphase_filterbank();
+
+	/*!
+	 * Update the filterbank's filter taps from a 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();
+
+	/*!
+	 * Return a vector<vector<>> of the filterbank taps
+	 */
+	std::vector<std::vector<float> > taps() const;
+      };
+
+    } /* namespace kernel */
+  } /* namespace filter */
+} /* namespace gr */
+
+#endif /* INCLUDED_FILTER_POLYPHASE_FILTERBANK_H */
author	Tom Rondeau <trondeau@vt.edu>	2012-05-08 22:43:48 -0400
committer	Tom Rondeau <trondeau@vt.edu>	2012-05-08 22:43:48 -0400
commit	274bc141208ac8209c6b3342ff5ddc3755b321de (patch)
tree	aa9666a189d72fb23524a138034f0ff3d660c8c3 /gr-filter/include
parent	4f08cb7eb6e3ac4b7315b4b78dbc7d812b6c3dd1 (diff)