3 * Copyright 2009,2010 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
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15 * GNU General Public License for more details.
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27 #include <gr_pfb_channelizer_ccf.h>
28 #include <gr_fir_ccf.h>
29 #include <gr_fir_util.h>
31 #include <gr_io_signature.h>
35 gr_pfb_channelizer_ccf_sptr gr_make_pfb_channelizer_ccf (unsigned int numchans,
36 const std::vector<float> &taps,
37 float oversample_rate)
39 return gr_pfb_channelizer_ccf_sptr (new gr_pfb_channelizer_ccf (numchans, taps,
44 gr_pfb_channelizer_ccf::gr_pfb_channelizer_ccf (unsigned int numchans,
45 const std::vector<float> &taps,
46 float oversample_rate)
47 : gr_block ("pfb_channelizer_ccf",
48 gr_make_io_signature (numchans, numchans, sizeof(gr_complex)),
49 gr_make_io_signature (1, 1, numchans*sizeof(gr_complex))),
50 d_updated (false), d_numchans(numchans), d_oversample_rate(oversample_rate)
52 d_filters = std::vector<gr_fir_ccf*>(d_numchans);
54 // Create an FIR filter for each channel and zero out the taps
55 std::vector<float> vtaps(0, d_numchans);
56 for(unsigned int i = 0; i < d_numchans; i++) {
57 d_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);
60 // Now, actually set the filters' taps
63 // Create the FFT to handle the output de-spinning of the channels
64 d_fft = new gri_fft_complex (d_numchans, false);
66 // Although the filters change, we use this look up table
67 // to set the index of the FFT input buffer, which equivalently
68 // performs the FFT shift operation on every other turn.
69 d_rate_ratio = (int)rintf(d_numchans / d_oversample_rate);
70 d_idxlut = new int[d_numchans];
71 for(int i = 0; i < d_numchans; i++) {
72 d_idxlut[i] = d_numchans - ((i + d_rate_ratio) % d_numchans) - 1;
75 // Calculate the number of filtering rounds to do to evenly
76 // align the input vectors with the output channels
77 d_output_multiple = 1;
78 while((d_output_multiple * d_rate_ratio) % d_numchans != 0)
80 set_output_multiple(d_output_multiple);
83 gr_pfb_channelizer_ccf::~gr_pfb_channelizer_ccf ()
87 for(unsigned int i = 0; i < d_numchans; i++) {
93 gr_pfb_channelizer_ccf::set_taps (const std::vector<float> &taps)
97 unsigned int ntaps = taps.size();
98 d_taps_per_filter = (unsigned int)ceil((double)ntaps/(double)d_numchans);
100 // Create d_numchan vectors to store each channel's taps
101 d_taps.resize(d_numchans);
103 // Make a vector of the taps plus fill it out with 0's to fill
104 // each polyphase filter with exactly d_taps_per_filter
105 std::vector<float> tmp_taps;
107 while((float)(tmp_taps.size()) < d_numchans*d_taps_per_filter) {
108 tmp_taps.push_back(0.0);
111 // Partition the filter
112 for(i = 0; i < d_numchans; i++) {
113 // Each channel uses all d_taps_per_filter with 0's if not enough taps to fill out
114 d_taps[i] = std::vector<float>(d_taps_per_filter, 0);
115 for(j = 0; j < d_taps_per_filter; j++) {
116 d_taps[i][j] = tmp_taps[i + j*d_numchans]; // add taps to channels in reverse order
119 // Build a filter for each channel and add it's taps to it
120 d_filters[i]->set_taps(d_taps[i]);
123 // Set the history to ensure enough input items for each filter
124 set_history (d_taps_per_filter);
130 gr_pfb_channelizer_ccf::print_taps()
133 for(i = 0; i < d_numchans; i++) {
134 printf("filter[%d]: [", i);
135 for(j = 0; j < d_taps_per_filter; j++) {
136 printf(" %.4e", d_taps[i][j]);
144 gr_pfb_channelizer_ccf::general_work (int noutput_items,
145 gr_vector_int &ninput_items,
146 gr_vector_const_void_star &input_items,
147 gr_vector_void_star &output_items)
149 gr_complex *in = (gr_complex *) input_items[0];
150 gr_complex *out = (gr_complex *) output_items[0];
154 return 0; // history requirements may have changed.
157 int n=1, i=-1, j=0, last;
158 int toconsume = (int)rintf(noutput_items/d_oversample_rate);
159 while(n <= toconsume) {
161 i = (i + d_rate_ratio) % d_numchans;
164 in = (gr_complex*)input_items[j];
165 d_fft->get_inbuf()[d_idxlut[j]] = d_filters[i]->filter(&in[n]);
172 in = (gr_complex*)input_items[j];
173 d_fft->get_inbuf()[d_idxlut[j]] = d_filters[i]->filter(&in[n-1]);
178 n += (i+d_rate_ratio) >= d_numchans;
180 // despin through FFT
182 memcpy(out, d_fft->get_outbuf(), d_numchans*sizeof(gr_complex));
186 consume_each(toconsume);
187 return noutput_items;