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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 gnuradio::get_initial_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 // The over sampling rate must be rationally related to the number of channels
53 // in that it must be N/i for i in [1,N], which gives an outputsample rate
54 // of [fs/N, fs] where fs is the input sample rate.
55 // This tests the specified input sample rate to see if it conforms to this
56 // requirement within a few significant figures.
58 double fltp = modf(numchans / oversample_rate, &intp);
60 throw std::invalid_argument("gr_pfb_channelizer: oversample rate must be N/i for i in [1, N]");
62 set_relative_rate(1.0/intp);
64 d_filters = std::vector<gr_fir_ccf*>(d_numchans);
66 // Create an FIR filter for each channel and zero out the taps
67 std::vector<float> vtaps(0, d_numchans);
68 for(unsigned int i = 0; i < d_numchans; i++) {
69 d_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);
72 // Now, actually set the filters' taps
75 // Create the FFT to handle the output de-spinning of the channels
76 d_fft = new gri_fft_complex (d_numchans, false);
78 // Although the filters change, we use this look up table
79 // to set the index of the FFT input buffer, which equivalently
80 // performs the FFT shift operation on every other turn.
81 d_rate_ratio = (int)rintf(d_numchans / d_oversample_rate);
82 d_idxlut = new int[d_numchans];
83 for(unsigned int i = 0; i < d_numchans; i++) {
84 d_idxlut[i] = d_numchans - ((i + d_rate_ratio) % d_numchans) - 1;
87 // Calculate the number of filtering rounds to do to evenly
88 // align the input vectors with the output channels
89 d_output_multiple = 1;
90 while((d_output_multiple * d_rate_ratio) % d_numchans != 0)
92 set_output_multiple(d_output_multiple);
95 gr_pfb_channelizer_ccf::~gr_pfb_channelizer_ccf ()
99 for(unsigned int i = 0; i < d_numchans; i++) {
105 gr_pfb_channelizer_ccf::set_taps (const std::vector<float> &taps)
109 unsigned int ntaps = taps.size();
110 d_taps_per_filter = (unsigned int)ceil((double)ntaps/(double)d_numchans);
112 // Create d_numchan vectors to store each channel's taps
113 d_taps.resize(d_numchans);
115 // Make a vector of the taps plus fill it out with 0's to fill
116 // each polyphase filter with exactly d_taps_per_filter
117 std::vector<float> tmp_taps;
119 while((float)(tmp_taps.size()) < d_numchans*d_taps_per_filter) {
120 tmp_taps.push_back(0.0);
123 // Partition the filter
124 for(i = 0; i < d_numchans; i++) {
125 // Each channel uses all d_taps_per_filter with 0's if not enough taps to fill out
126 d_taps[i] = std::vector<float>(d_taps_per_filter, 0);
127 for(j = 0; j < d_taps_per_filter; j++) {
128 d_taps[i][j] = tmp_taps[i + j*d_numchans]; // add taps to channels in reverse order
131 // Build a filter for each channel and add it's taps to it
132 d_filters[i]->set_taps(d_taps[i]);
135 // Set the history to ensure enough input items for each filter
136 set_history (d_taps_per_filter+1);
142 gr_pfb_channelizer_ccf::print_taps()
145 for(i = 0; i < d_numchans; i++) {
146 printf("filter[%d]: [", i);
147 for(j = 0; j < d_taps_per_filter; j++) {
148 printf(" %.4e", d_taps[i][j]);
156 gr_pfb_channelizer_ccf::general_work (int noutput_items,
157 gr_vector_int &ninput_items,
158 gr_vector_const_void_star &input_items,
159 gr_vector_void_star &output_items)
161 gr_complex *in = (gr_complex *) input_items[0];
162 gr_complex *out = (gr_complex *) output_items[0];
166 return 0; // history requirements may have changed.
169 int n=1, i=-1, j=0, last;
170 int toconsume = (int)rintf(noutput_items/d_oversample_rate);
171 while(n <= toconsume) {
173 i = (i + d_rate_ratio) % d_numchans;
176 in = (gr_complex*)input_items[j];
177 d_fft->get_inbuf()[d_idxlut[j]] = d_filters[i]->filter(&in[n]);
184 in = (gr_complex*)input_items[j];
185 d_fft->get_inbuf()[d_idxlut[j]] = d_filters[i]->filter(&in[n-1]);
190 n += (i+d_rate_ratio) >= (int)d_numchans;
192 // despin through FFT
194 memcpy(out, d_fft->get_outbuf(), d_numchans*sizeof(gr_complex));
198 consume_each(toconsume);
199 return noutput_items;