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Diffstat (limited to 'gr-atsc/src/lib/GrAtscBitTimingLoop2.cc')
| -rw-r--r-- | gr-atsc/src/lib/GrAtscBitTimingLoop2.cc | 173 |
1 files changed, 0 insertions, 173 deletions
diff --git a/gr-atsc/src/lib/GrAtscBitTimingLoop2.cc b/gr-atsc/src/lib/GrAtscBitTimingLoop2.cc deleted file mode 100644 index c741a5bb20..0000000000 --- a/gr-atsc/src/lib/GrAtscBitTimingLoop2.cc +++ /dev/null @@ -1,173 +0,0 @@ -/* -*- c++ -*- */ -/* - * Copyright 2002 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. - */ - -#include <GrAtscBitTimingLoop2.h> -#include <algorithm> -#include <atsc_consts.h> -#include <stdio.h> -#include <assert.h> - - -static const int DEC = 2; // nominal decimation factor - -static const unsigned AVG_WINDOW_LEN = 256; -static const float TIMING_RATE_CONST = 1e-5; // FIXME document interaction with AGC - - -GrAtscBitTimingLoop2::GrAtscBitTimingLoop2 () - : VrDecimatingSigProc<float,float> (1, DEC), - next_input(0), dc (0.0002), mu (0.0), last_right(0), use_right_p (true) -{ - history = 100; // spare input samples in case we need them. - -#ifdef _BT_DIAG_OUTPUT_ - fp_loop = fopen ("loop.out", "w"); - if (fp_loop == 0){ - perror ("loop.out"); - exit (1); - } - - fp_ps = fopen ("ps.out", "w"); - if (fp_ps == 0){ - perror ("ps.out"); - exit (1); - } -#endif - -} - -// -// We are nominally a 2x decimator, but our actual rate varies slightly -// depending on the difference between the transmitter and receiver -// sampling clocks. Hence, we need to compute our input ranges -// explictly. - -int -GrAtscBitTimingLoop2::forecast(VrSampleRange output, - VrSampleRange inputs[]) { - /* dec:1 ratio with history */ - for(unsigned int i=0;i<numberInputs;i++) { - inputs[i].index=next_input; - inputs[i].size=output.size*decimation + history-1; - } - return 0; -} - -inline float -GrAtscBitTimingLoop2::filter_error (float e) -{ - return e; // identity function -} - -int -GrAtscBitTimingLoop2::work (VrSampleRange output, void *ao[], - VrSampleRange inputs[], void *ai[]) -{ - iType *in = ((iType **)ai)[0]; - oType *out = ((oType **)ao)[0]; - - // Force in-order computation of output stream. - // This is required because of our slightly variable decimation factor - sync (output.index); - - - // We are tasked with producing output.size output samples. - // We will consume approximately 2 * output.size input samples. - - - unsigned int ii = 0; // input index - unsigned int k; // output index - - // We look at a window of 3 samples that we call left (oldest), - // middle, right (newest). Each time through the loop, the previous - // right becomes the new left, and the new samples are middle and - // right. - // - // The basic game plan is to drive the average difference between - // right and left to zero. Given that all transitions are - // equiprobable (the data is white) and that the composite matched - // filter is symmetric (raised cosine) it turns out that in the - // average, if we drive that difference to zero, (implying that the - // average slope at the middle point is zero), we'll be sampling - // middle at the maximum or minimum point in the pulse. - - iType left; - iType middle; - iType right = last_right; - - for (k = 0; k < output.size; k++){ - - left = right; - - iType middle_raw = produce_sample (in, ii); - iType middle_dc = dc.filter (middle_raw); - middle = middle_raw - middle_dc; - - iType right_raw = produce_sample (in, ii); - iType right_dc = dc.filter (right_raw); - right = right_raw - right_dc; - - if (use_right_p) // produce our output - out[k] = right; - else - out[k] = middle; - } - -#ifdef _BT_DIAG_OUTPUT_ - float iodata[8]; - iodata[0] = 0; - iodata[1] = out[k]; - iodata[2] = 0; - iodata[3] = 0; - iodata[4] = 0; - iodata[5] = mu; - iodata[6] = 0; - iodata[7] = 0; // spare - if (fwrite (iodata, sizeof (iodata), 1, fp_loop) != 1){ - perror ("fwrite: loop"); - exit (1); - } -#endif - - - last_right = right; - next_input += ii; // update next_input so forecast can get us what we need - return output.size; -} - -/*! - * Produce samples equally spaced in time that are referenced - * to the transmitter's sample clock, not ours. - * - * See pp 523-527 of "Digital Communication Receivers", Meyr, - * Moeneclaey and Fechtel, Wiley, 1998. - */ - -GrAtscBitTimingLoop2::iType -GrAtscBitTimingLoop2::produce_sample (const iType *in, unsigned int &index) -{ - iType n = intr.interpolate (&in[index], mu); - - index++; - return n; -} - |