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Diffstat (limited to 'gr-vocoder/include/vocoder/cvsd_decode_bs.h')
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1 files changed, 0 insertions, 132 deletions
diff --git a/gr-vocoder/include/vocoder/cvsd_decode_bs.h b/gr-vocoder/include/vocoder/cvsd_decode_bs.h deleted file mode 100644 index 882e5e7ddc..0000000000 --- a/gr-vocoder/include/vocoder/cvsd_decode_bs.h +++ /dev/null @@ -1,132 +0,0 @@ -/* -*- c++ -*- */ -/* - * Copyright 2007,2011,2013 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_VOCODER_CVSD_DECODE_BS_H -#define INCLUDED_VOCODER_CVSD_DECODE_BS_H - -#include <vocoder/api.h> -#include <gnuradio/sync_interpolator.h> - -namespace gr { - namespace vocoder { - - /*! - * \brief This block performs CVSD audio decoding. Its design and - * implementation is modeled after the CVSD encoder/decoder - * specifications defined in the Bluetooth standard. - * \ingroup audio_blk - * - * \details - * CVSD is a method for encoding speech that seeks to reduce the - * bandwidth required for digital voice transmission. CVSD takes - * advantage of strong correlation between samples, quantizing the - * difference in amplitude between two consecutive samples. This - * difference requires fewer quantization levels as compared to - * other methods that quantize the actual amplitude level, - * reducing the bandwidth. CVSD employs a two level quantizer - * (one bit) and an adaptive algorithm that allows for continuous - * step size adjustment. - * - * The coder can represent low amplitude signals with accuracy - * without sacrificing performance on large amplitude signals, a - * trade off that occurs in some non-adaptive modulations. - * - * The CVSD decoder effectively provides 1-to-8 decompression. - * More specifically, for each incoming input bit, the decoder - * outputs one audio sample. If the input is a "1" bit, the - * internal reference is increased appropriately and then - * outputted as the next estimated audio sample. If the input is - * a "0" bit, the internal reference is decreased appropriately - * and then likewise outputted as the next estimated audio sample. - * Grouping 8 input bits together, the encoder essentially - * produces 8 output audio samples for everyone one input byte. - * - * This decoder requires that output audio samples are 2-byte - * short signed integers. The result bandwidth conversion, - * therefore, is 1 byte of encoded audio data to 16 output bytes - * of raw audio data. - * - * The CVSD decoder module must be post-fixed by a down-converter - * to under-sample the audio data after decoding. The Bluetooth - * standard specifically calls for a 8-to-1 decimating - * down-converter. This is required so that so that output - * sampling rate equals the original input sampling rate present - * before the encoder. In all cases, the output down-converter - * rate must be the inverse of the input up-converter rate before - * the CVSD encoder. - * - * References: - * 1. Continuously Variable Slope Delta Modulation (CVSD) A Tutorial, - * Available: http://www.eetkorea.com/ARTICLES/2003AUG/A/2003AUG29_NTEK_RFD_AN02.PDF. - * 2. Specification of The Bluetooth System - * Available: http://grouper.ieee.org/groups/802/15/Bluetooth/core_10_b.pdf. - * 3. McGarrity, S., Bluetooth Full Duplex Voice and Data Transmission. 2002. - * Bluetooth Voice Simulink� Model, Available: - * http://www.mathworks.com/company/newsletters/digest/nov01/bluetooth.html - */ - class VOCODER_API cvsd_decode_bs : virtual public sync_interpolator - { - public: - // gr::vocoder::cvsd_decode_bs::sptr - typedef boost::shared_ptr<cvsd_decode_bs> sptr; - - /*! - * \brief Constructor parameters to initialize the CVSD decoder. - * The default values are modeled after the Bluetooth standard - * and should not be changed, except by an advanced user - * - * \param min_step Minimum step size used to update the internal reference. - * Default: "10" - * \param max_step Maximum step size used to update the internal reference. - * Default: "1280" - * \param step_decay Decay factor applied to step size when there is not a run of J output 1s or 0s. - * Default: "0.9990234375" (i.e. 1-1/1024) - * \param accum_decay Decay factor applied to the internal reference during every interation of the codec. - * Default: "0.96875" (i.e. 1-1/32) - * \param K; Size of shift register; the number of output bits remembered by codec (must be <= to 32). - * Default: "32" - * \param J; Number of bits in the shift register that are equal; i.e. the size of a run of 1s, 0s. - * Default: "4" - * \param pos_accum_max Maximum integer value allowed for the internal reference. - * Default: "32767" (2^15 - 1 or MAXSHORT) - * \param neg_accum_max Minimum integer value allowed for the internal reference. - * Default: "-32767" (-2^15 + 1 or MINSHORT+1) - */ - static sptr make(short min_step=10, short max_step=1280, - double step_decay=0.9990234375, double accum_decay= 0.96875, - int K=32, int J=4, - short pos_accum_max=32767, short neg_accum_max=-32767); - - virtual short min_step() = 0; - virtual short max_step() = 0; - virtual double step_decay() = 0; - virtual double accum_decay() = 0; - virtual int K() = 0; - virtual int J() = 0; - virtual short pos_accum_max() = 0; - virtual short neg_accum_max() = 0; - }; - - } /* namespace vocoder */ -} /* namespace gr */ - -#endif /* INCLUDED_VOCODER_CVSD_DECODE_BS_H */ |