FreeCalypso > hg > fc-tourmaline
view src/cs/layer1/gtt_include/ctm/tonedemod.h @ 210:7e225a4cd537
ETM KPD_PWR testing: add separate pressed & released calls
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Thu, 22 Apr 2021 07:30:26 +0000 |
parents | 4e78acac3d88 |
children |
line wrap: on
line source
/* ******************************************************************************* * * COPYRIGHT (C) 2000 BY ERICSSON EUROLAB DEUTSCHLAND GmbH * 90411 NUERNBERG, GERMANY, Tel Int + 49 911 5217 100 * * The program(s) may be used and/or copied only with the * written permission from Ericsson or in accordance * with the terms and conditions stipulated in the agreement or * contract under which the program(s) have been supplied. * ******************************************************************************* * * File : tonedemod.h * Purpose : Demodulator for the Cellular Text Telephone Modem * 1-out-of-4 tones (400, 600, 800, 1000 Hz) * for the coding of each pair of two adjacent bits * * Definition of the type demod_state_t and of the * functions init_tonedemod() and tonedemod() * ******************************************************************************* */ #ifndef tonedemod_h #define tonedemod_h "$Id: $" /* ******************************************************************************* * INCLUDE FILES ******************************************************************************* */ #include "ctm_defines.h" /* ******************************************************************************* * DECLARATION OF PROTOTYPES ******************************************************************************* */ typedef struct { WORD16 buffer_tone_rx[3*SYMB_LEN]; WORD16 xcorr_t0[2*SYMB_LEN]; WORD16 xcorr_t1[2*SYMB_LEN]; WORD16 xcorr_t2[2*SYMB_LEN]; WORD16 xcorr_t3[2*SYMB_LEN]; WORD16 xcorr_wb[2*SYMB_LEN]; WORD16 lowpass[SYMB_LEN]; WORD16 waveform_t0[SYMB_LEN]; WORD16 waveform_t1[SYMB_LEN]; WORD16 waveform_t2[SYMB_LEN]; WORD16 waveform_t3[SYMB_LEN]; WORD16 diff_smooth[SYMB_LEN]; } demod_state_t; /* ----------------------------------------------------------------------- */ /* FUNCTION tonedemod() */ /* ******************** */ /* Tone Demodulator for the Cellular Text Telephone Modem */ /* using one out of four tones for coding two bits in parallel within a */ /* frame of 40 samples (5 ms). */ /* */ /* The function has to be called for every frame of 40 samples of the */ /* received tone sequence. However, in order to track a non-ideal */ /* of the transmitter's and the receiver's clock frequencies, one frame */ /* might be shorter (only 39 samples) or longer (41 samples). The */ /* of the following frame is indicated by the variable */ /* *sampling_correction, which is calculated and returned by this function.*/ /* */ /* input variables: */ /* bits_out contains the 39, 40 or 41 actual samples of the */ /* received tones; the bits are soft bits, i.e. they */ /* are in the range between -1.0 and 1.0, where the */ /* magnitude serves as reliability information */ /* num_in_samples number of valid samples in bits_out */ /* */ /* output variables: */ /* bits_out contains the two actual decoded soft bits */ /* sampling_correction is either -1, 0, or 1 and indicates whether the */ /* next frame shall contain 39, 40, or 41 samples */ /* demod_state contains all the memory of tonedemod. Must be */ /* initialized using the function init_tonedemod() */ /* ----------------------------------------------------------------------- */ void tonedemod(WORD16 *bits_out, WORD16 *rx_tone_vec, WORD16 num_in_samples, WORD16 *ptr_sampling_correction, demod_state_t *demod_state); /* ----------------------------------------------------------------------- */ /* FUNCTION init_tonedemod() */ /* ************************* */ /* Initialization of one instance of the Tone Demodulator. The argument */ /* must contain a pointer to a variable of type demod_state_t, which */ /* contains all the memory of the tone demodulator. Each instance of */ /* tonedemod must have its own variable. */ /* ----------------------------------------------------------------------- */ void init_tonedemod(demod_state_t *demod_state); #endif