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comparison spandsp-0.0.6pre17/spandsp-sim/spandsp/line_model.h @ 4:26cd8f1ef0b1

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import spandsp-0.0.6pre17
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 15:50:58 +0200
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3:c6c5a16ce2f2 4:26cd8f1ef0b1
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * line_model.h - Model a telephone line.
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2004 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Lesser General Public License version 2.1,
14 * as published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: line_model.h,v 1.7.4.1 2009/12/19 10:16:44 steveu Exp $
26 */
27
28 /*! \file */
29
30 /*! \page line_model_page Telephone line model
31 \section line_model_page_sec_1 What does it do?
32 The telephone line modelling module provides simple modelling of one way and two
33 way telephone lines.
34
35 The path being modelled is:
36
37 - terminal
38 - | < hybrid echo (2-way models)
39 - |
40 - | < noise and filtering
41 - |
42 - | < hybrid echo (2-way models)
43 - CO
44 - |
45 - | < A-law distortion + bulk delay
46 - |
47 - CO
48 - | < hybrid echo (2-way models)
49 - |
50 - | < noise and filtering
51 - |
52 - | < hybrid echo (2-way models)
53 - terminal
54 */
55
56 #if !defined(_SPANDSP_LINE_MODEL_H_)
57 #define _SPANDSP_LINE_MODEL_H_
58
59 #define SPANDSP_EXPOSE_INTERNAL_STRUCTURES
60 #include <spandsp.h>
61
62 #define LINE_FILTER_SIZE 129
63
64 /*!
65 One way line model descriptor. This holds the complete state of
66 a line model with transmission in only one direction.
67 */
68 typedef struct
69 {
70 codec_munge_state_t *munge;
71
72 /*! The coefficients for the near end analogue section simulation filter */
73 const float *near_filter;
74 /*! The number of coefficients for the near end analogue section simulation filter */
75 int near_filter_len;
76 /*! Last transmitted samples (ring buffer, used by the line filter) */
77 float near_buf[LINE_FILTER_SIZE];
78 /*! Pointer of the last transmitted sample in buf */
79 int near_buf_ptr;
80 /*! The noise source for local analogue section of the line */
81 awgn_state_t near_noise;
82
83 /*! The bulk delay of the path, in samples */
84 int bulk_delay;
85 /*! A pointer to the current write position in the bulk delay store. */
86 int bulk_delay_ptr;
87 /*! The data store for simulating the bulk delay */
88 int16_t bulk_delay_buf[8000];
89
90 /*! The coefficients for the far end analogue section simulation filter */
91 const float *far_filter;
92 /*! The number of coefficients for the far end analogue section simulation filter */
93 int far_filter_len;
94 /*! Last transmitted samples (ring buffer, used by the line filter) */
95 float far_buf[LINE_FILTER_SIZE];
96 /*! Pointer of the last transmitted sample in buf */
97 int far_buf_ptr;
98 /*! The noise source for distant analogue section of the line */
99 awgn_state_t far_noise;
100
101 /*! The scaling factor for the local CPE hybrid echo */
102 float near_cpe_hybrid_echo;
103 /*! The scaling factor for the local CO hybrid echo */
104 float near_co_hybrid_echo;
105
106 /*! The scaling factor for the far CPE hybrid echo */
107 float far_cpe_hybrid_echo;
108 /*! The scaling factor for the far CO hybrid echo */
109 float far_co_hybrid_echo;
110 /*! DC offset impairment */
111 float dc_offset;
112
113 /*! Mains pickup impairment */
114 int mains_interference;
115 tone_gen_state_t mains_tone;
116 } one_way_line_model_state_t;
117
118 /*!
119 Two way line model descriptor. This holds the complete state of
120 a line model with transmission in both directions.
121 */
122 typedef struct
123 {
124 one_way_line_model_state_t line1;
125 one_way_line_model_state_t line2;
126 float fout1;
127 float fout2;
128 } both_ways_line_model_state_t;
129
130 #ifdef __cplusplus
131 extern "C"
132 {
133 #endif
134
135 SPAN_DECLARE_DATA extern const float *line_models[];
136
137 SPAN_DECLARE(void) both_ways_line_model(both_ways_line_model_state_t *s,
138 int16_t output1[],
139 const int16_t input1[],
140 int16_t output2[],
141 const int16_t input2[],
142 int samples);
143
144 SPAN_DECLARE(void) both_ways_line_model_set_dc(both_ways_line_model_state_t *s, float dc1, float dc2);
145
146 SPAN_DECLARE(void) both_ways_line_model_set_mains_pickup(both_ways_line_model_state_t *s, int f, float level1, float level2);
147
148 SPAN_DECLARE(both_ways_line_model_state_t *) both_ways_line_model_init(int model1,
149 float noise1,
150 int model2,
151 float noise2,
152 int codec,
153 int rbs_pattern);
154
155 SPAN_DECLARE(int) both_ways_line_model_release(both_ways_line_model_state_t *s);
156
157 SPAN_DECLARE(void) one_way_line_model(one_way_line_model_state_t *s,
158 int16_t output[],
159 const int16_t input[],
160 int samples);
161
162 SPAN_DECLARE(void) one_way_line_model_set_dc(one_way_line_model_state_t *s, float dc);
163
164 SPAN_DECLARE(void) one_way_line_model_set_mains_pickup(one_way_line_model_state_t *s, int f, float level);
165
166 SPAN_DECLARE(one_way_line_model_state_t *) one_way_line_model_init(int model, float noise, int codec, int rbs_pattern);
167
168 SPAN_DECLARE(int) one_way_line_model_release(one_way_line_model_state_t *s);
169
170 #ifdef __cplusplus
171 }
172 #endif
173
174 #endif
175 /*- End of file ------------------------------------------------------------*/

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