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comparison spandsp-0.0.6pre17/src/spandsp/private/v17rx.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 * private/v17rx.h - ITU V.17 modem receive part
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2003 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: v17rx.h,v 1.2.4.1 2009/12/24 16:52:30 steveu Exp $
26 */
27
28 #if !defined(_SPANDSP_PRIVATE_V17RX_H_)
29 #define _SPANDSP_PRIVATE_V17RX_H_
30
31 /* Target length for the equalizer is about 63 taps, to deal with the worst stuff
32 in V.56bis. */
33 /*! Samples before the target position in the equalizer buffer */
34 #define V17_EQUALIZER_PRE_LEN 8
35 /*! Samples after the target position in the equalizer buffer */
36 #define V17_EQUALIZER_POST_LEN 8
37
38 /*! The number of taps in the pulse shaping/bandpass filter */
39 #define V17_RX_FILTER_STEPS 27
40
41 /* We can store more trellis depth that we look back over, so that we can push out a group
42 of symbols in one go, giving greater processing efficiency, at the expense of a bit more
43 latency through the modem. */
44 /* Right now we don't take advantage of this optimisation. */
45 /*! The depth of the trellis buffer */
46 #define V17_TRELLIS_STORAGE_DEPTH 16
47 /*! How far we look back into history for trellis decisions */
48 #define V17_TRELLIS_LOOKBACK_DEPTH 16
49
50 /*!
51 V.17 modem receive side descriptor. This defines the working state for a
52 single instance of a V.17 modem receiver.
53 */
54 struct v17_rx_state_s
55 {
56 /*! \brief The bit rate of the modem. Valid values are 7200 9600, 12000 and 14400. */
57 int bit_rate;
58 /*! \brief The callback function used to put each bit received. */
59 put_bit_func_t put_bit;
60 /*! \brief A user specified opaque pointer passed to the put_but routine. */
61 void *put_bit_user_data;
62
63 /*! \brief The callback function used to report modem status changes. */
64 modem_rx_status_func_t status_handler;
65 /*! \brief A user specified opaque pointer passed to the status function. */
66 void *status_user_data;
67
68 /*! \brief A callback function which may be enabled to report every symbol's
69 constellation position. */
70 qam_report_handler_t qam_report;
71 /*! \brief A user specified opaque pointer passed to the qam_report callback
72 routine. */
73 void *qam_user_data;
74
75 /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
76 #if defined(SPANDSP_USE_FIXED_POINT)
77 int16_t rrc_filter[V17_RX_FILTER_STEPS];
78 #else
79 float rrc_filter[V17_RX_FILTER_STEPS];
80 #endif
81 /*! \brief Current offset into the RRC pulse shaping filter buffer. */
82 int rrc_filter_step;
83
84 /*! \brief The state of the differential decoder */
85 int diff;
86 /*! \brief The register for the data scrambler. */
87 uint32_t scramble_reg;
88 /*! \brief Scrambler tap */
89 //int scrambler_tap;
90
91 /*! \brief TRUE if the short training sequence is to be used. */
92 int short_train;
93 /*! \brief The section of the training data we are currently in. */
94 int training_stage;
95 /*! \brief A count of how far through the current training step we are. */
96 int training_count;
97 /*! \brief A measure of how much mismatch there is between the real constellation,
98 and the decoded symbol positions. */
99 float training_error;
100 /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
101 int16_t last_sample;
102 /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.17 signal. */
103 int signal_present;
104 /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
105 int carrier_drop_pending;
106 /*! \brief A count of the current consecutive samples below the carrier off threshold. */
107 int low_samples;
108 /*! \brief A highest magnitude sample seen. */
109 int16_t high_sample;
110
111 /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
112 uint32_t carrier_phase;
113 /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
114 int32_t carrier_phase_rate;
115 /*! \brief The carrier update rate saved for reuse when using short training. */
116 int32_t carrier_phase_rate_save;
117 #if defined(SPANDSP_USE_FIXED_POINTx)
118 /*! \brief The proportional part of the carrier tracking filter. */
119 float carrier_track_p;
120 /*! \brief The integral part of the carrier tracking filter. */
121 float carrier_track_i;
122 #else
123 /*! \brief The proportional part of the carrier tracking filter. */
124 float carrier_track_p;
125 /*! \brief The integral part of the carrier tracking filter. */
126 float carrier_track_i;
127 #endif
128
129 /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */
130 power_meter_t power;
131 /*! \brief The power meter level at which carrier on is declared. */
132 int32_t carrier_on_power;
133 /*! \brief The power meter level at which carrier off is declared. */
134 int32_t carrier_off_power;
135
136 /*! \brief Current read offset into the equalizer buffer. */
137 int eq_step;
138 /*! \brief Current write offset into the equalizer buffer. */
139 int eq_put_step;
140 /*! \brief Symbol counter to the next equalizer update. */
141 int eq_skip;
142
143 /*! \brief The current half of the baud. */
144 int baud_half;
145
146 #if defined(SPANDSP_USE_FIXED_POINTx)
147 /*! \brief The scaling factor accessed by the AGC algorithm. */
148 float agc_scaling;
149 /*! \brief The previous value of agc_scaling, needed to reuse old training. */
150 float agc_scaling_save;
151
152 /*! \brief The current delta factor for updating the equalizer coefficients. */
153 float eq_delta;
154 /*! \brief The adaptive equalizer coefficients. */
155 complexi16_t eq_coeff[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
156 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
157 complexi16_t eq_coeff_save[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
158 /*! \brief The equalizer signal buffer. */
159 complexi16_t eq_buf[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
160
161 /*! Low band edge filter for symbol sync. */
162 int32_t symbol_sync_low[2];
163 /*! High band edge filter for symbol sync. */
164 int32_t symbol_sync_high[2];
165 /*! DC filter for symbol sync. */
166 int32_t symbol_sync_dc_filter[2];
167 /*! Baud phase for symbol sync. */
168 int32_t baud_phase;
169 #else
170 /*! \brief The scaling factor accessed by the AGC algorithm. */
171 float agc_scaling;
172 /*! \brief The previous value of agc_scaling, needed to reuse old training. */
173 float agc_scaling_save;
174
175 /*! \brief The current delta factor for updating the equalizer coefficients. */
176 float eq_delta;
177 /*! \brief The adaptive equalizer coefficients. */
178 complexf_t eq_coeff[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
179 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
180 complexf_t eq_coeff_save[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
181 /*! \brief The equalizer signal buffer. */
182 complexf_t eq_buf[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
183
184 /*! Low band edge filter for symbol sync. */
185 float symbol_sync_low[2];
186 /*! High band edge filter for symbol sync. */
187 float symbol_sync_high[2];
188 /*! DC filter for symbol sync. */
189 float symbol_sync_dc_filter[2];
190 /*! Baud phase for symbol sync. */
191 float baud_phase;
192 #endif
193
194 /*! \brief The total symbol timing correction since the carrier came up.
195 This is only for performance analysis purposes. */
196 int total_baud_timing_correction;
197
198 /*! \brief Starting phase angles for the coarse carrier aquisition step. */
199 int32_t start_angles[2];
200 /*! \brief History list of phase angles for the coarse carrier aquisition step. */
201 int32_t angles[16];
202 /*! \brief A pointer to the current constellation. */
203 #if defined(SPANDSP_USE_FIXED_POINTx)
204 const complexi16_t *constellation;
205 #else
206 const complexf_t *constellation;
207 #endif
208 /*! \brief A pointer to the current space map. There is a space map for
209 each trellis state. */
210 int space_map;
211 /*! \brief The number of bits in each symbol at the current bit rate. */
212 int bits_per_symbol;
213
214 /*! \brief Current pointer to the trellis buffers */
215 int trellis_ptr;
216 /*! \brief The trellis. */
217 int full_path_to_past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
218 /*! \brief The trellis. */
219 int past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
220 /*! \brief Euclidean distances (actually the squares of the distances)
221 from the last states of the trellis. */
222 #if defined(SPANDSP_USE_FIXED_POINTx)
223 uint32_t distances[8];
224 #else
225 float distances[8];
226 #endif
227 /*! \brief Error and flow logging control */
228 logging_state_t logging;
229 };
230
231 #endif
232 /*- End of file ------------------------------------------------------------*/

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