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comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/power_meter.h @ 5:f762bf195c4b
import spandsp-0.0.3
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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| date | Fri, 25 Jun 2010 16:00:21 +0200 |
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| 4:26cd8f1ef0b1 | 5:f762bf195c4b |
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| 1 /* | |
| 2 * SpanDSP - a series of DSP components for telephony | |
| 3 * | |
| 4 * power_meter.h | |
| 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 General Public License version 2, as | |
| 14 * 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 General Public License for more details. | |
| 20 * | |
| 21 * You should have received a copy of the GNU General Public License | |
| 22 * along with this program; if not, write to the Free Software | |
| 23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
| 24 * | |
| 25 * $Id: power_meter.h,v 1.8 2006/10/24 13:45:28 steveu Exp $ | |
| 26 */ | |
| 27 | |
| 28 #if !defined(_POWER_METER_H_) | |
| 29 #define _POWER_METER_H_ | |
| 30 | |
| 31 /*! \page power_meter_page Power metering | |
| 32 | |
| 33 \section power_meter_page_sec_1 What does it do? | |
| 34 The power metering module implements a simple IIR type running power meter. The damping | |
| 35 factor of the IIR is selectable when the meter instance is created. | |
| 36 | |
| 37 Note that the definition of dBOv is quite vague in most places - is it peak since wave, | |
| 38 peak square wave, etc.? This code is based on the well defined wording in RFC3389: | |
| 39 | |
| 40 "For example, in the case of a u-law system, the reference would be a square wave with | |
| 41 values +/-8031, and this square wave represents 0dBov. This translates into 6.18dBm0". | |
| 42 | |
| 43 \section power_meter_page_sec_2 How does it work? | |
| 44 */ | |
| 45 | |
| 46 /*! | |
| 47 Power meter descriptor. This defines the working state for a | |
| 48 single instance of a power measurement device. | |
| 49 */ | |
| 50 typedef struct | |
| 51 { | |
| 52 int shift; | |
| 53 | |
| 54 int32_t reading; | |
| 55 } power_meter_t; | |
| 56 | |
| 57 #ifdef __cplusplus | |
| 58 extern "C" { | |
| 59 #endif | |
| 60 | |
| 61 /*! Initialise a power meter context. | |
| 62 \brief Initialise a power meter context. | |
| 63 \param s The power meter context. | |
| 64 \param shift The shift to be used by the IIR filter. | |
| 65 \return The power meter context. */ | |
| 66 power_meter_t *power_meter_init(power_meter_t *s, int shift); | |
| 67 | |
| 68 /*! Change the damping factor of a power meter context. | |
| 69 \brief Change the damping factor of a power meter context. | |
| 70 \param s The power meter context. | |
| 71 \param shift The new shift to be used by the IIR filter. | |
| 72 \return The power meter context. */ | |
| 73 power_meter_t *power_meter_damping(power_meter_t *s, int shift); | |
| 74 | |
| 75 /*! Update a power meter. | |
| 76 \brief Update a power meter. | |
| 77 \param s The power meter context. | |
| 78 \param amp The amplitude of the new audio sample. | |
| 79 \return The current power meter reading. */ | |
| 80 int32_t power_meter_update(power_meter_t *s, int16_t amp); | |
| 81 | |
| 82 /*! Get the current power meter reading, in dBm0. | |
| 83 \brief Get the current power meter reading, in dBm0. | |
| 84 \param s The power meter context. | |
| 85 \return The current power meter reading, in dBm0. */ | |
| 86 float power_meter_dbm0(power_meter_t *s); | |
| 87 | |
| 88 /*! Get the current power meter reading, in dBOv. | |
| 89 \brief Get the current power meter reading, in dBOv. | |
| 90 \param s The power meter context. | |
| 91 \return The current power meter reading, in dBOv. */ | |
| 92 float power_meter_dbov(power_meter_t *s); | |
| 93 | |
| 94 /*! Get the power meter reading which represents a specified power level in dBm0. | |
| 95 \brief Get the current power meter reading, in dBm0. | |
| 96 \param level A power level, in dB0m. | |
| 97 \return The equivalent power meter reading. */ | |
| 98 int32_t power_meter_level_dbm0(float level); | |
| 99 | |
| 100 /*! Get the power meter reading which represents a specified power level in dBOv. | |
| 101 \brief Get the current power meter reading, in dBOv. | |
| 102 \param level A power level, in dBOv. | |
| 103 \return The equivalent power meter reading. */ | |
| 104 int32_t power_meter_level_dbov(float level); | |
| 105 | |
| 106 #ifdef __cplusplus | |
| 107 } | |
| 108 #endif | |
| 109 | |
| 110 #endif | |
| 111 /*- End of file ------------------------------------------------------------*/ |