CN114265334A - Automatic simulation loop impedance matching detection method - Google Patents
Automatic simulation loop impedance matching detection method Download PDFInfo
- Publication number
- CN114265334A CN114265334A CN202010972219.3A CN202010972219A CN114265334A CN 114265334 A CN114265334 A CN 114265334A CN 202010972219 A CN202010972219 A CN 202010972219A CN 114265334 A CN114265334 A CN 114265334A
- Authority
- CN
- China
- Prior art keywords
- impedance
- signal
- automatic
- cpu
- impedance matching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 29
- 238000004088 simulation Methods 0.000 title description 9
- 238000012360 testing method Methods 0.000 claims abstract description 21
- 238000004891 communication Methods 0.000 claims abstract description 19
- 238000012545 processing Methods 0.000 claims abstract description 13
- 230000005540 biological transmission Effects 0.000 claims abstract description 10
- 230000003993 interaction Effects 0.000 claims abstract description 4
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 7
- 238000005516 engineering process Methods 0.000 claims description 6
- 230000004927 fusion Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Landscapes
- Interface Circuits In Exchanges (AREA)
- Telephonic Communication Services (AREA)
Abstract
The invention discloses an automatic analog loop impedance matching detection method, which comprises the following steps: adopting an impedance automatic matching system formed by mutual interaction of a DSP processing system based on a CPU and an SLIC chip to automatically carry out impedance matching between a subscriber loop transmission line and a signal source so as to obtain an optimal matched impedance signal; the best matched impedance value is set into the SLIC to optimize the quality of the signal transmitted to the SPC switch. The invention can reduce the manual testing intensity, reduce the testing time and improve the matching accuracy, thereby improving the communication quality, improving the tone quality level of the communication, reducing the noise and improving the communication quality and the communication success rate of the communication equipment such as a fax machine, a pos machine and the like of the data terminal.
Description
Technical Field
The invention relates to the field of communication, in particular to a method for automatically matching impedance of a telephone line by using reflected signal strength, and specifically relates to a method for automatically detecting impedance matching of an analog loop.
Background
The prior voip simulation gateway adopts a special interface chip to realize the BORSCHT function of a simulation user loop, namely, an slic interface chip of a simulation telephone is utilized; in practical engineering application, due to reasons such as a path through which a line passes, a material of the line, a thickness of the line, a length of the line, and a subscriber loop impedance of a local side switch to which the line is connected, impedance configured by a gateway is unmatched, so that voice quality is poor, noise is generated, a fax effect is poor, and modem communication is wrong.
For the condition slic, a register is used for impedance matching, so that the communication effect is improved, but because the characteristics of various lines are inconsistent, even in the same country and the same city, the impedance of the same project is not matched due to the characteristics of the lines, so that the communication effect is reduced.
In the past, parameters of a matching register are generally configured manually and tested continuously to achieve a relatively good effect, so that the processing is time-consuming and labor-consuming, and the final result is not necessarily the best; the invention is optimized aiming at the situation, and achieves better impedance matching through automatic impedance detection, thereby improving the use effect of users.
Disclosure of Invention
The invention aims to provide an automatic simulation loop impedance matching detection method, which aims to solve the problem that the time and labor are wasted when the parameters of a matching register are configured manually in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
an automatic analog loop impedance matching detection method, the automatic impedance matching method includes the following steps:
adopting an impedance automatic matching system formed by mutual interaction of a DSP processing system based on a CPU and an SLIC chip to automatically carry out impedance matching between a subscriber loop transmission line and a signal source so as to obtain an optimal matched impedance signal, wherein the DSP processing system based on the CPU comprises the CPU and the DSP which are mutually and interactively connected;
the best matched impedance value is set to the telephone interface chip of the device and the SPC exchange will receive the best signal and improve the communication quality.
Further, the impedance matching system judges the impedance matching degree in an echo detection mode, and the impedance matching method of the impedance matching system is as follows:
s1, the CPU sends an instruction to set an impedance signal value;
s2, sending DTMF signal to the user loop by DSP, and transmitting to SLIC chip by PCM data bus; judging whether the DTMF signal exists according to the output signal, if so, executing step S3, otherwise, executing step S1;
s3, the DSP processor detects the reflected DTMF signal on the PCM data bus, and when the DSP detects the reflected echo, the signal matching is carried out;
s4, detecting the amplitude of the signal after the signal is matched, and recording the amplitude of the impedance and the reflected signal by measuring the amplitude of the echo to finish one-time test;
s5, continuously reducing the impedance on the SLIC chip by using the CPU to send instructions, carrying out similar tests, repeating the steps S1-S4, carrying out DTMF signal detection, measuring the echo amplitude, and acquiring more than two groups of impedance and reflected DTMF signal data; if the detection count is completed, executing step S6, and if the count is not completed, executing step S1;
and S6, obtaining a lowest echo amplitude in a plurality of groups of test data, automatically searching the impedance with the lowest echo amplitude as the best matched impedance signal value by the CPU-based DSP processing system and the SLIC chip, and setting the best impedance signal value to finish the test and finish the automatic impedance matching work.
Furthermore, the CPU is connected to the SLIC chip through a local data bus, and the local data bus is used for transmitting a CPU control signal.
Further, the PCM data bus is a digital voice path to the CPU for transmitting voice data signals.
Furthermore, the SLIC chip adopts a chip science and technology brand SI3215 type chip, is used for providing an analog subscriber loop interface to realize the fusion of the communication device gateway and the impedance data network, and comprises a control interface, a PCM interface, a tone generator, an analog-digital and digital-analog conversion circuit, a hybrid circuit, two lines of TIP and RING, and a discrete line driving circuit formed by discrete components.
Further, the DTMF signal transmitted to the SLIC chip is decoded by the SLIC chip and then transmitted to the TIP and RING lines.
Further, a dual-port RAM is arranged between the CPU and the DSP, and the dual-port RAM is used to implement data conversion between the CPU and the DSP, where the data conversion includes voice data conversion and control data conversion.
The invention has the beneficial effects that:
the automatic simulation loop impedance matching detection method provided by the invention is used for carrying out automatic user loop impedance detection, achieving better impedance matching, reducing noise, artificial test intensity and test time, improving matching accuracy, further improving communication quality and conversation tone quality level, improving user using effect, and improving communication quality and communication success rate of communication equipment such as a fax machine and a pos machine of a data terminal.
Drawings
FIG. 1 is a schematic diagram of an automatic impedance matching application of the present invention;
FIG. 2 is a flow chart of the automatic impedance matching of the present invention;
fig. 3 is a functional block diagram of a subscriber loop interface circuit of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and are only used for explaining the present invention, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, the present invention provides a technical solution: an automatic simulation loop impedance matching detection method comprises the following steps:
adopting an impedance automatic matching system formed by mutual interaction of a DSP processing system based on a CPU and an SLIC chip to automatically carry out impedance matching between a subscriber loop transmission line and a signal source so as to obtain an optimal matched impedance signal, wherein the DSP processing system based on the CPU comprises the CPU and the DSP which are mutually and interactively connected;
the best matched impedance value is set to the telephone interface chip of the device and the SPC exchange will receive the best signal and improve the communication quality.
Specifically, the impedance automatic matching system judges the impedance matching degree in an echo detection mode, wherein the higher the echo amplitude of the echo detection mode is, the lower the impedance matching degree is, and conversely, the higher the impedance matching degree is, the lower the echo amplitude is.
The impedance matching method of the impedance automatic matching system comprises the following steps:
s1, sending an instruction to set an impedance signal value through the CPU;
s2, sending DTMF signal to the user loop by DSP, and transmitting to SLIC chip by PCM data bus; judging whether the DTMF signal exists according to the output signal, if so, executing step S3, otherwise, executing step S1;
s3, the DSP processor detects the reflected DTMF signal on the PCM data bus, and when the DSP detects the reflected echo, the signal matching is carried out; DTMF signals transmitted to the SLIC chip are decoded by the SLIC chip and then transmitted to TIP and RING lines;
s4, detecting the amplitude of the signal after the signal is matched, and recording the amplitude of the impedance and the reflected signal by measuring the amplitude of the echo to finish one-time test;
s5, continuously reducing the impedance on the SLIC chip by using the CPU to send instructions, carrying out similar tests, repeating the steps S1-S4, carrying out DTMF signal detection, measuring the echo amplitude, and acquiring more than two groups of impedance and reflected DTMF signal data; if the detection count is completed, executing step S6, and if the count is not completed, executing step S1;
and S6, obtaining a lowest echo amplitude in a plurality of groups of test data, automatically searching the impedance with the lowest echo amplitude as the best matched impedance signal value by the CPU-based DSP processing system and the SLIC chip, and setting the best impedance signal value to finish the test and finish the automatic impedance matching work.
It should be noted that the DSP processing system based on the CPU provided in this embodiment is a control system that integrates the CPU and the DSP, so as to greatly increase the sending speed of the instruction, facilitate the impedance matching system to perform automatic control, and implement automatic impedance matching.
Specifically, the CPU is connected to the SLIC chip through a local data bus, and the local data bus is used for transmitting a CPU control signal; the PCM data bus is a digital voice channel to the CPU and is used for transmitting voice data signals; the dual-port RAM is arranged between the CPU and the DSP and used for realizing data conversion between the CPU and the DSP, and the data conversion comprises voice data conversion and control data conversion.
It should be noted that the DSP provided in this embodiment adopts a 32-bit digital signal processor of ADSP21020 type or TMS320C3X type; the CPU adopts a 32-bit processor based on an MIPS4kc-RISC core and is used for buffering instructions and data to complete the control of an impedance automatic matching system, and the CPU has the support of 4K-byte I-cache, 4K-byte D-cache and MMU.
Specifically, the SLIC chip adopts a chip science and technology brand SI3215 type chip, the SLIC chip is used for providing an analog subscriber loop interface to realize the fusion of a communication device gateway and an impedance data network, and the SLIC chip comprises a control interface, a PCM interface, a tone generator, an analog-digital and digital-analog conversion circuit, a hybrid circuit, two lines of TIP and RING, and a discrete line driving circuit composed of discrete components; wherein, the SLIC chip includes but is not limited to the chip science and technology brand SI3215 type chip, other brands such as Nissan chemistry, Cree company, crystal electricity, optical epitaxy, Spanish, Sanan brand series and SLIC chips of various types are also suitable for the impedance matching method of the invention; the structure and principle of the SLIC chip are well known in the market, and the control interface, the PCM interface, the tone generator, the analog-to-digital and digital-to-analog conversion circuit, the hybrid circuit, the TIP and RING two lines, and the discrete line driving circuit formed by discrete components are conventional circuit technologies in the conventional SLIC chip, and therefore are not described herein again.
It should be noted that the DSP provided in this embodiment is an english abbreviation of a digital signal processor, and is a fast and powerful microprocessor, the DSP can perform fast mathematical operations on a digital signal stream, and calculate impedance signal values matched between a subscriber loop transmission line and a signal source through a mathematical operation matching control algorithm, the mathematical operations are impedance matching control algorithms, the mathematical operations include simple addition and subtraction and multiplication to complex filtering and signal analysis functions, such as fast fourier transform and discrete cosine transform, and the DSP is embedded in an impedance automatic matching system.
The DSP works by receiving analog signals to convert them into digital signals of 0 or 1, modifying, deleting, and enhancing the digital signals, and interpreting the digital data back to analog data or actual environment format in the SLIC system chip.
Wherein, DTMF is the abbreviation of dual-tone multifrequency English; SLIC is English abbreviation of subscriber loop interface circuit, SLIC chip is analog telephone line interface circuit chip; the CPU is an acronym of the central processing unit, and mainly comprises an arithmetic unit, a controller, a register set, an internal bus and the like.
In summary, in the impedance matching detection method provided in this embodiment, the reflected echo is detected by the DTMF signal sent by the DSP, a lowest amplitude is obtained in multiple sets of test data by measuring the amplitude of the echo, and the impedance is defined as a finally matched impedance, and is transmitted to the SLIC chip through the PCM data bus, and the signal is sent to the TIP and RING two lines through decoding of the SLIC chip, at this time, the DSP monitors the reflected DTMF signal on the PCM data bus, and if the signals are matched, detects the amplitude thereof; by continuously setting the impedance on the SLIC chip and carrying out similar tests, a group of impedance and data of the reflected DTMF signals are finally obtained, and the impedance with the lowest reflected signal amplitude is selected as the optimal matching impedance.
The automatic simulation loop impedance matching detection method provided by the invention is used for carrying out automatic user loop impedance matching, reducing the manual testing intensity, reducing the testing time and improving the matching accuracy, and the communication tone quality of the gateway is greatly improved after impedance matching, the noise is reduced, and the fax/pos reliability is improved.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. An automatic analog loop impedance matching detection method is characterized by comprising the following steps:
adopting an impedance automatic matching system formed by mutual interaction of a DSP processing system based on a CPU and an SLIC chip to automatically carry out impedance matching between a subscriber loop transmission line and a signal source so as to obtain an optimal matched impedance signal, wherein the DSP processing system based on the CPU comprises the CPU and the DSP which are mutually and interactively connected;
the test signal is transmitted to the traditional analog transmission line, because the transmission system can reflect the signal when the impedance is not matched, and the optimal impedance value of the transmission system consisting of the transmission line and the stored program controlled exchange is automatically matched and transmitted through checking the reflected signal.
2. The automatic analog loop impedance matching detection method of claim 1, characterized in that: the impedance automatic matching system judges the impedance matching degree in an echo detection mode, and the impedance matching method of the impedance automatic matching system comprises the following steps:
s1, the CPU sends an instruction to set an impedance signal value;
s2, sending DTMF signal to the user loop by DSP, and transmitting to SLIC chip by PCM data bus; judging whether the DTMF signal exists according to the output signal, if so, executing step S3, otherwise, executing step S1;
s3, the DSP processor detects the reflected DTMF signal on the PCM data bus, and when the DSP detects the reflected echo, the signal matching is carried out;
s4, detecting the amplitude of the signal after the signal is matched, and recording the amplitude of the impedance and the reflected signal by measuring the amplitude of the echo to finish one-time test;
s5, continuously adjusting the impedance on the SLIC chip by using the CPU to send instructions, carrying out similar tests, repeating the steps S1-S4, carrying out DTMF signal detection, measuring the echo amplitude, and obtaining more than two groups of impedance and reflected DTMF signal data; if the detection count is completed, executing step S6, and if the count is not completed, executing step S1;
and S6, obtaining a lowest echo amplitude in a plurality of groups of test data, automatically searching the impedance with the lowest echo amplitude as the best matched impedance signal value by the CPU-based DSP processing system and the SLIC chip, and setting the best impedance signal value to finish the test and finish the automatic impedance matching work.
3. The automatic analog loop impedance matching detection method according to claim 1 or 2, characterized in that: the strength of the reflected signal between the detection device and the transmission system is used to perform automatic matching of the impedance of the SLIC.
4. The automatic analog loop impedance matching detection method of claim 2, characterized in that: the PCM data bus is a digital voice path to the CPU for transmitting voice data signals.
5. The automatic analog loop impedance matching detection method of claim 1, characterized in that: the SLIC chip adopts a chip science and technology brand SI3215 type chip, is used for providing an analog subscriber loop interface to realize the fusion of a communication equipment gateway and an impedance data network, and comprises a control interface, a PCM interface, a tone generator, an analog-digital and digital-analog conversion circuit, a hybrid circuit, two TIP and RING lines and a discrete line driving circuit consisting of discrete elements.
6. The automatic analog loop impedance matching detection method of claim 2, characterized in that: and the DTMF signal transmitted to the SLIC chip is decoded by the SLIC chip and then transmitted to TIP and RING lines.
7. The automatic analog loop impedance matching detection method of claim 1, characterized in that: and a dual-port RAM is arranged between the CPU and the DSP and is used for realizing data conversion between the CPU and the DSP, and the data conversion comprises voice data conversion and control data conversion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010972219.3A CN114265334B (en) | 2020-09-16 | 2020-09-16 | Automatic analog loop impedance matching detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010972219.3A CN114265334B (en) | 2020-09-16 | 2020-09-16 | Automatic analog loop impedance matching detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114265334A true CN114265334A (en) | 2022-04-01 |
| CN114265334B CN114265334B (en) | 2024-04-09 |
Family
ID=80824221
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010972219.3A Active CN114265334B (en) | 2020-09-16 | 2020-09-16 | Automatic analog loop impedance matching detection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114265334B (en) |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10163889A (en) * | 1996-12-03 | 1998-06-19 | Kokusai Electric Co Ltd | Automatic impedance matching system |
| WO2000079693A1 (en) * | 1999-06-18 | 2000-12-28 | 2Wire, Inc. | Active hybrid with dynamic impedance matching against different loop conditions and related method |
| US6377681B1 (en) * | 1998-04-01 | 2002-04-23 | National Semiconductor Corporation | Signal line driving circuit with self-controlled power dissipation |
| CN1389853A (en) * | 2001-06-01 | 2003-01-08 | 华为技术有限公司 | Phonetic codec chip capable of realizing impedance matching and mixed balance |
| CN1575559A (en) * | 2001-10-24 | 2005-02-02 | 卡提纳网络公司 | Method and apparatus for transient suppression in an integrated pots/dsl line card |
| US20050195121A1 (en) * | 2004-03-05 | 2005-09-08 | Curitel Communications, Inc. | Impedance matching apparatus in a mobile communication terminal |
| CN1694422A (en) * | 2005-05-11 | 2005-11-09 | 港湾网络有限公司 | Method for testing network transmission line using time-domain signal |
| WO2006022132A1 (en) * | 2004-08-23 | 2006-03-02 | Nec Corporation | High-frequency circuit, and communication device using the same |
| CN101202566A (en) * | 2006-11-17 | 2008-06-18 | 深圳市业通达实业有限公司 | Transmit-receive common frequency power line carrier system |
| CN103151853A (en) * | 2013-04-03 | 2013-06-12 | 天津工业大学 | Wireless power transmission impedance automatic matching device |
| CN106488071A (en) * | 2015-08-26 | 2017-03-08 | 日本冲信息株式会社 | Communication equipment |
-
2020
- 2020-09-16 CN CN202010972219.3A patent/CN114265334B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10163889A (en) * | 1996-12-03 | 1998-06-19 | Kokusai Electric Co Ltd | Automatic impedance matching system |
| US6377681B1 (en) * | 1998-04-01 | 2002-04-23 | National Semiconductor Corporation | Signal line driving circuit with self-controlled power dissipation |
| WO2000079693A1 (en) * | 1999-06-18 | 2000-12-28 | 2Wire, Inc. | Active hybrid with dynamic impedance matching against different loop conditions and related method |
| CN1389853A (en) * | 2001-06-01 | 2003-01-08 | 华为技术有限公司 | Phonetic codec chip capable of realizing impedance matching and mixed balance |
| CN1575559A (en) * | 2001-10-24 | 2005-02-02 | 卡提纳网络公司 | Method and apparatus for transient suppression in an integrated pots/dsl line card |
| US20050195121A1 (en) * | 2004-03-05 | 2005-09-08 | Curitel Communications, Inc. | Impedance matching apparatus in a mobile communication terminal |
| WO2006022132A1 (en) * | 2004-08-23 | 2006-03-02 | Nec Corporation | High-frequency circuit, and communication device using the same |
| CN1694422A (en) * | 2005-05-11 | 2005-11-09 | 港湾网络有限公司 | Method for testing network transmission line using time-domain signal |
| CN101202566A (en) * | 2006-11-17 | 2008-06-18 | 深圳市业通达实业有限公司 | Transmit-receive common frequency power line carrier system |
| CN103151853A (en) * | 2013-04-03 | 2013-06-12 | 天津工业大学 | Wireless power transmission impedance automatic matching device |
| CN106488071A (en) * | 2015-08-26 | 2017-03-08 | 日本冲信息株式会社 | Communication equipment |
Non-Patent Citations (2)
| Title |
|---|
| 周胡净等: "基于Si32261的FXS接口设计与应用", 微处理机, no. 03, 15 June 2017 (2017-06-15), pages 79 - 82 * |
| 张海华;: "回波损耗测量法在高频通道故障处理中的应用", 电力信息与通信技术, vol. 11, no. 10, 15 October 2013 (2013-10-15), pages 34 - 38 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114265334B (en) | 2024-04-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1204760C (en) | Method and apparatus for early detection of DTMF signals in voice transmission over IP network | |
| CN1089513C (en) | TX preemphasis filter and TX power control based high speed two-wire modem | |
| US5875230A (en) | Interactive measurement system and method for telecommunication networks | |
| CN1260659A (en) | Telephone testing instrument | |
| CN107613147B (en) | Intelligent switching device, testing system and testing method for private telephone line | |
| CN1300498A (en) | A method and system for scaleable near-end speech cancellation for tip and ring tone signal detectors | |
| CN114265334A (en) | Automatic simulation loop impedance matching detection method | |
| US6269160B1 (en) | Communications device including an improved CPE alerting signal (CAS) detection system | |
| JPH11331429A (en) | Call-related information receiving unit | |
| US6748050B2 (en) | Method and apparatus for performing either tone analysis on a local looped-back communications path or utilizing a hybrid reflection based looped-back test to test integrity | |
| CN1780165B (en) | Echo eliminator and elimination method | |
| US6810112B1 (en) | Method and apparatus for testing an information notification service | |
| CN101621311A (en) | Echo cancellation balance using noise generator and average power detection | |
| WO2006050655A1 (en) | A voice quality testing method and testing apparatus of ip telephone | |
| KR20010065803A (en) | Method for changing timbre during conversation in portable telephone | |
| CN111405131A (en) | Method, system and storage medium for detecting far-end off-hook signal | |
| JPH11225121A (en) | Mobile communications network channel test method | |
| CN100474869C (en) | Transmission channel detecting method and calling control system | |
| SE9601951L (en) | Procedure for automatically connecting incoming signal to outgoing location in automatic answering machine where tripartite call service is subscribed | |
| JP3303524B2 (en) | Echo canceller learning method | |
| CN210780961U (en) | VoIP (Voice over Internet protocol) equipment with loop noise self-checking function and VoIP voice system | |
| KR100251828B1 (en) | Method for synchronizing between the devices measuring speech quality in the mobile telecommunication environment | |
| CN100463383C (en) | Method and apparatus for detecting phase reversal of digital signal tone | |
| de Campos Neto et al. | Performance of ITU-T G. 729 8 kb/s CS-ACELP speech codec with nonvoice narrowband signals | |
| KR20000001738A (en) | Apparatus and method for connecting 1:1 data communication in audio communication |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |