CN2833787Y - Noise suppression and anti-interference device for voice signals - Google Patents
Noise suppression and anti-interference device for voice signals Download PDFInfo
- Publication number
- CN2833787Y CN2833787Y CNU2005200771439U CN200520077143U CN2833787Y CN 2833787 Y CN2833787 Y CN 2833787Y CN U2005200771439 U CNU2005200771439 U CN U2005200771439U CN 200520077143 U CN200520077143 U CN 200520077143U CN 2833787 Y CN2833787 Y CN 2833787Y
- Authority
- CN
- China
- Prior art keywords
- digital
- pin
- integrated package
- digital signal
- noise reduction
- 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.)
- Expired - Fee Related
Links
Images
Landscapes
- Noise Elimination (AREA)
Abstract
The utility model designs a noise suppression and interference resisting device for speech signals, which solves the problems that fields such as speech communication, broadcasting, live monitoring recording, etc. have big background noise interference, and the existing noise suppression equipment has poor noise suppression effect. The utility model is characterized in that the utility model is mainly composed of a digital signal processor (1), an analog and digital converter (2), a digital and analog converter (8), a memory (3) and a noise suppression control circuit, the input end of the analog and digital converter (2) is connected with an outside speech signal source containing noise, and the output end of the analog and digital converter (2) is connected with the digital signal processor (1) directly or indirectly through a corresponding logic circuit. The input end of the digital and analog converter (8) is connected with the output end of the digital signal processor (1) directly or indirectly through a corresponding logic circuit, and the output end of the digital and analog converter (8) is connected with a speech output device. The memory (3) and the noise suppression control circuit (4) are both connected with the digital signal processor (1) directly or indirectly through correspondence logic circuits. The utility model has the advantages of good noise suppression effect, simple structure, wide application, low cost, small volume, etc.
Description
Technical field
The utility model relates to a kind of speech signal processing device, is a kind of speech signal processing device that filters to isolate efficient voice signal and output from the sound signal of being polluted by noise, interference, specifically a kind of voice signal noise reduction, means for anti-jamming.
Background technology
At present, in processes such as voice communication, broadcasting, on-site monitoring recording, the diversity of settings noise in earphone or the loudspeaker is to make us very pain in the neck, distinguishes that faint signal makes one nervous meaning disorderly, feels more tired for a long time in intense noise.So how to reduce these ground unrests and interference, be the problem that user and designer paid close attention to always.These generating noise mainly are because various noises that the circuit of electronic equipments such as reception, transmission own produces and signal are caused by extraneous garbage signal interference or the like in the transmission course from the transmitting apparatus to the receiving equipment, in fields such as radio communication (as medium wave, short wave communication) and on-site monitoring recording, the interference of this ground unrest is particularly serious.
In order to reduce these interference, in the present way of communication aspects mainly still aspect the performance index of the front-end circuit that improves receiver such as radio frequency, intermediate-frequency circuit, as improve the index such as sensitivity, intermodulation, reciprocal mixing, obstruction of receiver, these measures all can only reduce the noise that the circuit of receiver own is produced, suffered pollution in by Channel Transmission process such as wired, wireless is helpless to signal, so collection of letters effect is not all had clearly raising; The monitoring recording aspect then mainly adopts measures such as highly sensitive, highly directive, antimierophonic acoustic pickup at the scene, has certain effect.
About the audio defeat technology, mainly contain dynamic noise reduction technology (DNR at present, represent device such as LM1894 etc.) and Dolby NR technology (representing device such as BA1106 etc.), they all are that (sound system of 10Hz～20KHz) is designed at the broadband, (300Hz～6KHz) almost is useless to arrowband audio bandwidth commonly used, no positive effect, and they only can reduce " rustling " white noise in the ground unrest, inoperative to other interference noise, Dolby NR also needs in advance original sound signal to be carried out pre-service, noise reduction or the like is just arranged then, so they all are not suitable for the voice communication of arrowband, fields such as on-site monitoring recording.
Summary of the invention
The purpose of this utility model is that a kind of being applicable to of design carried out effective noise reduction, antijamming capability is strong, sharpness is high, applied widely voice signal noise reduction, means for anti-jamming to the voice signal of frequency range between 300Hz～6kHz.
The technical solution of the utility model is:
A kind of voice signal noise reduction, means for anti-jamming, it is characterized in that it is mainly by digital signal processor 1, modulus, digital to analog converter 2,8, storer 3 and noise reduction control circuit 4 are formed, the input of analog to digital converter 2 connects extraneous noisy speech signal source, its output directly or by corresponding logical circuit links to each other with digital signal processor 1 indirectly, the input of digital to analog converter 8 directly link to each other with the output terminal of digital signal processor 1 or by corresponding logical circuit (as Programmable Logic Device, TTL, COMS circuit etc.) link to each other indirectly, its output connects instantaneous speech power, and storer 3 and noise reduction control circuit 4 all directly or by the respective logic circuit link to each other with digital signal processor 1 indirectly.
Described analog to digital converter 2, digital to analog converter 8 are single modulus/digital-to-analogue integrated package 9.
Described single modulus/digital-to-analogue integrated package 9 adopts AD1881 series integrated package, and digital signal corresponding processor 1 is ADSP218 * serial integrated package; 24 pin of single modulus/digital-to-analogue integrated package 9 are the audio input end that contains noise, and 36 pin are the audio output behind the noise reduction; Signal I/O end 31 pin, 34 pin that digital signal I/O end 5 pin of single modulus/digital-to-analogue integrated package 9,8 pin and digital signal processor 1 are corresponding are corresponding.
Described single modulus/digital-to-analogue integrated package 9 adopts TLV320AIC23 series integrated package, and digital signal corresponding processor 1 is TMS320VC54 * serial integrated package; 19 of TLV320AIC23 series integrated package, 20 pin are connected to the audio frequency input of noise, 9,12,10,13 pin connect muting audio frequency output, 24 connect with 81 pin of TMS320VC54 * serial integrated package and link to each other, 6 pin link to each other with 47 pin of TMS320VC54 * serial integrated package by OR circuit 6,3 pin link to each other with 42 pin of TMS320VC54 * serial integrated package, input 4 pin of TLV320AIC23 series integrated package link to each other with output 60 pin of TMS320VC54 * serial integrated package, and input 7 pin of TLV320AIC23 series integrated package link to each other with output 44 pin of TMS320VC54 * serial integrated package.
Also be connected with frequency divider 5 between digital signal output end 82 pin of described digital signal processor 1 and digital signal input end 24 pin of single modulus/digital-to-analogue integrated package 9.
Signal ports such as the address end of described storer 3, data terminal, clock end, sheet choosing end select signal port such as output terminal directly to link to each other with digital signal processor 1 corresponding address end, data terminal, output terminal of clock, sheet or to pass through corresponding logical circuit continuous indirectly.
1 of storer 3 and digital signal processor also are connected with OR circuit (perhaps being realized by Programmable Logic Device) 6,7.
The contrast accompanying drawing is further described the utility model below.
Fig. 2 is the main technical scheme that constitutes with the device of U.S. ADI company, and brief introduction is as follows:
The digital signal I/O end of described digital-to-analogue/analog to digital converter 2 and digital signal processor 1 corresponding signal I/O end directly links to each other or links to each other indirectly by other logical circuit (as Programmable Logic Device, TTL, COMS circuit etc.).
The address end of described storer 3 and data terminal are with digital signal processor 1 corresponding address end and data terminal directly links to each other or it is continuous indirectly to pass through other logical circuit (as Programmable Logic Device, TTL, COMS circuit etc.).
Fig. 3 is the main technical scheme that constitutes with the device of American TI Company, and brief introduction is as follows:
The SPI serial line interface that digital-to-analogue/analog to digital converter 2, storer 3 all adopt standard and digital signal processor 1 corresponding signal I/O end directly links to each other or links to each other indirectly by other logical circuit (as Programmable Logic Device, TTL, COMS circuit etc.).Digital-to-analogue/analog to digital converter 2, each signal wire of storer 3 is in and company's state, the control signal that goes out by 95 human hair combing wastes of digital signal processor 1 by or the current operation of door (can be 74HC832 etc., also can constitute) control by Programmable Logic Device be at digital-to-analogue/analog to digital converter 2 or storer 3.The data output end of digital-to-analogue/analog to digital converter 2, storer 3 by or logical circuit such as door deliver to digital signal processor 1, the output signal of 82 pin of digital signal processor 1 is given digital-to-analogue/analog to digital converter 2 as clock signal after handling through frequency divider (can be 74HC4040 etc., also can be made of Programmable Logic Device).
The beneficial effects of the utility model:
1, can effectively reduce " rustling " ground unrest that is impregnated in the voice signal, promptly white noise disturbs, and this kind noise is generally institutes such as device interior circuit and ambient atmosphere noise to be caused.
2, can effectively reduce and be impregnated in the voice signal " ", " rumble ", " z z z " etc. various interference noises, these noises are caused by external interference that mainly these interference sources generally include the electromagnetic radiation of lightning, electric spark, Switching Power Supply, various electric equipments, the noise that mobiles causes etc.
3, can eliminate the caused interference of uttering long and high-pitched sounds of the various fixed frequencies that are impregnated in the voice signal, have automatic search and search out these interfering frequencies, automatically the function of trap filtering.It is caused that these interference noises are generally the combination tone interference, car and boat blast of whistle of electromagnetic interference, the receiver itself of extraneous other electric equipment etc.
4, simple in structure, volume is little, and cost is low.
5, utilization scope is wide.Can be installed in be hopeful to obtain clearly to transmit in the equipment or device of sound.In household electric appliances, use the class that can significantly improve equipment.
6, noise reduction is obvious.Noise reduction can reach 13.2dB in the time of can realizing selecting the one-level decrease of noise functions by the device of Fig. 2 electrical schematic diagram design; Noise reduction can reach 26.2dB when selecting the two-stage decrease of noise functions, to the inhibition effect 〉=50dB of fixed frequency interference.Device by the design of Fig. 3 electrical schematic diagram can realize that noise reduction is provided with arbitrarily by software between 0dB～40dB.
Description of drawings
Fig. 1 is a theory diagram of the present utility model.
Fig. 2 is one of electrical schematic diagram of the present utility model.
Fig. 3 is two of an electrical schematic diagram of the present utility model.
Fig. 4 is that typical case of the present utility model uses one of synoptic diagram.
Fig. 5 is that typical case of the present utility model uses two of synoptic diagram.
Fig. 6 is the application schematic block diagram that the utility model is built in communications receiving equipment inside.
Fig. 7 is the application schematic block diagram that the utility model is placed on voice signal receiving equipment outside.
Fig. 8 is the application schematic block diagram of the utility model in occasions such as monitoring, recording.
Big square frame among Fig. 4,5 is represented voice signal noise reduction of the present utility model, means for anti-jamming, and its each connecting pin is represented the input/output port and the gauge tap that are connected.Black box among Fig. 6,7,8 is also represented voice signal noise reduction of the present utility model, means for anti-jamming.
Embodiment
Below in conjunction with drawings and Examples the utility model is further described.
Embodiment one.
As shown in Figure 2.
A kind of voice signal noise reduction, means for anti-jamming, it is mainly by digital signal processor 1 (model can be ADSP218 *), single modulus/digital-to-analogue integrated package 9 (model can be AD1881), storer 3 (model can be AT29C020) and noise reduction control circuit 4 (can adopt the switching mode circuit, as Fig. 2, shown in 3) and the peripheral circuit composition, single modulus/digital-to-analogue integrated package 9, storer 3 and noise reduction control circuit 4 all link to each other with digital signal processor 1,24 pin of single modulus/digital-to-analogue integrated package 9 are the audio input end that contains noise, its 36 pin are the audio output behind the noise reduction, promptly 24 pin are the input end of whole device, and 36 pin are the output terminal of whole device.
During concrete enforcement, but the digital signal I/O end of single modulus/digital-to-analogue integrated package 9 and digital signal processor 1 corresponding signal I/O end direct physical links to each other, also Programmable Logic Device (model can be EPM7064) can be connected between two ends and other is as TTL, digital circuits such as COMS (can adopt the common circuit of textbook), realize linking to each other indirectly, but the signal characteristic on the pin of their correspondence is constant, specifically can be digital signal I/O end 5 pin of single modulus/digital-to-analogue integrated package 9, signal I/O end 31 pin that 8 pin and digital signal processor 1 are corresponding, 34 pin are corresponding.That is to say and to set up circuit such as Programmable Logic Device, TTL, COMS between corresponding signal I/O end 31 pin of digital signal I/O end 5 pin of single modulus/digital-to-analogue integrated package 9 and digital signal processor 1 and between corresponding signal I/O end 34 pin of digital signal I/O end 8 pin of single modulus/digital-to-analogue integrated package 9 and digital signal processor 1, improve the smoothness of the maintaining secrecy of circuit, security and signal circulation to advance one.
Described single modulus/digital-to-analogue integrated package 9 also can adopt two independently digital-to-analog conversion integrated package 8 and analog to digital conversion integrated package 2 come equivalent substitute during concrete enforcement.
The output terminal of noise reduction control circuit 4 links to each other with 29 pin of digital signal processor 1, and noise reduction control circuit 4 can adopt the switching mode circuit shown in Fig. 2.
The address end of storer 3 and data terminal can directly link to each other with digital signal processor 1 corresponding address end and data terminal also can realize linking to each other of corresponding end by the round about circuit of setting up picture buffer circuit (can adopt the common circuit of textbook), Programmable Logic Device and so between corresponding I/O end, and its purpose also is the confidentiality that increases stability of data transmission and increase circuit.
The address end A0 of storer 3 during concrete connection the, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12 and digital signal processor 1 address end A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12 are corresponding, data terminal D0, the D1 of storer 3, D2, D3, D4, D5, D6, D7 are corresponding with data terminal 65,68,69,70,72,73,74,75 pin of digital signal processor 1, as shown in Figure 2.
Embodiment two.
As shown in Figure 3.
A kind of voice signal noise reduction with dual input output, means for anti-jamming, it is mainly by digital signal processor 1 (model can be TMS320VC54 *), single modulus/digital-to-analogue integrated package 9 (model can be TLV320AIC23), storer 3 (model can be AT25C128) and noise reduction control circuit 4 and peripheral circuit thereof are formed, the digital signal output pin of single modulus/digital-to-analogue integrated package 9 links to each other with digital signal processor 1 by OR circuit 6 (model can be 74HC832 or constitutes with Programmable Logic Device), storer 3 links to each other with the signal I/O pin of digital signal processor 1 by described OR circuit 6 and OR circuit 7 (model can be 74HC832 or constitutes with Programmable Logic Device), and the output of noise reduction control circuit 4 links to each other with 45 pin of digital signal processor 1.In addition, between 25 pin of output pin 82 pin of digital signal processor 1 and single modulus/digital-to-analogue integrated package 9, also be connected with frequency divider 5 (model can be 74HC4040 or constitutes with Programmable Logic Device).19 of TLV320AIC23 series integrated package, 20 pin are connected to the audio frequency input of noise, 9,12,10,13 pin connect muting audio frequency output, 24 pin link to each other with 81 pin of TMS320VC54 * serial integrated package, 6 pin link to each other with 47 pin of TMS320VC54 * serial integrated package by OR circuit 6,3 pin link to each other with 42 pin of TMS320VC54 * serial integrated package, input 4 pin of TLV320AIC23 series integrated package link to each other with output 60 pin of TMS320VC54 * serial integrated package, and input 7 pin of TLV320AIC23 series integrated package link to each other with output 44 pin of TMS320VC54 * serial integrated package.
During concrete enforcement, but between the corresponding signal I/O end of the digital signal I/O end of single modulus/digital-to-analogue integrated package 9, storer 3 and digital signal processor 1 circuit such as also adjunction FPGA (Field Programmable Gate Array) with the confidentiality (model can be EPM7064) of increase circuit.
Described single modulus/digital-to-analogue integrated package 9 also can adopt two independently digital-to-analog conversion integrated package 8 and analog to digital conversion integrated package 2 come equivalent substitute during concrete enforcement.
The concrete annexation of present embodiment can be referring to shown in Figure 3, two tunnel of single modulus/digital-to-analogue integrated package 9 contain the voice signal input pin of noise and the voice signal output pin behind four road noise reductions also see shown in Figure 3, when specifically implementing among Fig. 3 the pin of each connecting pin number also can adjust according to the requirement of program.
Principle of work of the present utility model is:
The analog voice signal that at first is mixed with noise is a digital audio and video signals (A/D) by " mould/number conversion ", digital audio and video signals is imported in the digital signal processor (DSP) 1 then, handle by moving corresponding software algorithm, as the autocorrelation computing, digital adaptation filtering etc., useful voice messaging is separated from noise, interference, after then treated digital audio and video signals being delivered to D/A (D/A) conversion, be reduced to clear clean simulated audio signal, realized digitized voice de-noising, anti-interference function.As shown in Figure 1.
Fig. 4, the 5th, typical application circuit figure of the present utility model.
Fig. 6 is that device of the present utility model is built in various voice communication receiving equipments inside, and making device upgrade is the structural representation block diagram with receiving equipment of noise reduction, anti-interference function.
Fig. 7 is the outside that device of the present utility model is placed on various voice communication receiving equipments, obtain input signal in the earphone of slave unit or the loudspeaker circuit, thereby realize having the noise reduction loudspeaker (audio amplifier) of decrease of noise functions or the structural representation block diagram of noise cancelling headphone adapter by connection loudspeaker or earphone on device of the present utility model.
Fig. 8 is that device of the present utility model is used in the structural representation block diagram that the monitoring of antinoise interference, recording etc. are carried out in noisy scene.
Claims (7)
1, a kind of voice signal noise reduction, means for anti-jamming, it is characterized in that it is mainly by digital signal processor (1), modulus, digital to analog converter (2), (8), storer (3) and noise reduction control circuit (4) are formed, the input of analog to digital converter (2) connects extraneous noisy speech signal source, its output directly or by corresponding logical circuit links to each other with digital signal processor (1) indirectly, the input of digital to analog converter (8) directly links to each other with the output terminal of digital signal processor (1) or links to each other indirectly by corresponding logical circuit, its output connects instantaneous speech power, and storer (3) and noise reduction control circuit (4) all directly or by the respective logic circuit link to each other with digital signal processor (1) indirectly.
2, voice signal noise reduction according to claim 1, anti-interference putting is characterized in that described analog to digital converter (2), digital to analog converter (8) are single modulus/digital-to-analogue integrated package (9).
3, voice signal noise reduction according to claim 2, anti-interference putting is characterized in that described single modulus/digital-to-analogue integrated package (9) adopts AD1881 series integrated package, and digital signal corresponding processor (1) is ADSP218 * serial integrated package; 24 pin of single modulus/digital-to-analogue integrated package (9) are the audio input end that contains noise, and 36 pin are the audio output behind the noise reduction; Signal I/O end 31 pin, 34 pin that digital signal I/O end 5 pin of single modulus/digital-to-analogue integrated package (9), 8 pin and digital signal processor 1 are corresponding are corresponding.
4, voice signal noise reduction according to claim 2, means for anti-jamming, it is characterized in that described single modulus/digital-to-analogue integrated package (9) adopts TLV320AIC23 series integrated package, digital signal corresponding processor (1) is TMS320VC54 * serial integrated package; 19 of TLV320AIC23 series integrated package, 20 pin are connected to the audio frequency input of noise, 9,12,10,13 pin connect muting audio frequency output, 24 pin link to each other with 81 pin of TMS320VC54 * serial integrated package, 6 pin link to each other with 47 pin of TMS320VC54 * serial integrated package by OR circuit 6,3 pin link to each other with 42 pin of TMS320VC54 * serial integrated package, input 4 pin of TLV320AIC23 series integrated package link to each other with output 60 pin of TMS320VC54 * serial integrated package, and input 7 pin of TLV320AIC23 series integrated package link to each other with output 44 pin of TMS320VC54 * serial integrated package.
5, voice signal noise reduction according to claim 4, means for anti-jamming is characterized in that also being connected with frequency divider (5) between digital signal input end 24 pin of digital signal output end 82 pin of described digital signal processor (1) and single modulus/digital-to-analogue integrated package (9).
6, voice signal noise reduction according to claim 1, means for anti-jamming, the signal ports such as address end, data terminal, clock end, sheet choosing end that it is characterized in that described storer (3) select signal port such as output terminal directly to link to each other with digital signal processor (1) corresponding address end, data terminal, output terminal of clock, sheet or to pass through corresponding logical circuit continuous indirectly.
7, voice signal noise reduction according to claim 1, means for anti-jamming is characterized in that also being connected with OR circuit (6), (7) between storer (3) and digital signal processor (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2005200771439U CN2833787Y (en) | 2005-11-07 | 2005-11-07 | Noise suppression and anti-interference device for voice signals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2005200771439U CN2833787Y (en) | 2005-11-07 | 2005-11-07 | Noise suppression and anti-interference device for voice signals |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2833787Y true CN2833787Y (en) | 2006-11-01 |
Family
ID=37198097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2005200771439U Expired - Fee Related CN2833787Y (en) | 2005-11-07 | 2005-11-07 | Noise suppression and anti-interference device for voice signals |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2833787Y (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107452395A (en) * | 2017-08-23 | 2017-12-08 | 深圳创维－Rgb电子有限公司 | A kind of voice signal echo cancelling device and television set |
| CN107785028A (en) * | 2016-08-25 | 2018-03-09 | 上海英波声学工程技术股份有限公司 | Voice de-noising method and device based on signal autocorrelation |
-
2005
- 2005-11-07 CN CNU2005200771439U patent/CN2833787Y/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107785028A (en) * | 2016-08-25 | 2018-03-09 | 上海英波声学工程技术股份有限公司 | Voice de-noising method and device based on signal autocorrelation |
| CN107785028B (en) * | 2016-08-25 | 2021-06-18 | 上海英波声学工程技术股份有限公司 | Voice noise reduction method and device based on signal autocorrelation |
| CN107452395A (en) * | 2017-08-23 | 2017-12-08 | 深圳创维－Rgb电子有限公司 | A kind of voice signal echo cancelling device and television set |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10506105B2 (en) | Adaptive filter unit for being used as an echo canceller | |
| WO1998030009A3 (en) | An ac-center clipper for noise and echo suppression in a communications system | |
| CN102158778A (en) | Method, equipment and system for reducing headset noise | |
| CN2833787Y (en) | Noise suppression and anti-interference device for voice signals | |
| CN204681595U (en) | Sonification system and apply the mobile communication equipment of described sonification system | |
| CN1367978A (en) | Adaptability to multiple hands-free communication accessories | |
| CN1870612A (en) | Video differential signal transmission and keyboard/video/mouse switch | |
| CN113992223A (en) | Built-in conversation system based on microphone array noise reduction | |
| CN1822092A (en) | Method and its device for elliminating background noise in speech input | |
| CN206237570U (en) | It is a kind of that there are two kinds of noise cancelling headphones of audio access way | |
| CN103634731A (en) | Method for adjusting loudspeaker, and electronic device | |
| CN1946101A (en) | Method and device for realizing mobile terminal audio signal self adaption | |
| CN112509594A (en) | Terminal, sound production method, storage medium and electronic device | |
| CN102097115B (en) | Audio frequency playing method and mobile terminal | |
| JP2014096732A (en) | Voice collection device, and telephone set | |
| CN1798178A (en) | Mobile communication terminal possessing loudhailer with hands-free function | |
| CN1628453A (en) | Trans mitter-receiver | |
| CN201965889U (en) | Vehicle-mounted terminal and backlight adjusting circuit thereof | |
| CN102883241B (en) | The method of onboard system and elimination interference tones thereof | |
| CN1802034B (en) | Practical sound signal pick-up device for acoustic echo cancelled system sound source | |
| CN2845331Y (en) | Telephone via power line frequency carrier | |
| CN2627761Y (en) | Computer connected master-slaver mode digital telephone system | |
| CN112866854A (en) | Method and device for triggering adjustment of fade-in and fade-out mechanism through high wind noise | |
| CN201733347U (en) | Digital transmitter/receiver | |
| CN1541500A (en) | System for generating sounds |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20061101 Termination date: 20091207 |