CN1316130A - Muting circuit having controllable impedance means for soft muting - Google Patents
Muting circuit having controllable impedance means for soft muting Download PDFInfo
- Publication number
- CN1316130A CN1316130A CN 00801215 CN00801215A CN1316130A CN 1316130 A CN1316130 A CN 1316130A CN 00801215 CN00801215 CN 00801215 CN 00801215 A CN00801215 A CN 00801215A CN 1316130 A CN1316130 A CN 1316130A
- Authority
- CN
- China
- Prior art keywords
- circuit
- noise suppression
- time constant
- suppression circuit
- muting
- 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
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
- H03G3/345—Muting during a short period of time when noise pulses are detected, i.e. blanking
Abstract
A muting circuit for application in aN anti-distortion circuit or a receiver, such as a radio receiver comprises controllable impedance means for enabling passage of a signal by controlling the impedance between an input and an output in dependence on a muting control signal on a muting control terminal of the circuit. This solution provides for soft and improved muting without a distortion, which is self inflicted by the mute interruption.
Description
The present invention relates to contain the noise suppression circuit of controllable passage means, it has an input, an output and a muting control terminal, and feasible signal path from audio input end to output depends on the muting control signal on the muting control terminal.
The invention still further relates to a kind of anti-distortion circuit and/or a kind of receiver, for example with the radio receiver of above-mentioned noise suppression circuit.These circuit are added in the radio receiving equipment usually, for example receive in the receiving equipment in the automobile of AM, SW, LW.
Can understand this noise suppression circuit from WO 97/20387, this circuit has an audio input end, an audio output and a muting control terminal.Known noise suppression circuit comprises controllable passage means, is provided with a pair of switchable inverse parallel transistor that is included in the differential amplifier, and two transistor can switch with the muting control signal on the muting control terminal.By switching this to transistor, noise suppression circuit can make closed-circuit working or not work.Particularly, in the time interval by the muting control signal indication, noise suppression circuit can controllably interrupt the audio signal path from audio input end to audio output.Owing to should utilize the conductive characteristic of cosine shape to transistorized switching, make by the edge rounding of the audio output signal of squelch break.
The shortcoming of known noise suppression circuit is, switching itself can produce the variation rapidly of obviously high parasitic homophonic and interrupted audio frequency signal amplitude, particularly at those interrupted audio output signal edges around zero place.
Therefore, the purpose of this invention is to provide a kind of noise suppression circuit, during detecting interference, itself can not cause distortion when signal interruption.
For achieving the above object, noise suppression circuit of the present invention is characterised in that its controllable passage means comprises the controllable impedance device, comes the impedance between control input end and the output and makes closed-circuit working according to muting control signal.
The advantage of noise suppression circuit of the present invention is, during the noise elimination or blanking interval of output signal, this impedance Control can provide gentle noise suppressed, and the distortion or the partials that self cause can not occur, particularly in the edge in signal interruption noise elimination cycle.Later squelch control, promptly control to zero or control to the steady state value that noise elimination begins to locate discontinuous signal at interval, can occupy the major part even the entire portion at described interval, the feasible any unexpected variation that can effectively avoid whole interim by impedance Control.So just can reduce to detect the interior distortion that self causes of whole noise elimination cycle of interference.
Additional advantage is, noise suppression circuit of the present invention is not only simple but also high performance/cost ratio is provided, and changes for big signal, has improved the letter/ratio of making an uproar, and it has only several decibels.
An embodiment of noise suppression circuit of the present invention is characterised in that this noise suppression circuit comprises a time constant network, is connected on the audio output of controllable impedance device.
This time constant network has advantageously provided the possibility that influences the discontinuous signal situation in whole noise elimination blanking interval.
Advantageously, in another embodiment of the present invention, time constant network is RC, LC or similar analog network.Its time constant can be regulated with the need, but preferably in another embodiment, the time constant of time constant network approximates half by the signal interruption phase of muting control signal indication greatly.This is splendid, compares its signal to noise ratio (SINAD) with existing noise suppression circuit and has improved about 1.8-2.2 decibel.In a specific embodiment, the time constant scope of time constant network is preferably the 100-200 microsecond between 0 and 500 microseconds.Preferable is that SINAD and signal magnitude are irrelevant, and be also irrelevant with the repetition rate of blanking pulse.
In the another embodiment of noise suppression circuit of the present invention, be provided with an anti-splatter filter, it is received on the output of controllable impedance device.Preferably as the low channel filter configuration, making it can not reserved high-frequency component or noise for this anti-splatter filter.
Further specify noise suppressed/anti-distortion circuit of the present invention and additional advantage thereof below in conjunction with accompanying drawing.Similar elements is used identical label among the figure.
Fig. 1 illustrates possible embodiment of noise suppression circuit of the present invention;
Fig. 2 illustrates the possible effect of the noise suppression circuit of application drawing 1.
Fig. 1 illustrates a kind of noise suppression circuit 1, and it is included in the anti-distortion circuit 2, and it can be the part of receiver (for example radio receiver).This receiver obtains radio or data-signal from the signal of the terminal IN reception of circuit 2.Except the audio signal of wanting, the signal on the terminal IN also has interference signal.For example in the radio receiver of automobile, this interference or distortion are to be caused by the electrical Interference from electronic device, windproof slide plate, spark plug etc. on the plate for example.Noise suppression circuit 1 can be used to suppress noise or makes audio input signal blanking during distortion or interference are arranged.
Shown anti-distortion circuit 2 comprises a disturbance detection circuit 3, and it is connected with terminal IN.An impulse circuit 4 is linked disturbance detection circuit 3, in order to have under the situation of a pulse on the control terminal 5 at noise suppression circuit 1 detecting in each cycle of interference, produces a muting control signal.Interference signal in the audio signal on the terminal IN can detect with any proper device.Also be provided with delay circuit 6 in the noise suppression circuit 1, it is connected between the audio input end 7 of terminal IN and circuit 1.In an illustrated embodiment, also be provided with an anti-splatter filter 8, it is connected between the audio output 9 and terminal OUT of circuit 1.Delay circuit 6 provides a time delay between its input and output, retardation equals the required time of disturbance detection circuit 3.Impulse circuit 4 worked to audio input signal in the suitable moment that detects after disturbing.
Fig. 2 illustrates an example of noise suppression circuit possibility role, expresses the audio frequency signal amplitude variation at any time on the audio input end 7.In the cycle shown in the I, circuit 3 detects and disturbs.The beginning that begins indicating pulse on the control terminal 5 of cycle I, noise suppression circuit 1 is arranged to make the path of the distortion audio signal of audio input end 7 to the audio output 9 owing to control group is controlled, specifically, be subjected to the time dependent control of impedance.So during the interference period I, the situation of audio signal can be affected.Possible situation is shown in a, b, c among the figure.Usually, the audio frequency signal amplitude of cycle I end must be got back to certain terminal amplitude gentlely, and it can be zero or certain other value.In order to reach specific situation, noise suppression circuit 1 will comprise a time constant network 10, and this network is linked on the audio output 9 of noise suppression circuit 1 of controllable impedance.For concrete Fig. 2, show simple RC circuit 10, it has a capacitor C and a resistance R in parallel.Suitably choose the value of electric capacity and resistance, can during the I of the interval of the audio signal on the output 9, obtain desirable first order situation.Certainly, other types or more senior network can provide other situations.These networks can comprise the LC network, and perhaps can be has for example network of value simulation such as computer, circulator or that regulate.The time constant scope of time constant network between 0 and 500 microseconds, 100-200 microsecond preferably.
As an example, can realize the impedance Control of noise suppression circuit 1 with the controllable impedance with differential input end 7 (or electricity is led) amplifier, and additional terminals 11 is linked output 9.This amplifier can be a current controlled amplifier, so, can apply Control current with impulse circuit 4 by muting control terminal 5.
If the time constant of time constant network 10 approximate audio signal interrupt cycle I during half, then can actual realize having the optimum signal-noise ratio value.In the environment of many potential interference sources is arranged, can add anti-splatter filter 8.This filter can be used as the simple low pass filter configuration.
It should be noted that except described voice applications the present invention also can be used for many other aspects, also is applicable to various signals.Application on the audio frequency only is an example.
Claims (10)
1. noise suppression circuit, comprise a controllable passage means, it has an input, an output and a muting control terminal, feasible path from input to audio output depends on the muting control signal on the muting control terminal, it is characterized in that, described controllable passage means comprises the controllable impedance device, is used for coming the impedance between control input end and the output and making closed-circuit working according to muting control signal.
2. noise suppression circuit as claimed in claim 1 is characterized in that, this circuit comprises a time constant network, and it is received on the output of controllable impedance device.
3. noise suppression circuit as claimed in claim 2 is characterized in that, described time constant network is RC, LC or similar analog network.
4. as claim 2 or 3 described noise suppression circuits, it is characterized in that the time constant of described time constant network is adjustable.
5. as the described noise suppression circuit of one of claim 2-4, it is characterized in that the time constant of described time constant network approximates half by the signal interruption phase of muting control signal indication.
6. as the described noise suppression circuit of one of claim 2-5, it is characterized in that the time constant scope of described time constant network is preferably the 100-200 microsecond between 0 and 500 microseconds.
7. as the described noise suppression circuit of one of claim 1-6, it is characterized in that this circuit also is provided with anti-splatter filter, it receives the output of controllable impedance device.
8. noise suppression circuit as claimed in claim 7 is characterized in that described anti-splatter filter is as low pass filter arrangement.
9. an anti-distortion circuit is characterized in that, this circuit is provided with wants the described noise suppression circuit of one of claim 1-8.
10. receiver, for example radio receiver is characterized in that, this receiver is provided with one of described anti-distortion circuit of claim 9 or claim 1-8 described noise suppression circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP99202079.2 | 1999-06-28 | ||
| EP99202079 | 1999-06-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1316130A true CN1316130A (en) | 2001-10-03 |
| CN1196256C CN1196256C (en) | 2005-04-06 |
Family
ID=8240371
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 00801215 Expired - Fee Related CN1196256C (en) | 1999-06-28 | 2000-06-26 | Muting circuit having controllable impedance means for soft muting |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP1110311A1 (en) |
| JP (1) | JP2003503869A (en) |
| CN (1) | CN1196256C (en) |
| WO (1) | WO2001001567A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102035571A (en) * | 2009-10-03 | 2011-04-27 | 瑞昱半导体股份有限公司 | Signal transceiving circuit and noise reduction circuit |
| CN101529850B (en) * | 2006-08-04 | 2012-04-18 | Jps通讯公司 | Method and device for providing session initiation protocol for squelch break signaling device |
| CN105577134A (en) * | 2014-10-09 | 2016-05-11 | 瑞昱半导体股份有限公司 | Transmission line driver circuit for adaptively correcting impedance matching |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4060764A (en) * | 1976-03-25 | 1977-11-29 | Motorola, Inc. | Transceiver audio system |
| US4466129A (en) * | 1982-05-06 | 1984-08-14 | Motorola, Inc. | Noise reducing circuitry for single sideband receivers |
| DE19630395C1 (en) * | 1996-07-26 | 1997-10-02 | Sgs Thomson Microelectronics | Electrical mute control circuit for audio signal |
-
2000
- 2000-06-26 JP JP2001506131A patent/JP2003503869A/en not_active Withdrawn
- 2000-06-26 EP EP00954421A patent/EP1110311A1/en not_active Withdrawn
- 2000-06-26 CN CN 00801215 patent/CN1196256C/en not_active Expired - Fee Related
- 2000-06-26 WO PCT/EP2000/005914 patent/WO2001001567A1/en not_active Application Discontinuation
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101529850B (en) * | 2006-08-04 | 2012-04-18 | Jps通讯公司 | Method and device for providing session initiation protocol for squelch break signaling device |
| CN102035571A (en) * | 2009-10-03 | 2011-04-27 | 瑞昱半导体股份有限公司 | Signal transceiving circuit and noise reduction circuit |
| CN102035571B (en) * | 2009-10-03 | 2014-01-08 | 瑞昱半导体股份有限公司 | Signal transceiving circuit and noise reduction circuit |
| CN105577134A (en) * | 2014-10-09 | 2016-05-11 | 瑞昱半导体股份有限公司 | Transmission line driver circuit for adaptively correcting impedance matching |
| CN105577134B (en) * | 2014-10-09 | 2019-05-07 | 瑞昱半导体股份有限公司 | Transmission line drive circuit for adaptive correction impedance matching |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1110311A1 (en) | 2001-06-27 |
| CN1196256C (en) | 2005-04-06 |
| WO2001001567A1 (en) | 2001-01-04 |
| JP2003503869A (en) | 2003-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR980007114A (en) | Dual mode cellular phone system | |
| US8755544B2 (en) | Earphone power amplifier, working method, and mobile terminal equipment | |
| EP1788712A2 (en) | Radio receiver | |
| JPH01162020A (en) | Fm radio receiver | |
| KR101568301B1 (en) | Method and apparatus for improving audio channel cross talk in portable terminal | |
| JPH077464A (en) | Diversity receiver | |
| CN101499783A (en) | Gain automatic regulating circuit and electronic product using the same | |
| US4654885A (en) | Mobile radio range extender with saw filter | |
| CN1196256C (en) | Muting circuit having controllable impedance means for soft muting | |
| US4525870A (en) | Automotive radio receiver with radio frequency interference elimination circuit | |
| US4584714A (en) | Automotive radio receiver with radio frequency interference elimination circuit | |
| US4479251A (en) | Noise blanker | |
| EP1881602B1 (en) | Method and circuit for audio output muting | |
| US20020141519A1 (en) | Device and method for detecting and suppressing noise | |
| US7457593B2 (en) | Attenuator system | |
| CN201699848U (en) | In tegrated 22kHz envelope detection and frequency-band switching circuit | |
| DE3127278C1 (en) | NF amplifier for a television set | |
| CN112202409A (en) | Low noise amplification module, receiver and signal processing method | |
| JPH08322143A (en) | Power supply for communication unit with fast transient noise suppressing function | |
| CN101895707A (en) | Integrated 22KHz envelope detection and frequency band switching circuit | |
| CN217216876U (en) | Wireless microphone receiver with low-cost adjustable filter circuit | |
| CN101052111A (en) | Stereo playing system for mobile TV | |
| CN215345041U (en) | Anti-jamming circuit and electronic equipment | |
| JP3479369B2 (en) | Receiver with noise removal function | |
| WO2007066528A1 (en) | Reception sensitivity detection device and reception device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |