CN102545785B - Noise suppression circuit and method for frequency modulator - Google Patents
Noise suppression circuit and method for frequency modulator Download PDFInfo
- Publication number
- CN102545785B CN102545785B CN201210039785.4A CN201210039785A CN102545785B CN 102545785 B CN102545785 B CN 102545785B CN 201210039785 A CN201210039785 A CN 201210039785A CN 102545785 B CN102545785 B CN 102545785B
- Authority
- CN
- China
- Prior art keywords
- resistance
- amplifier
- termination
- electric capacity
- circuit
- 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
Landscapes
- Amplifiers (AREA)
Abstract
The invention discloses a noise suppression circuit and a noise suppression method for a frequency modulator. The frequency modulator with the noise suppression circuit comprises a tuning circuit, a frequency conversion circuit, an intermediate-frequency amplification circuit, the noise suppression circuit, a detecting circuit, an audio pre-amplification circuit and an audio power amplification circuit, wherein the tuning circuit is used for selecting a signal of certain frequency; the frequency conversion circuit mixes the signal selected by the tuning circuit and a local oscillator to obtain an intermediate-frequency signal; the intermediate-frequency amplification circuit amplifies the intermediate-frequency signal obtained by the frequency conversion circuit to meet the requirements of the detecting circuit; the noise suppression circuit suppresses noise produced when the frequency-modulated signal is not received; the detecting circuit demodulates an audio signal from an audio packet, and filters a high-frequency signal; the audio pre-amplification circuit performs open loop pre-amplification on the audio signal output by the detecting circuit; and the audio power amplification circuit performs closed loop amplification on the audio signal to drive a loudspeaker. By the circuit and the method, the noise produced when the frequency-modulated signal is not received can be effectively suppressed.
Description
Technical field
The present invention relates to noise reduction techniques, particularly relate to the noise suppression circuit for frequency modulation machine and method thereof.
Background technology
Fig. 1 is the structure chart of existing frequency modulation machine, comprises tuning circuit 101, frequency changer circuit 102, intermediate frequency amplifier circuit 103, detecting circuit 104, audio frequency pre-amplification circuit 105 and audio power amplifying circuit 106.Described tuning circuit 101 is the signals in order to choose some frequencies; Described frequency changer circuit 102 carries out mixing to the tuning signal selected and local oscillator, therefrom obtains intermediate-freuqncy signal; Described intermediate frequency amplifier circuit 103 is amplified the intermediate-freuqncy signal that described frequency changer circuit 102 obtains, to such an extent as to reach the requirement of detecting circuit; Described detecting circuit 104 is audio signal from demodulation audio pack out, filtering high-frequency signal; Described audio frequency pre-amplification circuit 105 carries out open loop pre-amplification to the audio signal that detection exports; Described audio power amplifying circuit 106 carries out closed loop amplification to audio signal, to reaching promotion loud speaker.
The operation principle of existing frequency modulation machine is: the high-frequency signal that antenna receives is chosen by tuning circuit, then sent in frequency changer circuit together with wireless local oscillation frequency by input circuit and mix, frequency-selecting produces intermediate frequency, intermediate frequency only changes and carries wave frequency, audio pack winding thread originally does not change, intermediate-freuqncy signal can be amplified better by intermediate frequency amplifier circuit, intermediate-freuqncy signal after amplification demodulates audio signal and filtering high-frequency signal through detection, again after audio frequency pre-amplification and power amplification, promote loud speaker and sound.
Existing frequency modulation machine is not when intermediate frequency amplifier circuit reaches detecting circuit requirement, when namely not receiving FM signal, have high-frequency signal by described intermediate frequency amplifier circuit 103 and described detecting circuit 104, then be input to described audio frequency pre-amplification circuit 105 and described audio power amplifying circuit 106 carries out power amplification, make noise allow people be difficult to stand.In order to suppress this noise, just need to arrange noise suppression circuit.
Summary of the invention
The present invention is intended to solve the deficiencies in the prior art, provide a kind of can the noise suppression circuit of restraint speckle effectively.
Present invention also offers a kind of method of noise suppressed.
There is the frequency modulation machine of noise suppression circuit, comprise tuning circuit, frequency changer circuit, intermediate frequency amplifier circuit, noise suppression circuit, detecting circuit, audio frequency pre-amplification circuit and audio power amplifying circuit:
Described tuning circuit is the signal in order to choose some frequencies;
Described frequency changer circuit carries out mixing to the tuning signal chosen and local oscillator, therefrom obtains intermediate-freuqncy signal;
Described intermediate frequency amplifier circuit is amplified the intermediate-freuqncy signal that described frequency changer circuit obtains, to such an extent as to reach the requirement of detecting circuit;
Described noise suppression circuit suppresses the noise when not receiving FM signal;
Described detecting circuit is audio signal from demodulation audio pack out, filtering high-frequency signal;
Described audio frequency pre-amplification circuit carries out open loop pre-amplification to the audio signal that detection exports;
Described audio power amplifying circuit carries out closed loop amplification to audio signal, to reaching promotion loud speaker.
Described intermediate frequency amplifier circuit comprises the first amplifier, the second amplifier, the 3rd amplifier, the 4th amplifier, the 5th amplifier, the first electric capacity, the second electric capacity, the 3rd electric capacity, the 4th electric capacity, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, the first resistance, the second resistance and the 3rd resistance:
The signal that frequency changer circuit described in the positive termination of described first amplifier exports, negative terminal connects the first resistance to anode, and output plus terminal connects second electric capacity one end, exports negative terminal and connects first electric capacity one end;
One end of positive termination second electric capacity of described second amplifier, negative terminal connects one end of the first electric capacity, and output plus terminal connects the 4th electric capacity one end, exports negative terminal and connects the 3rd electric capacity one end;
One end of positive termination the 4th electric capacity of described 3rd amplifier, negative terminal connects one end of the 3rd electric capacity, and output plus terminal connects the 6th electric capacity one end and the 3rd resistance one end, exports one end that negative terminal connects the 5th electric capacity one end and the second resistance;
One end of positive termination the 6th electric capacity of described 4th amplifier, negative terminal connects one end of the 5th electric capacity, and output plus terminal connects the 8th electric capacity one end, exports negative terminal and connects the 7th electric capacity one end;
One end of positive termination the 8th electric capacity of described 5th amplifier, negative terminal connects one end of the 7th electric capacity, exports detecting circuit described in termination.
The output negative terminal of the first amplifier described in one termination of described first electric capacity, the negative terminal of the second amplifier described in another termination;
The output plus terminal of the first amplifier described in one termination of described second electric capacity, the anode of the second amplifier described in another termination;
The output negative terminal of the second amplifier described in one termination of described 3rd electric capacity, the negative terminal of the 3rd amplifier described in another termination;
The output plus terminal of the second amplifier described in one termination of described 4th electric capacity, the anode of the 3rd amplifier described in another termination;
The output negative terminal of the 3rd amplifier described in one termination of described 5th electric capacity, the negative terminal of the 4th amplifier described in another termination;
The output plus terminal of the 3rd amplifier described in one termination of described 6th electric capacity, the anode of the 4th amplifier described in another termination;
The output negative terminal of the 4th amplifier described in one termination of described 7th electric capacity, the negative terminal of the 5th amplifier described in another termination;
The output plus terminal of the 4th amplifier described in one termination of described 8th electric capacity, the anode of the 5th amplifier described in another termination;
The output of frequency changer circuit and the anode of described first amplifier described in described first resistance one termination, the negative terminal of the first amplifier described in another termination;
The output negative terminal of the 3rd amplifier described in one termination of described second resistance, noise suppression circuit described in another termination and described 3rd resistance;
The output plus terminal of the 3rd amplifier, noise suppression circuit described in another termination and described second resistance described in one termination of described 3rd resistance.
Described first amplifier, the second amplifier, the 3rd amplifier, the 4th amplifier are all the same with the internal structure of the 5th amplifier, specifically comprise the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, a NPN pipe, the 2nd NPN pipe:
One termination reference voltage of described 4th resistance, one end of the 5th resistance described in another termination and one end of described 6th resistance;
One end of 4th resistance described in one termination of described 5th resistance and one end of described 6th resistance, the negative terminal input of self amplifier of another termination and the base stage of described 2nd NPN pipe;
One end of 4th resistance described in one termination of described 6th resistance and one end of described 5th resistance, the anode input of self amplifier of another termination and the base stage of a described NPN pipe;
One termination power of described 7th resistance, one end of the 8th resistance described in another termination and one end of described 9th resistance;
One end of 7th resistance described in one termination of described 8th resistance and one end of described 9th resistance, the collector electrode of a NPN pipe described in another termination and amplifier anode export;
One end of 7th resistance described in one termination of described 9th resistance and one end of described 8th resistance, the collector electrode of the 2nd NPN pipe described in another termination and amplifier negative terminal export;
The emitter of a NPN pipe and described 2nd NPN pipe described in one termination of described tenth resistance, other end ground connection;
The base stage of a described NPN pipe connects the anode input of amplifier and one end of described 6th resistance, and the anode of one end and amplifier that collector electrode connects described 8th resistance exports, and emitter connects the emitter of described 2nd NPN pipe and one end of described tenth resistance;
The base stage of described 2nd NPN pipe connects the negative terminal input of amplifier and one end of described 5th resistance, and the negative terminal of one end and amplifier that collector electrode connects described 9th resistance exports, and emitter connects the emitter of a described NPN pipe and one end of described tenth resistance.
Described noise suppression circuit comprises the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the 16 resistance, the 17 resistance, the 18 resistance, the first PNP pipe, the second PNP pipe, the 3rd NPN pipe, the 4th NPN pipe, the 5th NPN pipe and the 6th NPN and manages:
One termination power of described 11 resistance, the emitter of the first PNP pipe described in another termination;
The emitter of the 3rd NPN pipe described in one termination of described 12 resistance, other end ground connection;
One termination power of described 13 resistance, the collector electrode of the 4th NPN pipe described in another termination and the base stage of described 5th NPN pipe;
The emitter of the 4th NPN pipe described in one termination of described 14 resistance, other end ground connection;
One termination power of described 15 resistance, one end of the 17 resistance described in another termination and the base stage of described second PNP pipe;
One termination power of described 16 resistance, the emitter of the second PNP pipe described in another termination;
One end of 15 resistance and the base stage of described second PNP pipe described in one termination of described 17 resistance, the collector electrode of the 5th NPN pipe described in another termination;
The collector electrode of the second PNP pipe described in one termination of described 18 resistance and the base stage of described 6th NPN pipe;
The base stage of described first PNP pipe connects the other end output of intermediate frequency amplifier circuit, and collector electrode connects collector electrode and the base stage of described 3rd NPN pipe, and emitter connects one end of described 11 resistance;
The base stage of described second PNP pipe connects one end of described 15 resistance and one end of described 17 resistance, and collector electrode connects one end of described 18 resistance and the base stage of described 6th NPN pipe, and emitter connects one end of described 16 resistance;
The base stage of described 3rd NPN pipe connects the collector electrode of collector electrode and described first PNP pipe, and emitter connects one end of described 12 resistance;
The base stage of described 4th NPN pipe connects the base stage of described 3rd NPN pipe, and collector electrode connects one end of described 13 resistance and the base stage of described 5th NPN pipe, and emitter connects one end of described 14 resistance;
The base stage of described 5th NPN pipe connects one end of described 13 resistance and the collector electrode of described 4th NPN pipe, and collector electrode connects one end of described 17 resistance, grounded emitter;
The base stage of described 6th NPN pipe connects the collector electrode of described second PNP pipe and one end of described 18 resistance, and collector electrode connects the input of described audio frequency pre-amplification circuit, grounded emitter.
When receiving FM signal, the base voltage of described first PNP pipe reaches and can make the first PNP pipe work, described 3rd NPN pipe has electric current to pass through, and is mirrored to described 4th NPN pipe, the base voltage of described 5th NPN pipe is dragged down, when low to when the 5th NPN pipe can not be made to work, described second PNP pipe also not conducting, to such an extent as to described 6th NPN pipe does not work, the collector electrode of the 6th NPN pipe is unsettled, now do not affect the input signal of audio amplifier circuit, have the audio signal after amplification to export; When not receiving FM signal, the base voltage of described first PNP pipe is high to making the first PNP pipe not work, described 3rd NPN pipe and described 4th NPN pipe all do not have electric current to pass through, now the base voltage of described 5th NPN pipe is driven high, make the 5th NPN pipe degree of depth conducting, the base voltage of described second PNP pipe is dragged down, the base voltage of described 6th NPN pipe is raised, the collector electrode of the 6th NPN pipe is dragged down, now the input of audio frequency pre-amplification circuit is moved to zero, to such an extent as to do not have signal to export, play restraint speckle effect.
Described audio frequency pre-amplification circuit is made up of an Open-loop amplifier, the output of detecting circuit described in the positive termination of Open-loop amplifier and the output of described noise suppression circuit, the negativing ending grounding of Open-loop amplifier, the output of Open-loop amplifier connects the anode input of described audio power amplifying circuit.
Described audio power amplifying circuit comprises closed loop amplifier, the 19 resistance, the 20 resistance, the 21 resistance, the 9th electric capacity and the tenth electric capacity:
The output of audio frequency pre-amplification circuit described in the positive termination of described closed loop amplifier, negative terminal connects one end of described 19 resistance and one end of described 20 resistance, exports one end of the 19 resistance and one end of described tenth electric capacity described in termination;
One termination closed loop amplifier negative terminal of described 19 resistance, another termination closed loop amplifier exports;
One termination closed loop amplifier negative terminal of described 20 resistance, one end of the tenth electric capacity described in another termination;
The negative terminal of closed loop amplifier described in one termination of described 21 resistance, one end of another termination the 9th electric capacity;
One end of 21 resistance described in one termination of described 9th electric capacity, other end ground connection;
One end of 20 resistance described in one termination of described tenth electric capacity, the output of another termination closed loop amplifier.
The method of noise suppressed, comprises the steps:
(1) high-frequency signal that antenna receives chooses the signal of a certain frequency by tuning circuit;
(2) input circuit is sent in frequency changer circuit to mix and is produced intermediate frequency together with wireless local oscillation frequency;
(3) intermediate-freuqncy signal after intermediate frequency amplifier circuit amplification demodulates audio signal and filtering high-frequency signal through detection; Meanwhile, if do not receive FM signal, now noise suppression circuit is started working, and the input of audio frequency pre-amplification circuit is moved to zero, does not have output audio signal; If receive FM signal, now noise suppression circuit does not work, and the unsettled input signal not affecting audio frequency pre-amplification circuit of output of noise suppression circuit, has the audio signal after amplification to export;
(4) after audio frequency pre-amplification and power amplification, promote loud speaker and sound;
(5) step (1)-(4) are repeated.
The present invention is utilized to suppress by the noise effectively when not receiving FM signal.
Accompanying drawing explanation
Fig. 1 is the structure chart of existing frequency modulation machine.
Fig. 2 is the structure chart with the frequency modulation machine of noise suppression circuit of the present invention.
Fig. 3 is the circuit diagram of the intermediate frequency amplifier circuit of frequency modulation machine of the present invention.
Fig. 4 is the circuit diagram of the amplifier of Fig. 3.
Fig. 5 is the circuit diagram of noise suppression circuit of the present invention.
Fig. 6 is the circuit diagram of audio frequency pre-amplification circuit of the present invention and audio power amplifying circuit.
Embodiment
Below in conjunction with accompanying drawing, content of the present invention is further illustrated.
As shown in Figure 2, for having the frequency modulation machine structure chart of noise suppression circuit, comprise tuning circuit 101, frequency changer circuit 102, intermediate frequency amplifier circuit 103, noise suppression circuit 107, detecting circuit 104, audio frequency pre-amplification circuit 105 and audio power amplifying circuit 106:
Described tuning circuit 101 is the signals in order to choose some frequencies;
Described frequency changer circuit 102 carries out mixing to the tuning signal 111 chosen and local oscillator, therefrom obtains intermediate-freuqncy signal 112;
Described intermediate frequency amplifier circuit 103 is amplified the intermediate-freuqncy signal 112 that described frequency changer circuit 102 obtains, to such an extent as to reach the requirement of detecting circuit 104;
Described noise suppression circuit 107 suppresses the noise when not receiving FM signal;
Described detecting circuit 104 is audio signal from demodulation audio pack out, filtering high-frequency signal;
Described audio frequency pre-amplification circuit 105 carries out open loop pre-amplification to the audio signal 114 that detection exports;
Described audio power amplifying circuit 106 carries out closed loop amplification to audio signal, to reaching promotion loud speaker.
As shown in Figure 3, be the circuit diagram of intermediate frequency amplifier circuit 103.
Intermediate frequency amplifier circuit 103 comprises the first amplifier 301, second amplifier 302, the 3rd amplifier 303, the 4th amplifier 304, the 5th amplifier 305, first electric capacity 309, second electric capacity 312, the 3rd electric capacity 315, the 4th electric capacity 318, the 5th electric capacity 321, the 6th electric capacity 324, the 7th electric capacity 327, the 8th electric capacity 330, first resistance 306, second resistance 332 and the 3rd resistance 333:
The signal 112 that frequency changer circuit 102 described in the positive termination of described first amplifier 301 exports, negative terminal connects the first resistance 306 to anode, and output plus terminal 311 connects second electric capacity 312 one end, exports negative terminal 308 and connects first electric capacity 309 one end;
One end of positive termination second electric capacity 312 of described second amplifier 302, negative terminal connects one end of the first electric capacity 309, and output plus terminal 317 connects the 4th electric capacity 318 one end, exports negative terminal 314 and connects the 3rd electric capacity 315 one end;
One end of positive termination the 4th electric capacity 318 of described 3rd amplifier 303, negative terminal connects one end of the 3rd electric capacity 315, output plus terminal 323 connects the 6th electric capacity 324 one end and the 3rd resistance 333 one end, exports one end that negative terminal 320 connects the 5th electric capacity 321 one end and the second resistance 332;
One end of positive termination the 6th electric capacity 324 of described 4th amplifier 304, negative terminal connects one end of the 5th electric capacity 321, and output plus terminal 329 connects the 8th electric capacity 330 one end, exports negative terminal 326 and connects the 7th electric capacity 327 one end;
One end of positive termination the 8th electric capacity 330 of described 5th amplifier 305, negative terminal connects one end of the 7th electric capacity 327, and output 113 connects described detecting circuit 104.
The output negative terminal 308 of the first amplifier 301 described in one termination of described first electric capacity 309, the negative terminal 310 of the second amplifier 302 described in another termination;
The output plus terminal 311 of the first amplifier 301 described in one termination of described second electric capacity 312, the anode 313 of the second amplifier 302 described in another termination;
The output negative terminal 314 of the second amplifier 302 described in one termination of described 3rd electric capacity 315, the negative terminal 316 of the 3rd amplifier 303 described in another termination;
The output plus terminal 317 of the second amplifier 302 described in one termination of described 4th electric capacity 318, the anode 319 of the 3rd amplifier 303 described in another termination;
The output negative terminal 320 of the 3rd amplifier 303 described in one termination of described 5th electric capacity 321, the negative terminal 322 of the 4th amplifier 304 described in another termination;
The output plus terminal 323 of the 3rd amplifier 303 described in one termination of described 6th electric capacity 324, the anode 325 of the 4th amplifier 304 described in another termination;
The output negative terminal 326 of the 4th amplifier 304 described in one termination of described 7th electric capacity 327, the negative terminal 328 of the 5th amplifier 305 described in another termination;
The output plus terminal 329 of the 4th amplifier 304 described in one termination of described 8th electric capacity 330, the anode 331 of the 5th amplifier 305 described in another termination;
The output 112 of frequency changer circuit 102 described in described first resistance 306 1 termination and the anode of described first amplifier 301, the negative terminal 307 of the first amplifier 301 described in another termination;
The output negative terminal 320 of the 3rd amplifier 303 described in one termination of described second resistance 332, noise suppression circuit 107 described in another termination and described 3rd resistance 333;
The output plus terminal 323 of the 3rd amplifier 303 described in one termination of described 3rd resistance 333, noise suppression circuit 107 described in another termination and described second resistance 332.
Described first amplifier 301, second amplifier 302, the 3rd amplifier 303, the 4th amplifier 304 are all the same with the internal structure of the 5th amplifier 305, internal circuit as shown in Figure 4, specifically comprises the 4th resistance 404, the 5th resistance 406, the 6th resistance 407, the 7th resistance 408, the 8th resistance 410, the 9th resistance 411, the tenth resistance 415, a NPN pipe 412, the 2nd NPN pipe 413:
One termination reference voltage 403 of described 4th resistance 404, one end of the 5th resistance 406 described in another termination and one end of described 6th resistance 407;
One end of 4th resistance 404 described in one termination of described 5th resistance 406 and one end of described 6th resistance 407, the negative terminal input 402 of self amplifier of another termination and the base stage of described 2nd NPN pipe 413;
One end of 4th resistance 404 described in one termination of described 6th resistance 407 and one end of described 5th resistance 406, the anode input 401 of self amplifier of another termination and the base stage of a described NPN pipe 412;
One termination power VCC of described 7th resistance 408, one end of the 8th resistance 410 described in another termination and one end of described 9th resistance 411;
One end of 7th resistance 408 described in one termination of described 8th resistance 410 and one end of described 9th resistance 411, the collector electrode of a NPN pipe 412 described in another termination and amplifier anode export 416;
One end of 7th resistance 408 described in one termination of described 9th resistance 411 and one end of described 8th resistance 410, the collector electrode of the 2nd NPN pipe 413 described in another termination and amplifier negative terminal export 417;
The emitter of a NPN pipe 412 and described 2nd NPN pipe 413 described in one termination of described tenth resistance 415, other end ground connection;
The base stage of a described NPN pipe 412 connects the anode input 401 of amplifier and one end of described 6th resistance 407, the anode of one end and amplifier that collector electrode connects described 8th resistance 410 exports 416, and emitter connects the emitter of described 2nd NPN pipe 413 and one end of described tenth resistance 415;
The base stage of described 2nd NPN pipe 413 connects the negative terminal input 402 of amplifier and one end of described 5th resistance 406, the negative terminal of one end and amplifier that collector electrode connects described 9th resistance 411 exports 417, and emitter connects the emitter of a described NPN pipe 412 and one end of described tenth resistance 415.
As shown in Figure 5, be the circuit diagram of described noise suppression circuit 107.
Described noise suppression circuit 107 comprises the 11 resistance the 502, the 12 resistance the 505, the 13 resistance the 508, the 14 resistance the 506, the 15 resistance the 512, the 16 resistance the 513, the 17 resistance the 511, the 18 resistance 515, first PNP pipe 501, second PNP pipe 514, the 3rd NPN pipe 504, the 4th NPN pipe 507, the 5th NPN pipe 510 and the 6th NPN pipe 516:
One termination power VCC of described 11 resistance 502, the emitter of the first PNP pipe 501 described in another termination;
The emitter of the 3rd NPN pipe 504 described in one termination of described 12 resistance 505, other end ground connection;
One termination power VCC of described 13 resistance 508, the collector electrode of the 4th NPN pipe 507 described in another termination and the base stage of described 5th NPN pipe 510;
The emitter of the 4th NPN pipe 507 described in one termination of described 14 resistance 506, other end ground connection;
One termination power VCC of described 15 resistance 512, one end of the 17 resistance 511 described in another termination and the base stage of described second PNP pipe 514;
One termination power VCC of described 16 resistance 513, the emitter of the second PNP pipe 514 described in another termination;
One end of 15 resistance 512 described in one termination of described 17 resistance 511 and the base stage of described second PNP pipe 514, the collector electrode of the 5th NPN pipe 510 described in another termination;
The collector electrode of the second PNP pipe 514 described in one termination of described 18 resistance 515 and the base stage of described 6th NPN pipe 516;
The base stage of described first PNP pipe 501 connects the other end output of intermediate frequency amplifier circuit 103, and collector electrode connects collector electrode and the base stage of described 3rd NPN pipe 504, and emitter connects one end of described 11 resistance 502;
The base stage of described second PNP pipe 514 connects one end of described 15 resistance 512 and one end of described 17 resistance 511, collector electrode connects one end of described 18 resistance 515 and the base stage of described 6th NPN pipe 516, and emitter connects one end of described 16 resistance 513;
The base stage of described 3rd NPN pipe 504 connects the collector electrode of collector electrode and described first PNP pipe 501, and emitter connects one end of described 12 resistance 505;
The base stage of described 4th NPN pipe 507 connects the base stage of described 3rd NPN pipe 504, and collector electrode connects one end of described 13 resistance 508 and the base stage of described 5th NPN pipe 510, and emitter connects one end of described 14 resistance 506;
The base stage of described 5th NPN pipe 510 connects one end of described 13 resistance 508 and the collector electrode of described 4th NPN pipe 507, and collector electrode connects one end of described 17 resistance 511, grounded emitter;
The collector electrode of the second PNP pipe 514 described in the base stage of described 6th NPN pipe 516 and one end of described 18 resistance 515, collector electrode connects the input of described audio frequency pre-amplification circuit 105, grounded emitter.
When receiving FM signal, the base voltage of described first PNP pipe 501 reaches and the first PNP pipe 501 can be made to work, described 3rd NPN pipe 504 has electric current to pass through, be mirrored to described 4th NPN pipe 507, the base voltage of described 5th NPN pipe 510 is dragged down, when low to when the 5th NPN pipe 510 can not be made to work, described second PNP pipe also not conducting, to such an extent as to described 6th NPN pipe 516 does not work, the collector electrode of the 6th NPN pipe 516 is unsettled, now do not affect the input signal of audio amplifier circuit, have the audio signal after amplification to export, when not receiving FM signal, the base voltage of described first PNP pipe 501 is high to making the first PNP pipe 501 not work, described 3rd NPN pipe 504 and described 4th NPN pipe 507 all do not have electric current to pass through, now the base voltage of described 5th NPN pipe 510 is driven high, make the 5th NPN pipe 510 degree of depth conducting, the base voltage of described second PNP pipe 514 is dragged down, the base voltage of described 6th NPN pipe 516 is raised, the collector electrode of the 6th NPN pipe 516 is dragged down, now the input of audio frequency pre-amplification circuit is moved to zero, to such an extent as to do not have signal to export, play restraint speckle effect.
As shown in Figure 6, be the circuit diagram of audio frequency pre-amplification circuit and audio power amplifying circuit.
Described audio frequency pre-amplification circuit 105 is made up of an Open-loop amplifier 601, the output of detecting circuit 104 described in the positive termination of Open-loop amplifier 601 and the output of described noise suppression circuit 107, the negativing ending grounding of Open-loop amplifier 601, the output of Open-loop amplifier 601 connects the anode input of described audio power amplifying circuit 106.
Described audio power amplifying circuit 106 comprises closed loop amplifier the 602, the 19 resistance the 603, the 20 resistance the 604, the 21 resistance 606, the 9th electric capacity 607 and the tenth electric capacity 605:
The output 115 of audio frequency pre-amplification circuit 105 described in the positive termination of described closed loop amplifier 602, negative terminal connects one end of described 19 resistance 603 and one end of described 20 resistance 604, and output 116 connects one end of described 19 resistance 603 and one end of described tenth electric capacity 605;
One termination closed loop amplifier 602 negative terminal of described 19 resistance 603, another termination closed loop amplifier 602 exports;
One termination closed loop amplifier 602 negative terminal of described 20 resistance 604, one end of the tenth electric capacity 605 described in another termination;
The negative terminal of closed loop amplifier 602 described in one termination of described 21 resistance 606, one end of another termination the 9th electric capacity 607;
One end of 21 resistance 606 described in one termination of described 9th electric capacity 607, other end ground connection;
One end of 20 resistance 604 described in one termination of described tenth electric capacity 605, the output of another termination closed loop amplifier 602.
The invention discloses and a kind of noise suppression circuit for frequency modulation machine and method thereof are provided, and describe the specific embodiment of the present invention and effect with reference to the accompanying drawings.It is understood that above-described embodiment is just to explanation of the present invention, instead of limitation of the present invention, any innovation and creation do not exceeded in spirit of the present invention, all fall within scope.
Claims (6)
1. there is the frequency modulation machine of noise suppression circuit, comprise tuning circuit, frequency changer circuit, intermediate frequency amplifier circuit, detecting circuit, audio frequency pre-amplification circuit, audio power amplifying circuit and noise suppression circuit:
Described tuning circuit is the signal in order to choose some frequencies;
Described frequency changer circuit carries out mixing to the tuning signal chosen and local oscillator, therefrom obtains intermediate-freuqncy signal;
Described intermediate frequency amplifier circuit is amplified the intermediate-freuqncy signal that described frequency changer circuit obtains, to such an extent as to reach the requirement of detecting circuit;
Described detecting circuit is audio signal from demodulation audio pack out, filtering high-frequency signal;
Described audio frequency pre-amplification circuit carries out open loop pre-amplification to the audio signal that detection exports;
Described audio power amplifying circuit carries out closed loop amplification to audio signal, to reaching promotion loud speaker;
Described noise suppression circuit suppresses the noise when not receiving FM signal;
It is characterized in that: described noise suppression circuit comprises the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the 16 resistance, the 17 resistance, the 18 resistance, the first PNP pipe, the second PNP pipe, the 3rd NPN pipe, the 4th NPN pipe, the 5th NPN pipe and the 6th NPN and manages:
One termination power of described 11 resistance, the emitter of the first PNP pipe described in another termination;
The emitter of the 3rd NPN pipe described in one termination of described 12 resistance, other end ground connection;
One termination power of described 13 resistance, the collector electrode of the 4th NPN pipe described in another termination and the base stage of described 5th NPN pipe;
The emitter of the 4th NPN pipe described in one termination of described 14 resistance, other end ground connection;
One termination power of described 15 resistance, one end of the 17 resistance described in another termination and the base stage of described second PNP pipe;
One termination power of described 16 resistance, the emitter of the second PNP pipe described in another termination;
One end of 15 resistance and the base stage of described second PNP pipe described in one termination of described 17 resistance, the collector electrode of the 5th NPN pipe described in another termination;
The collector electrode of the second PNP pipe described in one termination of described 18 resistance and the base stage of described 6th NPN pipe;
The base stage of described first PNP pipe connects the other end output of intermediate frequency amplifier circuit, and collector electrode connects collector electrode and the base stage of described 3rd NPN pipe, and emitter connects one end of described 11 resistance;
The base stage of described second PNP pipe connects one end of described 15 resistance and one end of described 17 resistance, and collector electrode connects one end of described 18 resistance and the base stage of described 6th NPN pipe, and emitter connects one end of described 16 resistance;
The base stage of described 3rd NPN pipe connects the collector electrode of collector electrode and described first PNP pipe, and emitter connects one end of described 12 resistance;
The base stage of described 4th NPN pipe connects the base stage of described 3rd NPN pipe, and collector electrode connects one end of described 13 resistance and the base stage of described 5th NPN pipe, and emitter connects one end of described 14 resistance;
The base stage of described 5th NPN pipe connects one end of described 13 resistance and the collector electrode of described 4th NPN pipe, and collector electrode connects one end of described 17 resistance, grounded emitter;
The base stage of described 6th NPN pipe connects the collector electrode of described second PNP pipe and one end of described 18 resistance, and collector electrode connects the input of described audio frequency pre-amplification circuit, grounded emitter;
When receiving FM signal, the base voltage of described first PNP pipe reaches and can make the first PNP pipe work, described 3rd NPN pipe has electric current to pass through, and is mirrored to described 4th NPN pipe, the base voltage of described 5th NPN pipe is dragged down, when low to when the 5th NPN pipe can not be made to work, described second PNP pipe also not conducting, to such an extent as to described 6th NPN pipe does not work, the collector electrode of the 6th NPN pipe is unsettled, now do not affect the input signal of audio amplifier circuit, have the audio signal after amplification to export;
When not receiving FM signal, the base voltage of described first PNP pipe is high to making the first PNP pipe not work, described 3rd NPN pipe and described 4th NPN pipe all do not have electric current to pass through, now the base voltage of described 5th NPN pipe is driven high, make the 5th NPN pipe degree of depth conducting, the base voltage of described second PNP pipe is dragged down, the base voltage of described 6th NPN pipe is raised, the collector electrode of the 6th NPN pipe is dragged down, now the input of audio frequency pre-amplification circuit is moved to zero, to such an extent as to do not have signal to export, play restraint speckle effect.
2. there is the frequency modulation machine of noise suppression circuit as claimed in claim 1, it is characterized in that described intermediate frequency amplifier circuit comprises the first amplifier, the second amplifier, the 3rd amplifier, the 4th amplifier, the 5th amplifier, the first electric capacity, the second electric capacity, the 3rd electric capacity, the 4th electric capacity, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, the first resistance, the second resistance and the 3rd resistance:
The signal that frequency changer circuit described in the positive termination of described first amplifier exports, negative terminal connects the first resistance to anode, and output plus terminal connects second electric capacity one end, exports negative terminal and connects first electric capacity one end;
One end of positive termination second electric capacity of described second amplifier, negative terminal connects one end of the first electric capacity, and output plus terminal connects the 4th electric capacity one end, exports negative terminal and connects the 3rd electric capacity one end;
One end of positive termination the 4th electric capacity of described 3rd amplifier, negative terminal connects one end of the 3rd electric capacity, and output plus terminal connects the 6th electric capacity one end and the 3rd resistance one end, exports one end that negative terminal connects the 5th electric capacity one end and the second resistance;
One end of positive termination the 6th electric capacity of described 4th amplifier, negative terminal connects one end of the 5th electric capacity, and output plus terminal connects the 8th electric capacity one end, exports negative terminal and connects the 7th electric capacity one end;
One end of positive termination the 8th electric capacity of described 5th amplifier, negative terminal connects one end of the 7th electric capacity, exports detecting circuit described in termination;
The output negative terminal of the first amplifier described in one termination of described first electric capacity, the negative terminal of the second amplifier described in another termination;
The output plus terminal of the first amplifier described in one termination of described second electric capacity, the anode of the second amplifier described in another termination;
The output negative terminal of the second amplifier described in one termination of described 3rd electric capacity, the negative terminal of the 3rd amplifier described in another termination;
The output plus terminal of the second amplifier described in one termination of described 4th electric capacity, the anode of the 3rd amplifier described in another termination;
The output negative terminal of the 3rd amplifier described in one termination of described 5th electric capacity, the negative terminal of the 4th amplifier described in another termination;
The output plus terminal of the 3rd amplifier described in one termination of described 6th electric capacity, the anode of the 4th amplifier described in another termination;
The output negative terminal of the 4th amplifier described in one termination of described 7th electric capacity, the negative terminal of the 5th amplifier described in another termination;
The output plus terminal of the 4th amplifier described in one termination of described 8th electric capacity, the anode of the 5th amplifier described in another termination;
The output of frequency changer circuit and the anode of described first amplifier described in described first resistance one termination, the negative terminal of the first amplifier described in another termination;
The output negative terminal of the 3rd amplifier described in one termination of described second resistance, noise suppression circuit described in another termination and described 3rd resistance;
The output plus terminal of the 3rd amplifier, noise suppression circuit described in another termination and described second resistance described in one termination of described 3rd resistance.
3. there is the frequency modulation machine of noise suppression circuit as claimed in claim 2, it is characterized in that described first amplifier comprises the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, a NPN pipe, the 2nd NPN pipe:
One termination reference voltage of described 4th resistance, one end of the 5th resistance described in another termination and one end of described 6th resistance;
One end of 4th resistance described in one termination of described 5th resistance and one end of described 6th resistance, the negative terminal input of another termination first amplifier and the base stage of described 2nd NPN pipe;
One end of 4th resistance described in one termination of described 6th resistance and one end of described 5th resistance, the anode input of another termination first amplifier and the base stage of a described NPN pipe;
One termination power of described 7th resistance, one end of the 8th resistance described in another termination and one end of described 9th resistance;
One end of 7th resistance described in one termination of described 8th resistance and one end of described 9th resistance, the collector electrode of a NPN pipe described in another termination and amplifier anode export;
One end of 7th resistance described in one termination of described 9th resistance and one end of described 8th resistance, the collector electrode of the 2nd NPN pipe described in another termination and amplifier negative terminal export;
The emitter of a NPN pipe and described 2nd NPN pipe described in one termination of described tenth resistance, other end ground connection;
The base stage of a described NPN pipe connects the anode input of amplifier and one end of described 6th resistance, and the anode of one end and amplifier that collector electrode connects described 8th resistance exports, and emitter connects the emitter of described 2nd NPN pipe and one end of described tenth resistance;
The base stage of described 2nd NPN pipe connects the negative terminal input of amplifier and one end of described 5th resistance, and the negative terminal of one end and amplifier that collector electrode connects described 9th resistance exports, and emitter connects the emitter of a described NPN pipe and one end of described tenth resistance.
4. there is the frequency modulation machine of noise suppression circuit as claimed in claim 2, it is characterized in that described second amplifier, the 3rd amplifier, the 4th amplifier are the same with the structure of described first amplifier with the structure of the 5th amplifier.
5. there is the frequency modulation machine of noise suppression circuit as claimed in claim 1, it is characterized in that described audio frequency pre-amplification circuit comprises Open-loop amplifier, the output of detecting circuit described in the positive termination of Open-loop amplifier and the output of described noise suppression circuit, the negativing ending grounding of Open-loop amplifier, the output of Open-loop amplifier connects the anode input of described audio power amplifying circuit.
6. there is the frequency modulation machine of noise suppression circuit as claimed in claim 1, it is characterized in that described audio power amplifying circuit comprises closed loop amplifier, the 19 resistance, the 20 resistance, the 21 resistance, the 9th electric capacity and the tenth electric capacity:
The output of audio frequency pre-amplification circuit described in the positive termination of described closed loop amplifier, negative terminal connects one end of described 19 resistance and one end of described 20 resistance, exports one end of the 19 resistance and one end of described tenth electric capacity described in termination;
One termination closed loop amplifier negative terminal of described 19 resistance, another termination closed loop amplifier exports;
One termination closed loop amplifier negative terminal of described 20 resistance, one end of the tenth electric capacity described in another termination;
The negative terminal of closed loop amplifier described in one termination of described 21 resistance, one end of another termination the 9th electric capacity;
One end of 21 resistance described in one termination of described 9th electric capacity, other end ground connection;
One end of 20 resistance described in one termination of described tenth electric capacity, the output of another termination closed loop amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210039785.4A CN102545785B (en) | 2012-02-20 | 2012-02-20 | Noise suppression circuit and method for frequency modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210039785.4A CN102545785B (en) | 2012-02-20 | 2012-02-20 | Noise suppression circuit and method for frequency modulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102545785A CN102545785A (en) | 2012-07-04 |
| CN102545785B true CN102545785B (en) | 2015-07-08 |
Family
ID=46351881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210039785.4A Expired - Fee Related CN102545785B (en) | 2012-02-20 | 2012-02-20 | Noise suppression circuit and method for frequency modulator |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102545785B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137790A (en) * | 2015-08-31 | 2015-12-09 | 成都科创城科技有限公司 | Hybrid energy power supply voice and video integrated collection device for smart home |
| CN105093956A (en) * | 2015-08-31 | 2015-11-25 | 成都科创城科技有限公司 | Intelligent household infrared module employing wireless induction charging type bracelet |
| CN105100736A (en) * | 2015-08-31 | 2015-11-25 | 成都科创城科技有限公司 | Smart home voice-video comprehensive acquisition device |
| CN105093951A (en) * | 2015-08-31 | 2015-11-25 | 成都科创城科技有限公司 | Intelligent household ecological system |
| CN105137793A (en) * | 2015-08-31 | 2015-12-09 | 成都科创城科技有限公司 | Smart home ecological system voice instruction collection device employing mobile bracelet |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006049052A1 (en) * | 2004-11-02 | 2006-05-11 | Matsushita Electric Industrial Co., Ltd. | Noise suppresser |
| JP2007028290A (en) * | 2005-07-19 | 2007-02-01 | Sanyo Electric Co Ltd | Am radio receiving circuit |
| JP2010087603A (en) * | 2008-09-29 | 2010-04-15 | Sanyo Electric Co Ltd | Audio signal processing circuit |
-
2012
- 2012-02-20 CN CN201210039785.4A patent/CN102545785B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN102545785A (en) | 2012-07-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102545785B (en) | Noise suppression circuit and method for frequency modulator | |
| US9026073B2 (en) | Device for receiving signals, antenna device and mobile terminal | |
| CN203537555U (en) | Audio device | |
| CN101827295A (en) | Wireless microphone and anti-interference method thereof | |
| CN202957973U (en) | High-performance amplitude-modulation wireless microphone | |
| CN202634684U (en) | Frequency modulator having noise suppression circuit | |
| CN204376883U (en) | A kind of miniaturized receiver circuit | |
| CN202737853U (en) | FM transmitter with low power and high sensitivity | |
| CN2919696Y (en) | Radio with interphone | |
| CN100405747C (en) | Radio with interphone | |
| CN201243278Y (en) | Low noise signal amplifier for mobile phone radio built-in antenna | |
| CN205017312U (en) | Seven tubs of superheterodyne AM receivers | |
| CN203180902U (en) | A frequency modulation transmitter with strong anti-interference performance | |
| CN104242831A (en) | Wideband amplification device with low noise | |
| CN202750078U (en) | FM transmitter with low power and high sensitivity | |
| CN206472125U (en) | A kind of low-cost wireless receiver | |
| CN206977411U (en) | A kind of portable construction site calling machine equipment | |
| CN202931294U (en) | High sensitivity FM transmitter | |
| CN202043264U (en) | Frequency modulation wireless microphone circuit with voltage stabilizing circuit | |
| CN203233413U (en) | A simple frequency modulation communication instrument | |
| CN203193616U (en) | Low-power high-sensitivity frequency band transmitter | |
| CN103532572A (en) | Low-power high-sensitivity FM transmitter | |
| CN204408615U (en) | Cable television system stereophonic signal emitter | |
| CN205792534U (en) | A kind of anti-interference wireless radio receiver | |
| CN201600900U (en) | BD player with broadcast receiving function |
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 | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150708 Termination date: 20170220 |