CN103491487B - A kind of frequency modulation anti-interference hidden earphone system - Google Patents
A kind of frequency modulation anti-interference hidden earphone system Download PDFInfo
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- CN103491487B CN103491487B CN201310423621.6A CN201310423621A CN103491487B CN 103491487 B CN103491487 B CN 103491487B CN 201310423621 A CN201310423621 A CN 201310423621A CN 103491487 B CN103491487 B CN 103491487B
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Abstract
The invention discloses a kind of frequency modulation anti-interference hidden earphone system, obtain audio signal for being connected with intercom and FM modulation is carried out to audio signal, it comprises adapter and earphone, and adapter comprises interface module, power module, timbre detection module, gain control module, FM modulation module, signal amplification module; Interface module connects intercom, timbre detection module and gain control module, and gain control module, FM modulation module, signal amplification module connect successively, signal amplification module wireless connections earphone.The present invention is transferred to earphone after carrying out FM process to audio signal, play after carrying out demodulation, DSP process by earphone, compared with FM modulation is modulated with existing AM, its distortion is less, frequency response is wide, signal to noise ratio is high, amplification efficiency is high, anti-noise better effects if, improves the quality of tonequality; By gain control module stationary audio signals, improve communication quality.
Description
Technical field
The present invention relates to communication technical field, particularly a kind of frequency modulation anti-interference hidden earphone system.
Background technology
Current wireless electromagnetic induction earphone adopts frequency induction technology, the direct transmitting audio frequency field signal of transmitting terminal, and earphone receives field signal and is translated into voice signal.But in actual environment, there is many interference sources identical or close with audio frequency, as power frequency, automobile, hair dryer, electric iron, PC screen etc.Therefore ordinary electromagnetic induction earphone is easy to be interfered.And common wireless electromagnetic induction earphone does not have wireless PTT function, inconvenient operation.
Application number be 200680056251.5 patent of invention mention a kind ofly having from the audio signal transmission unit of body worn to the communication system of inductive link comprising micropkonic earphone, can use when sources of magnetic perturbations, its inductive link can carry out the amplitude modulation(PAM) (AM of the carrier frequency from 100KHz ~ 30MHz, amplitudemodulation), described AM inductive link is easier to realize compared to TVM inductive link, receiving equipment is simple, and do not need special integrated circuit (IC), the region of applicable great majority needs hidden safe.
But it is large that AM modulation has distorted signals, and frequency response is not wide, poor signal to noise, and efficiency of amplitude is low, the shortcoming of poor anti jamming capability.
Thus prior art need to improve.
Summary of the invention
In view of above-mentioned the deficiencies in the prior art part, the object of the present invention is to provide a kind of frequency modulation anti-interference hidden earphone system, under low-power, realize FM modulation reduce distortion, increase frequency response width, improve signal to noise ratio, improve efficiency of amplitude, improve antijamming capability, guarantee communication quality.
In order to achieve the above object, this invention takes following technical scheme:
A kind of frequency modulation anti-interference hidden earphone system, obtain audio signal for being connected with intercom and FM modulation is carried out to audio signal, it comprises adapter and earphone, described adapter connects intercom, earphone and adapter wireless connections, wherein, described adapter obtain the voice signal of user and intercom transmission audio signal, FM process is carried out to audio signal after be transferred to earphone, carry out broadcasting after demodulation, DSP process by earphone; Described adapter comprises:
Interface module, for transmitting the audio signal that intercom receives, being launched to intercom by the transmitting voice signal of PTT key controlled user, and providing supply voltage;
Whether timbre detection module, receive audio signal for detecting intercom, and produce an enable signal when there being audio signal to input;
Power module, for converting supply voltage to first operating voltage, and converts supply voltage to second operating voltage according to the enable signal that timbre detection module exports;
Gain control module, the amplitude for automatically adjusting multiplication factor amplification or reduction audio signal generates the consistent audio signal of amplitude;
FM modulation module, carries out FM modulation for the audio signal consistent by amplitude to carrier frequency and generates FM signal;
Signal amplification module, is transmitted to earphone after amplifying FM signal;
Described power module is connection interface module, timbre detection module, gain control module, FM modulation module and signal amplification module respectively, described interface module connects intercom, timbre detection module and gain control module, described gain control module, FM modulation module, signal amplification module connect successively, described signal amplification module wireless connections earphone.
In described frequency modulation anti-interference hidden earphone system, described interface module comprises: radio interface, PTT button, microphone, the first resistance, the second resistance and the first electric capacity; The vdd terminal of described radio interface connects power module, the GND of radio interface holds ground connection, the SPK end of radio interface connects timbre detection module and gain control module, the PTT end of radio interface is by PTT button ground connection, the MIC end of radio interface connects the 1st pin of microphone by the first resistance, 2nd pin of microphone connects one end of the second resistance and the 3rd pin of microphone by the first electric capacity, the other end ground connection of the second resistance.
In described frequency modulation anti-interference hidden earphone system, described power module comprises: the first power supply chip, second source chip, the first filter circuit, the second filter circuit, the first inductance and the second inductance, the VIN end of described first power supply chip is all connected the vdd terminal of radio interface with the IN end of second source chip, the VOUT of the first power supply chip holds the input of connection first filter circuit, the output of the first filter circuit connects timbre detection module by the first inductance, gain control module and FM modulation module, the OUT of second source chip holds the input of connection second filter circuit, the output of the second filter circuit is by the second inductance connection signal amplification module, the CE end of second source chip connects timbre detection module, the GND of the first power supply chip and second source chip holds equal ground connection.
In described frequency modulation anti-interference hidden earphone system, described timbre detection module comprises: timbre input chip, the second electric capacity, the 3rd electric capacity, the 3rd resistance, the 4th resistance and the 5th resistance; The IN end of described timbre input chip connects the SPK end of radio interface successively by the 3rd resistance, the second electric capacity; The vdd terminal of timbre input chip is connected the output of the first filter circuit by the first inductance in power module, is also connected the OUT2 end of timbre input chip by the 5th resistance; The CE that the OUT2 end of described timbre input chip connects second source chip by the 4th resistance holds, also by the 3rd capacity earth.
In described frequency modulation anti-interference hidden earphone system, described gain control module comprises AGC chip, the 4th electric capacity, the 5th electric capacity, the 6th resistance, the 7th resistance, the 8th resistance and the 9th resistance; The IN end of described AGC chip connects one end of the 6th resistance and one end of the 8th resistance by the 4th electric capacity, the other end of the 6th resistance connects the SPK end of radio interface and one end of the 7th resistance, the equal ground connection of the other end of the 7th resistance and the 8th resistance, the VCC end of AGC chip connects the output of the first filter circuit by the first inductance in power module, the OUT end of AGC chip connects one end of FM modulation module and the 5th electric capacity, the other end ground connection of the 5th electric capacity by the 9th resistance.
In described frequency modulation anti-interference hidden earphone system, described FM modulation module comprises VCO chip, the tenth resistance, the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 6th electric capacity and the 7th electric capacity, the VCO_OUT end of described VCO chip connects CI end and the signal amplification module of VCO chip, the CI_1 end of VCO chip connects the CI_2 end of VCO chip by the 6th electric capacity, the vdd terminal of VCO chip connects the output of the first filter circuit by the first inductance in power module, the VCO_IN end of VCO chip connects one end of the tenth resistance by the 7th electric capacity, the other end of described tenth resistance connects one end of the 5th electric capacity in gain control module, described VCO_IN end is also successively by the 7th electric capacity, 11 grounding through resistance, the R1_TO end of VCO chip is by the 12 grounding through resistance, the R2_TO end of VCO chip is successively by the 13 resistance, 14 grounding through resistance.
In described frequency modulation anti-interference hidden earphone system, described signal amplification module comprises amplification chip, induction coil, the 8th electric capacity, the 15 resistance and the 16 resistance; The vdd terminal of described amplification chip connects one end of the second inductance in power module, the IN-end of amplification chip connects the VCO_OUT end of VCO chip in FM modulation module successively by the 8th electric capacity, the 15 resistance, 16 resistance is connected between the IN-end of amplification chip and OUT end, and the OUT end of amplification chip is by induction coil ground connection.
In described frequency modulation anti-interference hidden earphone system, described FM modulation module also comprises the first adjustable resistance and the second adjustable resistance, one end of described first adjustable resistance connects one end of the 5th electric capacity in the adjustable end of the first adjustable resistance, the other end of the tenth resistance and gain control module, and the other end of the first adjustable resistance connects the VCO_IN end of VCO chip by the 7th electric capacity; One end of second adjustable resistance connects the R2_TO end of VCO chip and the adjustable end of the second adjustable resistance, and the other end of the second adjustable resistance is by the 14 grounding through resistance.
In described frequency modulation anti-interference hidden earphone system, described signal amplification module also comprises the 3rd adjustable resistance, one end of described 3rd adjustable resistance connects the IN-end of amplification chip and the adjustable end of the 3rd adjustable resistance, and the other end of the 3rd adjustable resistance connects the OUT end of amplification chip.
In described frequency modulation anti-interference hidden earphone system, also comprise the remote controller for communication control and volume, described adapter also comprises the magnetic field receiving system for communicating with remote controller, and described remote controller connects described magnetic field receiving system.
Compared to prior art, frequency modulation anti-interference hidden earphone system provided by the invention, by adapter, earphone is connected with intercom, obtain by adapter audio signal that the voice signal of user and intercom transmit, FM signal transacting is carried out to audio signal after be transferred to earphone and play, FM modulation and demodulation are realized under low-voltage and low-power, induction frequencies is moved to the frequency range far above audio frequency and interfering frequency, effectively reduces power frequency and other relevant electromagnetic interference, reduce power consumption; By gain control module stationary audio signals, improve communication quality; Compared with FM modulation is modulated with existing AM, it has, and distortion is less, frequency response is wide, signal to noise ratio is high, and amplification efficiency is high, the advantage of anti-noise better effects if, improves the quality of tonequality; In addition, also realize PTT function by the PTT button on adapter, user-friendly.
Accompanying drawing explanation
Fig. 1 is the wireless headset of frequency modulation anti-interference hidden earphone system preferred embodiment of the present invention.
Fig. 2 is the adapter of frequency modulation anti-interference hidden earphone system preferred embodiment of the present invention.
Fig. 3 is frequency modulation anti-interference hidden earphone system structured flowchart of the present invention.
Fig. 4 is the circuit diagram of interface module in frequency modulation anti-interference hidden earphone system of the present invention.
Fig. 5 is the circuit diagram of power module in frequency modulation anti-interference hidden earphone system of the present invention.
Fig. 6 is the circuit diagram of frequency modulation anti-interference hidden earphone system middle pitch product detection module of the present invention.
Fig. 7 is the circuit diagram of gain control module in frequency modulation anti-interference hidden earphone system of the present invention.
Fig. 8 is the circuit diagram of FM modulation module in frequency modulation anti-interference hidden earphone system of the present invention.
Fig. 9 is the circuit diagram of signal amplification module in frequency modulation anti-interference hidden earphone system of the present invention.
Embodiment
The invention provides a kind of frequency modulation anti-interference hidden earphone system, for making object of the present invention, technical scheme and effect clearly, clearly, developing simultaneously referring to accompanying drawing, the present invention is described in more detail for embodiment.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
Please refer to Fig. 1,2,3, frequency modulation anti-interference hidden earphone system provided by the invention is used for being connected with intercom obtaining audio signal and carrying out FM modulation to audio signal, it comprises adapter and earphone 1, and described adapter and earphone 1 wireless connections, with intercom wired connection; Described adapter, for gathering the voice signal of user and receiving the audio signal of intercom transmission and be transferred to earphone after carrying out FM process to audio signal, is play after carrying out demodulation, DSP process by earphone.Wherein, adapter comprises speech processor 2, joint 3, controller 4, coil 5 and plug-in type connector 6.Joint 3 comprises interface module 10.Described speech processor 2 comprises power module 20, timbre detection module 30, gain control module 40, FM modulation module 50 and signal amplification module 60.Described power module 20 connection interface module 10, timbre detection module 30, gain control module 40, FM modulation module 50 and signal amplification module 60, described interface module 10 connects intercom, timbre detection module 30 and gain control module 40, described gain control module 40, FM modulation module 50, signal amplification module 60 connect successively, described signal amplification module 60 wireless connections earphone.
In the specific implementation, joint 3 is connected with the interface of intercom, and the audio signal transmission that the other side's intercom that intercom can receive by interface module 10 is launched is to adapter; Or when PTT button is pressed, the transmitting voice signal that Mike's wind energy that speech processor 2 is arranged obtains user is transmitted in the air to intercom; Interface module 10 is also connected with the electric supply installation of intercom, for whole adapter provides supply voltage.Power module 20 converts the first operating voltage to by supply voltage, for timbre detection module 30, gain control module 40, FM modulation module 50 are powered thus start these modules.Whether timbre detection module 30 receives described audio signal for detecting intercom, produces an enable signal when there being audio signal to input.The enable signal that power module 20 can also export according to timbre detection module 30 converts supply voltage to second operating voltage and powers to signal amplification module 60.Like this when not having audio signal to input, signal amplification module 60 does not start, thus saves electric charge.The amplitude that gain control module 40 adjusts multiplication factor amplification or reduction audio signal automatically generates the basically identical audio signal of amplitude, FM modulation module 50 audio signal that amplitude is consistent carries out FM(FrequencyModulation to carrier frequency, frequency modulation) modulation generation FM signal, launch field signal to earphone 1 after finally being amplified by signal amplification module 60 pairs of FM signals.Be reduced into voice signal through demodulation, DSP process to loudspeaker after earphone 1 receives this field signal, user can hear the other side's sound.
Earphone 1 is put into ear by user in use, is connected by adapter with intercom, is hung over by coil 5 on user's neck, and after connecting connector 6, coil 5 is connected, and namely whole system enters operating state.The visual actual needs of this frequency modulation anti-interference hidden earphone system is hidden in clothes, to realize the effect of hidden call.Adopt FM modulation based on this frequency modulation anti-interference hidden earphone system, the audio distortions that earphone can be made to play is less, frequency response is wide, signal to noise ratio is high, and amplification efficiency is high, anti-noise better effects if.To specifically set forth the circuit implementations of above-mentioned modules below.
Described interface module 10 comprises radio interface J, PTT button K, microphone MIC, the first resistance R1, the second resistance R2 and the first electric capacity C1; The vdd terminal of described radio interface J connects power module 20, the GND of radio interface J holds ground connection, the SPK end of radio interface J connects timbre detection module 30 and gain control module 40, the PTT end of radio interface J is by PTT button K ground connection, the MIC end of radio interface J connects the 1st pin of microphone MIC by the first resistance R1,2nd pin of microphone MIC connects one end of the second resistance R2 and the 3rd pin of microphone MIC by the first electric capacity C1, the other end ground connection of the second resistance R2.
The vdd terminal of described radio interface J connects the external power source pin of intercom simultaneously, and the power supply obtaining intercom provides supply voltage VDD for whole frequency modulation anti-interference hidden earphone system.Described SPK end connects the loudspeaker output of intercom simultaneously, and the voice signal of its other user received by intercom---audio signal SP_IN is transferred to frequency modulation anti-interference hidden earphone system and carries out signal transacting and FM modulation.Described PTT button K is used for realizing PTT(Push-to-Talk, PTT) function, namely when user needs speech, press PTT button K and then on PTT end, produce a low level pulse, now microphone MIC starts and starts the voice signal obtaining user, export voice signal MIC_OUT to intercom by the 1st pin of microphone MIC, the voice signal MIC_OUT of this user is transmitted to the other side's intercom by intercom.So just achieve the function that user voice signal exports and the other user's voice signal inputs.
In the specific implementation, conveniently user uses PTT button, PTT button can be arranged on controller 4.Described controller 4 is also provided with volume adjusting button, the volume of earphone can be adjusted or realize quiet.
Converted to the operating voltage of other modules needs by power module 20 after supply voltage VDD inputs.Described power module 20 comprises: the first power supply chip U1, second source chip U2, the first filter circuit 201, second filter circuit 202, first inductance L 1 and the second inductance L 2, the VIN end of described first power supply chip U1 is all connected the vdd terminal of radio interface J with the IN end of second source chip U2, the VOUT of the first power supply chip U1 holds the input in1 of connection first filter circuit 201, the output out1 of the first filter circuit 201 connects timbre detection module 30 by the first inductance L 1, gain control module 40 and FM modulation module 50, the OUT of second source chip U2 holds the input in2 of connection second filter circuit 202, the output out2 of the second filter circuit 202 is by the second inductance L 2 connection signal amplification module 60, the CE end of second source chip U2 connects timbre detection module 30, the GND of the first power supply chip U1 and second source chip U2 holds equal ground connection.
The first converting unit is formed by the first power supply chip U1, the first filter circuit 201, first inductance L 1 in power module 20, after supply voltage VDD inputs, the first converting unit starts immediately and carries out operating state, first power supply chip U1 changes supply voltage VDD, the voltage exported is through the first filter circuit 201 filtering, and the first inductance L 1 goes to disturb rear generation first operating voltage 3.3V_B.
By second source chip U2 in power module 20, second filter circuit 202, second inductance L 2 forms the second converting unit, after supply voltage VDD inputs, the second converting unit only starts, enter armed state, only have when second source chip U2 detects that enable signal 3.3V_EN that timbre detection module 30 exports just can make the second converting unit enter operating state and realize voltage transitions, second source chip U2 starts and starts to change supply voltage VDD, the voltage exported is through the second filter circuit 202 filtering, second inductance L 2 goes to disturb rear generation second operating voltage 3.3V_A.In the present embodiment, the first filter circuit 201 and the second filter circuit 202 all can adopt the mode of multiple Capacitance parallel connection to realize filtering, make the operating voltage of output more steady.
First operating voltage 3.3V_B inputs timbre detection module 30 makes it enter armed state.Described timbre detection module 30 is for detecting the audio signal SP_IN whether receiving the other user, and it comprises: timbre input chip U3, the second electric capacity C2, the 3rd electric capacity C3, the 3rd resistance R3, the 4th resistance R4 and the 5th resistance R5; The IN end of described timbre input chip U3 connects the SPK end of radio interface J successively by the 3rd resistance R3, the second electric capacity C2; The vdd terminal of timbre input chip U3 is connected the output out1 of the first filter circuit 201 by the first inductance L 1 in power module 20, is also connected the OUT2 end of timbre input chip U3 by the 5th resistance R5; The CE that the OUT2 end of described timbre input chip U3 connects second source chip U2 by the 4th resistance R4 holds, also by the 3rd electric capacity C3 ground connection.
When the audio signal SP_IN input exchanged, timbre input chip U3 starts working, and its enable signal 3.3V_EN exporting a high level controls second source chip U2 work in power module 20 and realizes voltage transitions.When no audio signal SP_IN inputs, timbre input chip U3 does not work and can not realize voltage transitions and generate the second operating voltage 3.3V_A, then signal amplification module 60 does not have operating voltage to start.In other words, timbre detection module 30 plays the effect of detection, and when not having audio signal SP_IN, second source chip U2, timbre input chip U3 and signal amplification module 60 do not start, can electricity be saved, reduce the power consumption of frequency modulation anti-interference hidden earphone system.
The audio signal SP_IN of input needs first by carrying out FM modulation again after gain control module 40 process.Described gain control module 40 comprises AGC chip U4, the 4th electric capacity C4, the 5th electric capacity C5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8 and the 9th resistance R9; The IN end of described AGC chip U4 connects one end of the 6th resistance R6 and one end of the 8th resistance R8 by the 4th electric capacity C4, the other end of the 6th resistance R6 connects the SPK end of radio interface J and one end of the 7th resistance R7, the equal ground connection of the other end of the 7th resistance R7 and the 8th resistance R8, the VCC end of AGC chip U4 connects the output out1 of the first filter circuit 201 by the first inductance L 1 in power module, the OUT end of AGC chip U4 connects one end of FM modulation module 50 and the 5th electric capacity C5, the other end ground connection of the 5th electric capacity C5 by the 9th resistance R9.
AGC(automaticgaincontrol, automatic growth control) chip can automatically increase according to the amplitude size of audio signal SP_IN of input or reduce multiplication factor, to significantly reduce, amplify by a small margin, the audio signal IN_OUT that output amplitude is consistent improves the stability of signal, make follow-uply to carry out FM to modulate the modulation degree of the FM signal obtained relatively stable, thus improve communication quality.
The audio signal IN_OUT that amplitude after AGC process is consistent enters FM modulation module 50 and carries out FM modulation, and described FM modulation module 50 comprises VCO chip U5, the tenth resistance R10, the 11 resistance R11, the 12 resistance R12, the 13 resistance R13, the 14 resistance R14, the 6th electric capacity C6 and the 7th electric capacity C7, the VCO_OUT end of described VCO chip U5 connects its CI and holds and signal amplification module 60, the CI_1 end of VCO chip U5 connects the CI_2 end of VCO chip U5 by the 6th electric capacity C6, the vdd terminal of VCO chip U5 connects the output out1 of the first filter circuit 201 by the first inductance L 1 in power module 20, the VCO_IN end of VCO chip U5 connects one end of the tenth resistance R10 by the 7th electric capacity C7, the other end of described tenth resistance R10 connects the one end of the 5th electric capacity C5 in gain control module 40, described VCO_IN end is also successively by the 7th electric capacity C7, 11 resistance R11 ground connection, the R1_TO end of VCO chip U5 is by the 12 resistance R12 ground connection, the R2_TO end of VCO chip U5 is successively by the 13 electric R13 resistance, 14 resistance R14 ground connection.
The inner self-excitation of described VCO chip U5 produces a carrier frequency, this carrier frequency is controlled to obtain reference frequency by the value of described 6th electric capacity C6 and the 12 resistance R12, the value of described 13 resistance R13 and the 14 resistance R14 controls the displacement of reference frequency, and these electronic devices determine the size of local frequency (being FM signal AU_IN in the present embodiment) jointly.
In order to adapt to the demand of different client, facilitate the adjustment of frequency size, described FM modulation module 50 also comprises the first adjustable resistance Ra and the second adjustable resistance Rb, one end 1 of described first adjustable resistance Ra connects the one end of the 5th electric capacity C5 in the adjustable end 2 of the first adjustable resistance Ra, the other end of the tenth resistance R10 and gain control module 40, and the other end 3 of the first adjustable resistance Ra connects the VCO_IN end of VCO chip U5 by the 7th electric capacity C7; One end 1 of second adjustable resistance Rb connects the other end 3 of the R2_TO end of VCO chip and adjustable end 2, the second adjustable resistance Rb of the second adjustable resistance Rb by the 14 resistance R14 ground connection.
First adjustable resistance Ra can adjust the signal magnitude of signal to VCO_IN, thus adjustment FM modulation degree.Frequency size needed for client, can artificially regulate the resistance of the second adjustable resistance Rb to realize carrier frequency adjustment before dispatching from the factory.In the present embodiment, the capacitance of described 6th electric capacity C6 is 180pF, and the resistance of the 12 resistance R12 is 3.3K ± 1%, and reference frequency is about 187.5KHz.The scope of FM signal AU_IN is 100KHz ~ 2MHz, can meet the demand of exhausted big customer, and modulation is convenient, and FM signal AU_IN is square wave, is convenient to rear class and amplifies process, make the signal effect after amplification better.Meanwhile, compared with FM modulation is modulated with existing AM, it has, and distortion is less, frequency response is wide, signal to noise ratio is high, and amplification efficiency is high, the advantage of anti-noise better effects if, improves the quality of tonequality.
In the specific implementation, in order to the audio signal IN_OUT that level and smooth amplitude is consistent, filter out noise is disturbed, described FM modulation module 50 also comprises filter capacitor, one end of this filter capacitor is connected the VCO_IN end of VCO chip U5, is also connected the other end 3 of the first adjustable resistance Ra by the 7th electric capacity C7, the other end ground connection of described filter capacitor.
Entering signal amplification module 60 after audio modulation signal AU_IN exports from the VCO_OUT end of VCO chip U5, described signal amplification module 60 comprises amplification chip U6, induction coil L3, the 8th electric capacity C8, the 15 resistance R15 and the 16 resistance R16; The vdd terminal of described amplification chip U6 connects one end of the second inductance L 2 in power module 20, the IN-end of amplification chip U6 connects the VCO_OUT end of VCO chip U5 in FM modulation module 50 successively by the 8th electric capacity C8, the 15 resistance R15,16 resistance R16 is connected between the IN-end of amplification chip U6 and OUT end, and the OUT end of amplification chip U6 is by induction coil L3 ground connection.
Described amplification chip U6 adopts amplifier, the resistance of the 16 resistance R16 determines amplification coefficient, in order to the gain of amplifier can be adjusted, described signal amplification module 60 also comprises the 3rd adjustable resistance Rc, the OUT that the other end 3 that one end 1 of described 3rd adjustable resistance Rc connects the IN-end of amplification chip U6 and adjustable end the 2, three adjustable resistance Rc of the 3rd adjustable resistance Rc connects amplification chip U6 holds.In order to eliminate self-excitation, can also an electric capacity in parallel at the two ends of the 6th resistance R16.Audio modulation signal AU_IN launches field signal to earphone by induction coil L3 after amplification chip U6 amplifies, thus realizes sound broadcasting.
In the specific implementation, native system also comprises the remote controller for communication control and volume, and described adapter also comprises the magnetic field receiving system for communicating with remote controller, and described remote controller connects described magnetic field receiving system.More preferably described remote controller is Digiplex, and described magnetic field receiving system adopts nearly magnetic field induction technology, can increase the noiseproof feature of native system.Digiplex arranges another PTT button to realize the call function of PTT, arrange volume adjusting button to increase or reduce volume.Can Digiplex be placed in pocket during use, facilitate the hidden manipulation of user; Communicated with magnetic field receiving system by the wireless communication module in Digiplex after pushing button, the instruction of transmission button operation can carry out call to adapter and volume controls.
In sum, frequency modulation anti-interference hidden earphone system provided by the invention, by adapter, earphone is connected with intercom, detected by the audio signal of adapter to input, when not detecting, partial circuit module is not powered, can electricity be saved, reduce the power consumption of frequency modulation anti-interference hidden earphone system; First AGC process being carried out to it when audio signal being detected, making the substantially identical stability improving signal of the amplitude of the signal of output, then carry out FM and modulate the FM signal obtained.This programme carrier frequency is square wave, to facilitate process, improves efficiency of amplitude.Relative to AM scheme, distortion of the present invention is less, frequency response is wide, signal to noise ratio is high, and amplification efficiency is high, anti-noise better effects if, thus improves communication quality.
Be understandable that, for those of ordinary skills, can be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, and all these change or replace the protection range that all should belong to the claim appended by the present invention.
Claims (9)
1. a frequency modulation anti-interference hidden earphone system, obtain audio signal for being connected with intercom and FM modulation is carried out to audio signal, it comprises adapter and earphone, described adapter connects intercom, earphone and adapter wireless connections, it is characterized in that, described adapter for obtain the voice signal of user and intercom transmission audio signal, FM process is carried out to audio signal after be transferred to earphone, carry out broadcasting after demodulation, DSP process by earphone; Described adapter comprises:
Interface module, for transmitting the audio signal that intercom receives, being launched to intercom by the transmitting voice signal of PTT key controlled user, and providing supply voltage;
Whether timbre detection module, receive audio signal for detecting intercom, and produce an enable signal when there being audio signal to input;
Power module, for converting supply voltage to first operating voltage, and converts supply voltage to second operating voltage according to the enable signal that timbre detection module exports;
Gain control module, the amplitude for automatically adjusting multiplication factor amplification or reduction audio signal generates the consistent audio signal of amplitude;
FM modulation module, carries out FM modulation for the audio signal consistent by amplitude to carrier frequency and generates FM signal;
Signal amplification module, is transmitted to earphone after amplifying FM signal;
Described power module is connection interface module, timbre detection module, gain control module, FM modulation module and signal amplification module respectively, described interface module connects intercom, timbre detection module and gain control module, described gain control module, FM modulation module, signal amplification module connect successively, described signal amplification module wireless connections earphone;
Described gain control module comprises AGC chip, the 4th electric capacity, the 5th electric capacity, the 6th resistance, the 7th resistance, the 8th resistance and the 9th resistance; The IN end of described AGC chip connects one end of the 6th resistance and one end of the 8th resistance by the 4th electric capacity, the other end connection interface module of the 6th resistance and one end of the 7th resistance, the equal ground connection of the other end of the 7th resistance and the 8th resistance, the VCC end of AGC chip connects power module, the OUT end of AGC chip connects one end of FM modulation module and the 5th electric capacity, the other end ground connection of the 5th electric capacity by the 9th resistance;
AGC chip automatically increases according to the amplitude size of the audio signal of input or reduces multiplication factor, to significantly reduce, amplify by a small margin, the audio signal that output amplitude is consistent improves the stability of signal, makes FM modulate the modulation degree of the FM signal obtained relatively stable.
2. frequency modulation anti-interference hidden earphone system according to claim 1, is characterized in that, described interface module comprises: radio interface, PTT button, microphone, the first resistance, the second resistance and the first electric capacity; The vdd terminal of described radio interface connects power module, the GND of radio interface holds ground connection, the SPK end of radio interface connects timbre detection module and gain control module, the PTT end of radio interface is by PTT button ground connection, the MIC end of radio interface connects the 1st pin of microphone by the first resistance, 2nd pin of microphone connects one end of the second resistance and the 3rd pin of microphone by the first electric capacity, the other end ground connection of the second resistance.
3. frequency modulation anti-interference hidden earphone system according to claim 2, is characterized in that, described power module comprises: the first power supply chip, second source chip, the first filter circuit, the second filter circuit, the first inductance and the second inductance, the VIN end of described first power supply chip is all connected the vdd terminal of radio interface with the IN end of second source chip, the VOUT of the first power supply chip holds the input of connection first filter circuit, the output of the first filter circuit connects timbre detection module by the first inductance, gain control module and FM modulation module, the OUT of second source chip holds the input of connection second filter circuit, the output of the second filter circuit is by the second inductance connection signal amplification module, the CE end of second source chip connects timbre detection module, the GND of the first power supply chip and second source chip holds equal ground connection.
4. frequency modulation anti-interference hidden earphone system according to claim 3, is characterized in that, described timbre detection module comprises: timbre input chip, the second electric capacity, the 3rd electric capacity, the 3rd resistance, the 4th resistance and the 5th resistance; The IN end of described timbre input chip connects the SPK end of radio interface successively by the 3rd resistance, the second electric capacity; The vdd terminal of timbre input chip is connected the output of the first filter circuit by the first inductance in power module, is also connected the OUT2 end of timbre input chip by the 5th resistance; The CE that the OUT2 end of described timbre input chip connects second source chip by the 4th resistance holds, also by the 3rd capacity earth.
5. frequency modulation anti-interference hidden earphone system according to claim 4, it is characterized in that, described FM modulation module comprises VCO chip, the tenth resistance, the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 6th electric capacity and the 7th electric capacity, the VCO_OUT end of described VCO chip connects CI end and the signal amplification module of VCO chip, the CI_1 end of VCO chip connects the CI_2 end of VCO chip by the 6th electric capacity, the vdd terminal of VCO chip connects the output of the first filter circuit by the first inductance in power module, the VCO_IN end of VCO chip connects one end of the tenth resistance by the 7th electric capacity, the other end of described tenth resistance connects one end of the 5th electric capacity in gain control module, described VCO_IN end is also successively by the 7th electric capacity, 11 grounding through resistance, the R1_TO end of VCO chip is by the 12 grounding through resistance, the R2_TO end of VCO chip is successively by the 13 resistance, 14 grounding through resistance.
6. frequency modulation anti-interference hidden earphone system according to claim 5, is characterized in that, described signal amplification module comprises amplification chip, induction coil, the 8th electric capacity, the 15 resistance and the 16 resistance; The vdd terminal of described amplification chip connects one end of the second inductance in power module, the IN-end of amplification chip connects the VCO_OUT end of VCO chip in FM modulation module successively by the 8th electric capacity, the 15 resistance, 16 resistance is connected between the IN-end of amplification chip and OUT end, and the OUT end of amplification chip is by induction coil ground connection.
7. frequency modulation anti-interference hidden earphone system according to claim 5, it is characterized in that, described FM modulation module also comprises the first adjustable resistance and the second adjustable resistance, one end of described first adjustable resistance connects one end of the 5th electric capacity in the adjustable end of the first adjustable resistance, the other end of the tenth resistance and gain control module, and the other end of the first adjustable resistance connects the VCO_IN end of VCO chip by the 7th electric capacity; One end of second adjustable resistance connects the R2_TO end of VCO chip and the adjustable end of the second adjustable resistance, and the other end of the second adjustable resistance is by the 14 grounding through resistance.
8. frequency modulation anti-interference hidden earphone system according to claim 6, it is characterized in that, described signal amplification module also comprises the 3rd adjustable resistance, one end of described 3rd adjustable resistance connects the IN-end of amplification chip and the adjustable end of the 3rd adjustable resistance, and the other end of the 3rd adjustable resistance connects the OUT end of amplification chip.
9. frequency modulation anti-interference hidden earphone system according to claim 1, it is characterized in that, also comprise the remote controller for communication control and volume, described adapter also comprises the magnetic field receiving system for communicating with remote controller, and described remote controller connects described magnetic field receiving system.
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Address after: 518000 aero electronic engineering R & D Building No. 7, No. 7, No. 701, 702, 708, 709, 710, 711 of Nanshan District hi-tech North District, Nanshan District hi-tech North District Patentee after: Shenzhen its force Industrial Co.,Ltd. Address before: 518057 Guangdong Shenzhen City, Shenzhen city Nanshan District science and Technology Park, North District Langshan Road, No. 7 China Airlines South Airlines Arts crafts emporium 7 Patentee before: Shenzhen Qili Technology Development Co.,Ltd. |
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Effective date of registration: 20171213 Address after: 518000 aero electronic engineering R & D Building No. 7, No. 701, 702, 708, 709, 710, 711 of Langshan Road, Shenzhen City, South Mountain, Guangdong Province Patentee after: SHENZHEN QILI AUDIO APPLICATION Co.,Ltd. Address before: 518000 aero electronic engineering R & D Building No. 7, No. 7, No. 701, 702, 708, 709, 710, 711 of Nanshan District hi-tech North District, Nanshan District hi-tech North District Patentee before: Shenzhen its force Industrial Co.,Ltd. |