CN110971737A - Active noise-reducing automatic telephone - Google Patents

Abstract

An active noise reduction automatic telephone comprises an input and rectification circuit, an off-hook power supply control circuit, a dual-tone frequency dialing output control circuit, a voice amplification and side-tone elimination circuit, an off-hook dialing noise interference prevention circuit, a voice handle voice output circuit, a head-wearing voice output circuit, an off-hook CPU power supply circuit, a control chip, an off-hook switching circuit, a voice input switching circuit, a voice signal transmission circuit, a DSP noise reduction module and an on-hook CPU power supply circuit, wherein the on-hook CPU power supply circuit is connected with the output end of the input and rectification circuit and the control chip; the off-hook CPU power supply circuit also supplies power for the off-hook and on-hook switching circuit, and the voice signal transmission circuit is also connected with the off-hook dialing noise interference prevention circuit. The default is a head-mounted voice input mode, and the active noise reduction and head-mounted noise reduction modes are combined, so that the noise reduction effect is good.

Description

Active noise-reducing automatic telephone

Technical Field

The invention relates to the technical field of marine telephones, in particular to an active noise reduction automatic telephone.

Background

The marine automatic telephone is used for communication between cabins on a ship in daily work and affairs, but the environment where the marine automatic telephone is located has large noise, such as sound of an engine, sound of sea waves and sound generated by working machinery on the ship, and when the telephone is used, the telephone is interfered by the noise and the sound of the other party cannot be heard. If the important instructions are overheard or overheard, the navigation safety of the ship is influenced.

In terms of noise reduction, two technical genres have evolved, one being passive noise reduction (also called physical noise reduction) and one being active noise reduction (also called active noise reduction). The technical characteristic of passive noise reduction is that various characteristics of materials are utilized to weaken noise by adopting modes of isolation, shock absorption, damping and the like for noise sources. The active noise reduction technology utilizes the characteristic of sound as a wave, and eliminates the noise by emitting reverse sound waves to offset the original sound waves and weaken or even eliminate the original sound waves. There is a need for further noise reduction in marine automotive phone applications.

Disclosure of Invention

In view of the above, the present invention provides an active noise reduction automatic telephone with good noise reduction effect, which is a default head-mounted voice input mode and combines active noise reduction and head-mounted noise reduction modes, so as to solve the above problems.

An active noise reduction automatic telephone comprises an input and rectification circuit, an off-hook power supply control circuit, a dual-tone dial output control circuit, a voice amplification and sidetone elimination circuit, an off-hook dial noise interference prevention circuit, a voice handle voice output circuit, a head-wearing voice output circuit, an off-hook CPU power supply circuit connected with the output end of the off-hook power supply control circuit, a control chip connected with the output end of the off-hook CPU power supply circuit, an off-hook switching circuit connected with the control chip, a voice input switching circuit connected with the off-hook switching circuit, a voice signal transmission circuit connected with the voice input switching circuit, a DSP noise reduction module connected with the voice signal transmission circuit and the voice amplification and sidetone elimination circuit, and an on-hook CPU power supply circuit connected with the output end of the input and rectification circuit and the control chip which are connected in sequence; the off-hook CPU power supply circuit also supplies power for the off-hook and on-hook switching circuit, and the voice signal transmission circuit is also connected with the off-hook dialing noise interference prevention circuit.

Further, the input and rectification circuit comprises a rectifier bridge DB, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a first connection CON1, and a voltage dependent resistor RV 1; the positive electrode TIP of the external power supply is connected with the first input end of the rectifier bridge DB, the negative electrode RTN of the external power supply is connected with the second input end of the rectifier bridge DB, the first output end of the rectifier bridge DB is grounded, and the second output end of the rectifier bridge DB is grounded through a first resistor R1, a second resistor R2, a third resistor R3 and a fourth capacitor C4; the first connector CON1 is connected between the positive electrode TIP and the negative electrode RTN of the external power supply; the voltage dependent resistor RV1 is connected between the positive electrode TIP and the negative electrode RTN of an external power supply; the first input end of the rectifier bridge DB is further grounded through a first capacitor C1, and the second input end is further grounded through a second capacitor C2; a first end of the third capacitor C3 is connected to a node between the first resistor R1 and the second resistor R2, and a second end is grounded; an anode of the first diode D1 is connected to a node between the third resistor R3 and the fourth capacitor C4, and is also connected to the PDETE pin of the control chip, and a cathode of the first diode D1 is connected to a first dc power supply VDD.

Further, the off-hook power supply control circuit comprises a first triode Q1, a second triode Q2, a third triode Q3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; the first triode Q1 and the second triode Q2 are both PNP type triodes, and the third triode Q3 is an NPN type triode; the output end of a rectifier bridge DB of the input and rectification circuit is connected with an emitter of a first triode Q1, the output end of the rectifier bridge DB is also connected with a base electrode of a first triode Q1 through a fourth resistor R4, and a collector electrode of the first triode Q1 is connected with an off-hook CPU power supply circuit; an emitter of the second triode Q2 is connected with a base of the first triode Q1, the base is connected with the output end of the rectifier bridge DB through a fifth resistor R5, and a collector of the second triode Q2 is connected with an off-hook CPU power supply circuit; the collector of the third triode Q3 is connected with the base of the second triode Q2 through a sixth resistor R6, and the base is connected with the DP pin of the control chip through a seventh resistor R7.

Further, the off-hook CPU power supply circuit includes a fourth triode Q4, an eighth resistor R8, a ninth resistor R9, a fifth capacitor C5, a first regulator DZ1, and a second regulator DZ 2; the fourth triode Q4 is an NPN type triode; the collector of the fourth triode Q4 is connected with the collector of the first triode Q1 and the collector of the second triode Q2; the base electrode of the fourth triode Q4 is connected with the collector electrode of the first triode Q1 through an eighth resistor R8, the emitter electrode of the fourth triode Q4 is connected with the first end of a ninth resistor R9, and the second end of the ninth resistor R9 is a first direct current power supply VDD; the base electrode of the fourth triode Q4 is grounded through a fifth capacitor C5 and is connected with the cathode of a first voltage-regulator tube DZ1, and the anode of the first voltage-regulator tube DZ1 is grounded; the anode of the second voltage regulator DZ2 is grounded, and the cathode is connected to the collector of the first transistor Q1.

Further, the dual tone frequency dialing output control circuit comprises a fifth triode Q5, a tenth resistor R10, an eleventh resistor R11, a sixth capacitor C6, a seventh capacitor C7 and an eighth capacitor C8; the fifth triode Q5 is an NPN type triode; a collector of the fifth triode Q5 is connected with a collector of the first triode Q1, a base of the fifth triode Q5 is connected with a DTMF pin of the control chip through an eleventh resistor R11, and an emitter of the fifth triode Q5 is grounded through a tenth resistor R10; the collector of the fifth triode Q5 is also grounded through a sixth capacitor C6; the base of the fifth transistor Q5 is connected to the DTMF pin through a seventh capacitor C7 and also to ground through an eighth capacitor C8.

Further, the voice amplifying and side-tone canceling circuit comprises a sixth triode Q6, a seventh triode Q7, a second diode D2, a third diode D3, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12 and a thirteenth capacitor C13; the sixth triode Q6 is an NPN type triode, and the seventh triode Q7 is a PNP type triode; a collector of the fifth triode Q5 is connected with an emitter of the seventh triode Q7, a base of the seventh triode Q7 is connected with a collector of the fifth triode Q5 through a twelfth resistor R12, the collector is connected with a first end of a twelfth capacitor C12 through a thirteenth resistor R23, and a second end of the twelfth capacitor C12 is grounded; a collector of the sixth triode Q6 is connected with a base of the fifth triode Q5, the base is connected with a collector of the fifth triode Q5 through a fourteenth resistor R14 and a thirteenth resistor R13, and an emitter is connected with a first end of a twelfth capacitor C12 through a twelfth resistor R22; a first end of the ninth capacitor C9 is connected to a node between the fourteenth resistor R14 and the thirteenth resistor R13, and a second end is grounded; a first end of the tenth capacitor C10 is connected with the base of the sixth triode Q6, and a second end is grounded; the base electrode of the sixth triode Q6 is also connected with the first end of a twelfth capacitor C12 through a twenty-first resistor R21, and the thirteenth capacitor C13 is connected in parallel with two ends of the twenty-first resistor R21; the twentieth resistor R20 is connected with the emitter of the sixth triode Q6 and the collector of the seventh triode Q7; the anode of the second diode D2 is connected to the collector of the seventh transistor Q7 through a nineteenth resistor R19, and the cathode is connected to the emitter of the sixth transistor Q6; an emitter of the seventh triode Q7 is connected with a collector of the seventh triode Q7 through a fifteenth resistor R15, a sixteenth resistor R16 and an eighteenth resistor R18; an eleventh capacitor C11 is connected in parallel with two ends of the fifteenth resistor R15; a first end of the seventeenth resistor R17 is connected to a node between the sixteenth resistor R16 and the eighteenth resistor R18, a second end is connected to an anode of the third diode D3, and a cathode of the third diode D3 is connected to a first end of the twelfth capacitor C12.

Further, the off-hook dialing noise interference prevention circuit comprises a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a third voltage regulator tube DZ3, a fourteenth capacitor C14, a fifteenth capacitor C15, a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18, a twenty-fourth resistor R24 and a twenty-fifth resistor R25; a node between the sixteenth resistor R16 and the eighteenth resistor R18 is connected with a first end of a fourteenth capacitor C14, a second end of the fourteenth capacitor C14 is connected with an anode of a fourth diode D4 through a fifteenth capacitor C15 and a twenty-fourth resistor R24, and a cathode of the fourth diode D4 is connected with a MUTE pin of the control chip; the second terminal of the fourteenth capacitor C14 is further connected to ground through the sixteenth capacitor C16; the seventeenth capacitor C17 is connected between the first end of the fourteenth capacitor C14 and the cathode of the third diode D3; the anode of the third voltage regulator tube DZ3 is grounded, and the cathode is connected with the cathode of a third diode D3; an anode of the fifth diode D5 is connected to a cathode of the third diode D3, and a cathode thereof is connected to an anode of the sixth diode D6; the cathode of the sixth diode D6 is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the anode of the eighth diode D8; the cathode of the eighth diode D8 is grounded; the cathode of the third diode D3 is also connected to the MUTE pin of the control chip through a twenty-fifth resistor R25; the eighteenth capacitor C18 has a first terminal connected to ground and a second terminal connected to the microphone voice output circuit.

Further, the first end of the DSP noise reduction module is connected to the base of a sixth triode Q6; the voice signal transmission circuit comprises an eighth triode Q8, a ninth diode D9, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a twenty-ninth resistor R29, a nineteenth capacitor C19, a twentieth capacitor C20, a twenty-first capacitor C21 and a twenty-second capacitor C22; the eighth triode Q8 is an NPN type triode; the anode of the ninth diode D9 is connected to the MUTE pin of the control chip and is also grounded through a twelfth capacitor C22; the cathode of the ninth diode D9 is connected to the collector of the eighth triode Q8 through a twenty-sixth resistor R26, and is further connected to the second end of the DSP noise reduction module through a twenty-seventh resistor R27 and a nineteenth capacitor C19; the base electrode of the eighth triode Q8 is connected to the node between the twenty-seventh resistor R27 and the twenty-sixth resistor R26 through the twenty-eighth resistor R28, and is also grounded through the twenty-first capacitor C21; the emitter of the eighth triode Q8 is grounded; the base of the eighth transistor Q8 is further connected to the first terminal of the twentieth capacitor C20, and the second terminal of the twentieth capacitor C20 is grounded through the twenty-ninth resistor R29.

Further, the on-HOOK switching circuit comprises a reed pipe plate HOOK, a first field effect tube Q14, a second field effect tube Q15, a forty-first resistor R41 and a forty-second resistor R42; the reed pipe plate HOOK is provided with a first reed pipe and a second reed pipe, wherein the first reed pipe is provided with a first normally open end HOOK1 and a first normally closed end HOOK2, and the second reed pipe is provided with a second normally open end HFMI and a second normally closed end HSMI; the first end of the first reed switch is connected with a first direct current power supply VDD, the second end of the first reed switch can be selectively connected with a first normally-open end HOOK1 and a first normally-closed end HOOK2, and the first normally-open end HOOK1 is grounded through a fourth twelve resistor R42 and is simultaneously connected with the grid electrode of a first field effect transistor Q14; the drain electrode of the first field effect transistor Q14 is connected with the HKS pin of the control chip, and the source electrode is grounded; the first normally-off terminal HOOK2 is grounded through a fourth eleventh resistor R41 and is connected with the gate of the second fet Q15; the drain and source of the second fet Q15 are both grounded.

Further, the voice input switching circuit comprises a switch SW, a handle microphone MIC and a head microphone HSMT; the first normally closed end HOOK2 is connected with a microphone MIC, and the second normally closed end HSMI is connected with a headset microphone HSMT; the switch SW is disposed between the first reed switch and the second reed switch, a first end of the switch SW is connected to a second end of the twentieth capacitor C20, and a second end of the switch SW is selectively connected to the first normally-closed end HOOK2 or the second normally-closed end HSMI; the first normally closed end HOOK2 is connected with the first end of the microphone MIC, and the second end of the microphone MIC is grounded; the second normally-closed terminal HSMI is connected to the first terminal of the headset microphone HSMT, and the second terminal of the headset microphone HSMT is grounded.

Compared with the prior art, the active noise reduction automatic telephone comprises an input and rectifying circuit, an off-hook power supply control circuit, a dual-tone dialing output control circuit, a voice amplification and side-tone elimination circuit, an off-hook dialing noise interference prevention circuit, a voice handle voice output circuit and a head-wearing voice output circuit which are connected in sequence, the off-hook CPU power supply circuit is connected with the output end of the off-hook power supply control circuit, the control chip is connected with the output end of the off-hook CPU power supply circuit, the off-hook switching circuit is connected with the control chip, the voice input switching circuit is connected with the off-hook switching circuit, the voice signal transmission circuit is connected with the voice input switching circuit, the DSP noise reduction module is connected with the voice signal transmission circuit and the voice amplification and side tone elimination circuit, and the off-hook CPU power supply circuit is connected with the output end of the input and rectification circuit and the control chip; the off-hook CPU power supply circuit also supplies power for the off-hook and on-hook switching circuit, and the voice signal transmission circuit is also connected with the off-hook dialing noise interference prevention circuit. The default is a head-mounted voice input mode, and the active noise reduction and head-mounted noise reduction modes are combined, so that the noise reduction effect is good.

Drawings

Embodiments of the invention are described below with reference to the accompanying drawings, in which:

fig. 1 is a block diagram of an active noise reduction automatic telephone provided by the present invention.

Fig. 2 is a circuit diagram of the input and rectifying circuit in fig. 1.

Fig. 3 is a circuit schematic diagram of an off-hook power supply control circuit, an off-hook CPU power supply circuit and a dual tone dial output control circuit in fig. 1.

Fig. 4 is a circuit diagram of the voice amplifying and side-tone canceling circuit and the DSP noise reduction module in fig. 1.

Fig. 5 is a circuit diagram of the off-hook dialing noise interference prevention circuit and the voice signal transmission circuit in fig. 1.

Fig. 6 is a circuit diagram of the voice output circuit of fig. 1.

Fig. 7 is a circuit schematic diagram of the head-mounted voice output circuit in fig. 1.

Fig. 8 is a circuit schematic diagram of the hook switching circuit and the voice input switching circuit in fig. 1.

Fig. 9 is a circuit schematic diagram of the on-hook CPU power supply circuit of fig. 1.

Fig. 10 is a schematic diagram of the reed pipe plate and the control chip in fig. 1.

Detailed Description

Specific embodiments of the present invention will be described in further detail below based on the drawings. It should be understood that the description herein of embodiments of the invention is not intended to limit the scope of the invention.

Referring to fig. 1, the active noise reduction automatic telephone of the present invention comprises an input and rectification circuit 10, an off-hook power supply control circuit 20, a dual tone dialing output control circuit 30, a voice amplification and side tone cancellation circuit 40, an off-hook dialing noise interference prevention circuit 50, a handset voice output circuit 60, and a headset voice output circuit 70 connected in sequence, and an off-hook CPU power supply circuit 81 connected to the output terminal of the off-hook power supply control circuit 20, a control chip 82 connected to the output terminal of the off-hook CPU power supply circuit 81, an on-hook switching circuit 83 connected to the control chip 82, a voice input switching circuit 93 connected to the on-hook switching circuit 83, a voice signal transfer circuit 92 connected to the voice input switching circuit 93, a DSP noise reduction module 91 connecting the voice signal transfer circuit 92 to the voice amplification and side-tone cancellation circuit 40, and an on-hook CPU power supply circuit 84 connected to the output terminal of the input and rectification circuit 10.

The off-hook CPU power supply circuit 81 also supplies power to the off-hook switching circuit 83, and the voice signal transfer circuit 92 is also connected to the off-hook dialing noise interference prevention circuit 50.

Referring to fig. 2, the input and rectifying circuit 10 includes a rectifying bridge DB, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a first connector CON1, and a varistor RV 1. Wherein, the triangular grounding and the grounding of the three-section line are conducted under the condition of picking up the microphone handle; under the condition of using the headset, the triangular grounding is disconnected with the grounding of the three-section wire, and the headset is connected with the circuit of the microphone handle in series, so that higher current can be provided for related circuits of the headset, and higher sound signals can be output.

The positive electrode TIP of the external power supply is connected with the first input end of the rectifier bridge DB, the negative electrode RTN of the external power supply is connected with the second input end of the rectifier bridge DB, the first output end of the rectifier bridge DB is grounded, and the second output end a is grounded through the first resistor R1, the second resistor R2, the third resistor R3 and the fourth capacitor C4.

The first connector CON1 is connected between the positive TIP and the negative RTN of the external power source, and the first connector CON1 is connected to the external switch, so as to provide the working power source and transmit the voice signal for the active noise reduction automatic telephone provided by the present invention.

The voltage dependent resistor RV1 is connected between the positive electrode TIP and the negative electrode RTN of the external power supply. The voltage dependent resistor RV1 protects against excessive voltage.

The first input terminal of the rectifier bridge DB is further grounded through a first capacitor C1, and the second input terminal is further grounded through a second capacitor C2.

The third capacitor C3 has a first end connected to the node between the first resistor R1 and the second resistor R2, and a second end connected to ground.

An anode of the first diode D1 is connected to a node between the third resistor R3 and the fourth capacitor C4, and is also connected to a PDETE pin of the control chip 82, and a cathode of the first diode D1 is connected to a first dc power supply VDD. The PDETE pin is a parallel machine signal detection input.

Referring to fig. 3, the off-hook power supply control circuit 20 includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7.

The first transistor Q1 and the second transistor Q2 are both PNP transistors, and the third transistor Q3 is an NPN transistor.

A second output terminal a of the rectifier bridge DB of the input and rectifying circuit 10 is connected to an emitter of the first transistor Q1, and is also connected to a base of the first transistor Q1 through a fourth resistor R4, and a collector of the first transistor Q1 is connected to the off-hook CPU power supply circuit 81. The output voltage at the second output terminal a of the rectifier bridge DB is 48V.

The emitter of the second triode Q2 is connected to the base of the first triode Q1, the base is connected to the second output terminal a of the rectifier bridge DB through a fifth resistor R5, and the collector of the second triode Q2 is connected to the off-hook CPU power supply circuit 81.

The collector of the third transistor Q3 is connected to the base of the second transistor Q2 through a sixth resistor R6, and the base is connected to the DP pin of the control chip 82 through a seventh resistor R7. And the DP pin is a variable signal pin of the on-hook and off-hook and is used for controlling the switching of an on-hook and off-hook circuit.

When the DP pin is high, the third transistor Q3 is turned on, the second transistor Q2 is turned on, the first transistor Q1 is turned on, the off-hook CPU power supply circuit 81 and subsequent circuits are all used as loads, and the voltage is pulled down from 48V to about 7V (actually lower than 7V); when the DP pin is low, the third transistor Q3 is turned off, the second transistor Q2 is turned off, the first transistor Q1 is turned off, and the off-hook CPU power supply circuit 81 and subsequent circuits are all turned off.

The off-hook CPU power supply circuit 81 includes a fourth transistor Q4, an eighth resistor R8, a ninth resistor R9, a fifth capacitor C5, a first regulator DZ1, and a second regulator DZ 2. The fourth transistor Q4 is an NPN transistor. The action of the fourth transistor Q4 expands the current.

The collector of the fourth transistor Q4 is connected to both the collector of the first transistor Q1 and the collector of the second transistor Q2. The base of the fourth triode Q4 is connected to the collector of the first triode Q1 through an eighth resistor R8, the emitter of the fourth triode Q4 is connected to the first end of a ninth resistor R9, and the second end of the ninth resistor R9 is the first dc power supply VDD. The base of the fourth triode Q4 is also grounded through a fifth capacitor C5 and connected with the cathode of the first voltage regulator tube DZ1, the anode of the first voltage regulator tube DZ1 is grounded, the anode of the second voltage regulator tube DZ2 is grounded, and the cathode is connected with the collector of the first triode Q1.

The dual tone dial output control circuit 30 includes a fifth transistor Q5, a tenth resistor R10, an eleventh resistor R11, a sixth capacitor C6, a seventh capacitor C7, and an eighth capacitor C8. The fifth transistor Q5 is an NPN transistor.

The collector b of the fifth transistor Q5 is connected to the collector of the first transistor Q1, the base is connected to the DTMF pin of the control chip 82 through an eleventh resistor R11, and the emitter is grounded through a tenth resistor R10. The collector b of the fifth transistor Q5 is also connected to ground through a sixth capacitor C6. The base of the fifth transistor Q5 is connected to the DTMF pin through a seventh capacitor C7 and also to ground through an eighth capacitor C8.

The DTMF pin is a dual Tone Multi-frequency (DTMF) pin, which is composed of a high frequency group and a low frequency group, each of the high frequency group and the low frequency group includes 4 frequencies. A high frequency signal and a low frequency signal are superimposed to form a combined signal representing a number. The DTMF signal has 16 codes, and the corresponding telephone set can be selectively called by the DTMF signal.

The dual tone dialing output control circuit 30 is used for controlling the output of the key signals, and the dual tone dialing is that the keys generate signals with two frequencies to represent the keys, which is different from pulse dialing. Can be used for displaying the number of the incoming call.

Referring to fig. 4, the voice amplifying and side-tone canceling circuit 40 includes a sixth transistor Q6, a seventh transistor Q7, a second diode D2, a third diode D3, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12, and a thirteenth capacitor C13. The sixth transistor Q6 is an NPN type transistor, and the seventh transistor Q7 is a PNP type transistor.

A collector b of the fifth triode Q5 is connected with an emitter of the seventh triode Q7, a base of the seventh triode Q7 is connected with a collector b of the fifth triode Q5 through a twelfth resistor R12, a collector is connected with a first end of a twelfth capacitor C12 through a thirteenth resistor R23, and a second end of the twelfth capacitor C12 is grounded.

The collector of the sixth triode Q6 is connected to the base of the fifth triode Q5, the base is connected to the collector b of the fifth triode Q5 through the fourteenth resistor R14 and the thirteenth resistor R13, and the emitter is connected to the first end of the twelfth capacitor C12 through the twelfth resistor R22.

The ninth capacitor C9 has a first terminal connected to the node between the fourteenth resistor R14 and the thirteenth resistor R13, and a second terminal connected to ground.

A first end of the tenth capacitor C10 is connected to the base of the sixth transistor Q6, and a second end is grounded. The base of the sixth triode Q6 is further connected to the first end of the twelfth capacitor C12 through the twenty-first resistor R21, and the thirteenth capacitor C13 is connected in parallel to two ends of the twenty-first resistor R21.

The twentieth resistor R20 connects the emitter of the sixth transistor Q6 and the collector of the seventh transistor Q7.

The anode of the second diode D2 is connected to the collector of the seventh transistor Q7 through a nineteenth resistor R19, and the cathode is connected to the emitter of the sixth transistor Q6.

An emitter of the seventh transistor Q7 is connected to a collector of the seventh transistor Q7 through a fifteenth resistor R15, a sixteenth resistor R16 and an eighteenth resistor R18. An eleventh capacitor C11 is connected in parallel with two ends of the fifteenth resistor R15.

A first end of the seventeenth resistor R17 is connected to the node C between the sixteenth resistor R16 and the eighteenth resistor R18, a second end is connected to the anode of the third diode D3, and the cathode D of the third diode D3 is connected to the first end of the twelfth capacitor C12.

The first terminal of the DSP noise reduction module 91 is connected to the base of the sixth transistor Q6. The second end e of the DSP noise reduction module 91 is connected to the voice signal transmission circuit 92. The DSP noise reduction module 91 adopts a PI-36 digital DSP remote picking noise reduction module, adopts a dual-core DSP chip with a unique high-efficiency noise reduction algorithm, and has effects on both steady-state noise and unsteady-state noise. The PI-36 digital DSP remote picking noise reduction module is in a self-adaptive working mode, has AGC homoenergetic while inhibiting environmental noise, and can meet the picking range of 30cm-700 cm. The sampling frequency of a main chip is 16KHZ, the working current of a conventional mode is 20mA, and the noise reduction index is 30-36 db. The method can effectively solve the problem of environmental background noise interference in various voice calls and recording pickup, and obtains the voice signals with higher signal-to-noise ratio.

The emitter of the sixth transistor Q6 and the collector of the seventh transistor Q7 generate electric signals with opposite phases, which cancel each other out, and the twentieth resistor R20 adjusts the intensity of the electric signal with opposite phases to cancel the side noise.

Referring to fig. 5, the off-hook dialing noise interference preventing circuit 50 includes a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a third regulator DZ3, a fourteenth capacitor C14, a fifteenth capacitor C15, a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18, a twenty-fourth resistor R24, and a twenty-fifth resistor R25.

A node C between the sixteenth resistor R16 and the eighteenth resistor R18 is connected to a first end of the fourteenth capacitor C14, a second end f of the fourteenth capacitor C14 is connected to an anode of the fourth diode D4 through the fifteenth capacitor C15 and the twenty-fourth resistor R24, and a cathode of the fourth diode D4 is connected to the MUTE pin of the control chip 82. The second terminal f of the fourteenth capacitor C14 is also connected to ground through the sixteenth capacitor C16.

The seventeenth capacitor C17 is connected between the first end of the fourteenth capacitor C14 and the cathode D of the third diode D3. The anode of the third regulator DZ3 is grounded, and the cathode is connected to the cathode D of the third diode D3.

The anode of the fifth diode D5 is connected to the cathode D of the third diode D3, and the cathode is connected to the anode of the sixth diode D6; the cathode of the sixth diode D6 is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the anode of the eighth diode D8; the cathode of the eighth diode D8 is grounded.

The cathode D of the third diode D3 is also connected to the MUTE pin of the control chip 82 through a twenty-fifth resistor R25.

The eighteenth capacitor C18 has a first terminal connected to ground and a second terminal g connected to the microphone voice output circuit 60.

The voice signal transmission circuit 92 includes an eighth transistor Q8, a ninth diode D9, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a twenty-ninth resistor R29, a nineteenth capacitor C19, a twentieth capacitor C20, a twenty-first capacitor C21, and a twenty-second capacitor C22. The eighth transistor Q8 is an NPN transistor.

The anode of the ninth diode D9 is connected to the MUTE pin of the control chip 82 and is also connected to ground through a twelfth capacitor C22. The cathode of the ninth diode D9 is connected to the collector of the eighth transistor Q8 through a twenty-sixth resistor R26, and is further connected to the second end e of the DSP noise reduction module 91 through a twenty-seventh resistor R27 and a nineteenth capacitor C19.

The base of the eighth triode Q8 is connected to the node between the twenty-seventh resistor R27 and the twenty-sixth resistor R26 through the twenty-eighth resistor R28, and also to ground through the twenty-first capacitor C21.

The emitter of the eighth transistor Q8 is grounded.

The base of the eighth transistor Q8 is further connected to the first terminal of the twentieth capacitor C20, and the second terminal h of the twentieth capacitor C20 is grounded through the twenty-ninth resistor R29.

The MUTE pin is a MUTE pin, when dialing, the potential of MUTE is pulled down, the voltage of the eighth triode Q8 is insufficient, so that external noise cannot be transmitted, and the interference of the external noise to a dialing audio frequency is shielded.

The voice signal generated by the moving coil of the microphone or the headset is transmitted through the eighth transistor Q8 to the second end e of the DSP noise reduction module 91.

Referring to fig. 6, the speech output circuit 60 includes a ninth transistor Q9, a thirteenth transistor Q10, a speech speaker REC1, a thirtieth resistor R30, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35, a twenty-third capacitor C23, and a twenty-fourth capacitor C24. The ninth triode Q9 and the thirteenth diode Q10 are both NPN-type triodes.

The base of the ninth triode Q9 is connected to the second terminal f of the fourteenth capacitor C14, the collector is connected to the second terminal g of the eighteenth capacitor C18 through the thirtieth resistor R30, and the emitter is grounded through the thirty-first resistor R31.

The base of the thirteenth diode Q10 is connected to the collector of the ninth transistor Q9, the collector is connected to the second end g of the eighteenth capacitor C18 through a thirteenth resistor R33, and the emitter is grounded through a fifteenth resistor R35 and connected to the base of the ninth transistor Q9 through a fourteenth resistor R34. The twenty-fourth capacitor C24 is connected in parallel across the thirty-fifth resistor R35. The first end of the handle loudspeaker REC1 is connected to the second end g of the eighteenth capacitor C18, and the second end i is connected to the emitter of the ninth transistor Q9 via a third dodeca-resistor R32. A twenty-third capacitor C23 is connected in parallel between the first terminal and the second terminal i of the handle loudspeaker REC 1.

Referring to fig. 7, the head-mounted voice output circuit 70 includes an eleventh triode Q11, a twelfth triode Q12, a thirteenth triode Q13, a fourth voltage regulator DZ4, a twelfth diode D10, an eleventh diode D11, a head-mounted speaker REC2, a thirty-sixth resistor R36, a thirty-seventh resistor R37, a thirty-eighth resistor R38, a thirty-ninth resistor R39, a forty resistor R40, a twenty-fifth capacitor C25, a twenty-sixth capacitor C26, a twenty-seventh capacitor C27, a twenty-eighth capacitor C28, a twenty-ninth capacitor C29, a thirty capacitor C30, a thirty-eleventh capacitor C31, and a thirty-second capacitor C32. The eleventh transistor Q11 and the thirteenth transistor Q13 are NPN transistors, and the twelfth transistor Q12 is a PNP transistor.

A first end of the twenty-fifth capacitor C25 is connected to the second end i of the handle speaker REC1 via a sixteenth resistor R36, and a second end is connected to the base of the eleventh transistor Q11. The collector of the eleventh triode Q11 is connected with the base of the twelfth triode Q12, and the emitter is grounded. The base of the eleventh transistor Q11 is also connected to ground through a twenty-sixth capacitor C26.

An emitter of the twelfth triode Q12 is connected with the second end of the twenty-fifth capacitor C25 through a seventeenth resistor R37, and a collector is grounded. The base of the twelfth transistor Q12 is also connected to ground through a twenty-seventh capacitor C27. The twenty-ninth capacitor C29 is connected in parallel across the thirty-seventh resistor R37.

The first terminal of the head-mounted speaker REC2 is connected to the emitter of the twelfth triode Q12 through a second eighteen-capacitor C28, and the second terminal is grounded.

An emitter of the thirteenth triode Q13 is connected to an emitter of the twelfth triode Q12, a base of the thirteenth triode Q13 is connected to a first end of a thirty-first capacitor C30 through a thirty-eighth resistor R38, and a second end of the thirty-first capacitor C30 is connected to an emitter of the twelfth triode Q12. The collector of the thirteenth triode Q13 is connected to the first terminal of the thirtieth capacitor C30 through a thirty-ninth resistor R39.

The anode of the twelfth diode D10 is connected with the base of the thirteenth triode Q13, and the cathode is connected with the anode of the eleventh diode D11; the cathode of the eleventh diode D11 is connected to the base of the twelfth transistor Q12.

The collector of the thirteenth triode Q13 is grounded, and is further grounded through a fortieth resistor R40, a thirty-first capacitor C31 and a thirty-second capacitor C32, respectively, and is further connected with the cathode of the fourth voltage regulator DZ4, and the anode of the fourth voltage regulator DZ4 is grounded. These elements connected to ground filter and stabilize the voltage between two grounds when using the headset.

Referring to fig. 8, the HOOK switching circuit 83 includes a reed switch board HOOK, a first fet Q14, a second fet Q15, a forty-first resistor R41, and a forty-second resistor R42.

Referring to fig. 10, the reed pipe plate HOOK has a first reed pipe having a first normally open end HOOK1 and a first normally closed end HOOK2, and a second reed pipe having a second normally open end HFMI and a second normally closed end HSMI. The first normally closed terminal HOOK2 is connected to the handset microphone MIC, and the second normally closed terminal HSMI is connected to the headset microphone HSMT.

The first reed switch has a first terminal connected to a first dc power source VDD, and a second terminal selectively connected to the first normally open terminal HOOK1 and the first normally closed terminal HOOK 2.

The first normally-open terminal HOOK1 is grounded through a fourth twelve-resistor R42 and is connected with the gate of the first field-effect transistor Q14; the drain of the first fet Q14 is connected to the HKS pin of the controller chip 82, and the source is grounded. The HKS pin is a starting signal input pin, when the voice handle is picked up, the first reed switch jumps to a first normally closed end HOOK2, the first field effect transistor Q14 is cut off, the HKS pin is pulled high, and therefore an off-HOOK signal is given to the CPU.

The first normally-off terminal HOOK2 is grounded through a fourth eleventh resistor R41 and is connected with the gate of the second fet Q15; the drain and source of the second fet Q15 are both grounded.

The voice input switching circuit 93 includes a switch SW, a stem microphone MIC, and a head microphone HSMT.

The switch SW is arranged between the first reed switch and the second reed switch and used for realizing the simultaneous action of the first reed switch and the second reed switch. When the first reed pipe is connected with the first normally closed end HOOK2, the second reed pipe is connected with the second normally open end HFMI; the second reed switch is connected to the second normally closed end HSMI while the first reed switch is connected to the first normally open end HOOK 1.

The first terminal of the switch SW is connected to the second terminal h of the twentieth capacitor C20, and the second terminal thereof can be selectively connected to the first normally-off terminal HOOK2 or the second normally-off terminal HSMI. The first normally closed terminal HOOK2 is connected to a first terminal of the microphone MIC, and a second terminal of the microphone MIC is connected to ground. The second normally-closed terminal HSMI is connected to the first terminal of the headset microphone HSMT, and the second terminal of the headset microphone HSMT is grounded.

The headphone speaker REC2 and the headphone microphone HSMT are provided on the headphone.

A magnet is arranged in the handle and is used for adsorbing two reed pipes on the reed pipe plate when the handle is electrified, so that the jumping of the first reed pipe and the second reed pipe is synchronous. When off-HOOK occurs, the first reed switch jumps to a first normally closed end HOOK2, and a HKS pin provides an off-HOOK signal; at the same time, the second reed switch jumps to the second normally open end HFMI, at which time the stem microphone MIC is active and the headset microphone HSMT is inactive. On the contrary, the first reed pipe is connected with the first normally open end HOOK1, and the second reed pipe is connected with the second normally closed end HSMI, at this time, the headset microphone HSMT is in an operating state.

Referring to fig. 9, the on-hook CPU power supply circuit 84 includes a fourteenth triode Q16, a fifteenth triode Q17, a sixteenth triode Q18, a seventeenth triode Q19, a twelfth diode D12, a forty-third resistor R43, a forty-fourth resistor R44, a forty-fifth resistor R45, a forty-sixth resistor R46, a forty-seventh resistor R47, a forty-eighth resistor R48, a forty-ninth resistor R49, a thirty-third capacitor C33, a thirty-fourth capacitor C34, and a thirty-fifth capacitor C35. The fourteenth triode Q16 is a PNP triode, and the fifteenth triode Q17, the sixteenth triode Q18 and the seventeenth triode Q19 are NPN triodes.

The cathode of the twelfth diode D12 is connected to the first dc power supply VDD, and is grounded through the thirteenth capacitor C33, and the anode is connected to the collector of the fourteenth triode Q16; an emitter of the fourteenth triode Q16 is connected to the second output terminal a of the rectifier bridge DB through a seventeenth resistor R47, and a base thereof is connected to a forty-seventh resistor R47 through a forty-thirteen resistor R43. The collector of the fifteenth triode Q17 is connected to the base of the fourteenth triode Q16, the emitter is connected to the collector of the fourteenth triode Q16, and the base is grounded through the thirty-fourth capacitor C34. The emitter of the fifteenth triode Q17 is also connected to ground through a fourteenth resistor R44 and a forty-fifth resistor R45.

The base of the sixteenth triode Q18 is connected to the node between the forty-fourth resistor R44 and the forty-fifth resistor R45, the collector is connected to the forty-seventh resistor R47 through the forty-sixteenth resistor R46, and the emitter is grounded.

The collector of the seventeenth triode Q19 is connected with the second output end a of the rectifier bridge DB through a forty-eight resistor R48, the base is connected with the pin DTTMF0 of the control chip 82 through a forty-nine resistor R49, the base is also grounded through a thirty-five capacitor C35, and the emitter is grounded. The DTTMF0 pin is reserved for dual tone multi-frequency input identification.

When the telephone is hung up, only the power supply of the control chip 82 and a small number of components is needed to be kept, the power is stolen on the signal line through the hanging-up CPU power supply circuit 84 to keep the working state, and the normal work of other telephones is not influenced; when the phone is off-hook (including the handset mode and the headset mode), the power consumption is relatively large, and the off-hook power supply control circuit 20 is required to supply power specially.

Referring to fig. 10, the reed switch board HOOK has a first normally open end HOOK1, a first normally closed end HOOK2, a voice output end Sound, a power supply end VDD, a second normally open end HFMI, and a second normally closed end HSMI.

The control chip 82 has a model number D63040TP, and has a power supply terminal VDD, a ground terminal GND, a PDETE pin, a DP pin, a DTME pin, a MUTE pin, a HKS pin, a DTTMF0 pin, and the like.

Compared with the prior art, the active noise reduction automatic telephone of the invention comprises an input and rectification circuit 10, an off-hook power supply control circuit 20, a dual-tone dialing output control circuit 30, a voice amplification and side-tone elimination circuit 40, an off-hook dialing noise interference prevention circuit 50, a voice handle output circuit 60 and a head-wearing voice output circuit 70 which are connected in sequence, an off-hook CPU power supply circuit 81 connected to the output terminal of the off-hook power supply control circuit 20, a control chip 82 connected to the output terminal of the off-hook CPU power supply circuit 81, an on-hook switching circuit 83 connected to the control chip 82, a voice input switching circuit 93 connected to the on-hook switching circuit 83, a voice signal transfer circuit 92 connected to the voice input switching circuit 93, a DSP noise reduction module 91 connecting the voice signal transfer circuit 92 to the voice amplification and side-tone cancellation circuit 40, and an on-hook CPU power supply circuit 84 connected to the output terminal of the input and rectification circuit 10; the off-hook CPU power supply circuit 81 also supplies power to the off-hook switching circuit 83, and the voice signal transfer circuit 92 is also connected to the off-hook dialing noise interference prevention circuit 50. The default is a head-mounted voice input mode, and the active noise reduction and head-mounted noise reduction modes are combined, so that the noise reduction effect is good.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the present invention, and any modifications, equivalents or improvements that are within the spirit of the present invention are intended to be covered by the following claims.

Claims (10)

1. An active noise reducing automatic telephone, characterized by: the voice dialing device comprises an input and rectifying circuit, an off-hook power supply control circuit, a dual-tone dialing output control circuit, a voice amplifying and side tone eliminating circuit, an off-hook dialing noise interference preventing circuit, a voice handle voice output circuit, a head-wearing voice output circuit, an off-hook CPU power supply circuit connected with the output end of the off-hook power supply control circuit, a control chip connected with the output end of the off-hook CPU power supply circuit, an off-hook switching circuit connected with the control chip, a voice input switching circuit connected with the off-hook switching circuit, a voice signal transmission circuit connected with the voice input switching circuit, a DSP noise reduction module connected with the voice signal transmission circuit and the voice amplifying and side tone eliminating circuit, and an on-hook CPU power supply circuit connected with the output end of the input and rectifying circuit and the control chip which are connected in sequence; the off-hook CPU power supply circuit also supplies power for the off-hook and on-hook switching circuit, and the voice signal transmission circuit is also connected with the off-hook dialing noise interference prevention circuit.

2. The active noise reduction automatic telephone of claim 1, wherein: the input and rectification circuit comprises a rectifier bridge DB, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a first connection CON1 and a piezoresistor RV 1; the positive electrode TIP of the external power supply is connected with the first input end of the rectifier bridge DB, the negative electrode RTN of the external power supply is connected with the second input end of the rectifier bridge DB, the first output end of the rectifier bridge DB is grounded, and the second output end of the rectifier bridge DB is grounded through a first resistor R1, a second resistor R2, a third resistor R3 and a fourth capacitor C4; the first connector CON1 is connected between the positive electrode TIP and the negative electrode RTN of the external power supply; the voltage dependent resistor RV1 is connected between the positive electrode TIP and the negative electrode RTN of an external power supply; the first input end of the rectifier bridge DB is further grounded through a first capacitor C1, and the second input end is further grounded through a second capacitor C2; a first end of the third capacitor C3 is connected to a node between the first resistor R1 and the second resistor R2, and a second end is grounded; an anode of the first diode D1 is connected to a node between the third resistor R3 and the fourth capacitor C4, and is also connected to the PDETE pin of the control chip, and a cathode of the first diode D1 is connected to a first dc power supply VDD.

3. The active noise reduction automatic telephone of claim 2, wherein: the off-hook power supply control circuit comprises a first triode Q1, a second triode Q2, a third triode Q3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; the first triode Q1 and the second triode Q2 are both PNP type triodes, and the third triode Q3 is an NPN type triode; the output end of a rectifier bridge DB of the input and rectification circuit is connected with an emitter of a first triode Q1, the output end of the rectifier bridge DB is also connected with a base electrode of a first triode Q1 through a fourth resistor R4, and a collector electrode of the first triode Q1 is connected with an off-hook CPU power supply circuit; an emitter of the second triode Q2 is connected with a base of the first triode Q1, the base is connected with the output end of the rectifier bridge DB through a fifth resistor R5, and a collector of the second triode Q2 is connected with an off-hook CPU power supply circuit; the collector of the third triode Q3 is connected with the base of the second triode Q2 through a sixth resistor R6, and the base is connected with the DP pin of the control chip through a seventh resistor R7.

4. An active noise reducing automatic telephone as claimed in claim 3 wherein: the off-hook CPU power supply circuit comprises a fourth triode Q4, an eighth resistor R8, a ninth resistor R9, a fifth capacitor C5, a first voltage-regulator tube DZ1 and a second voltage-regulator tube DZ 2; the fourth triode Q4 is an NPN type triode; the collector of the fourth triode Q4 is connected with the collector of the first triode Q1 and the collector of the second triode Q2; the base electrode of the fourth triode Q4 is connected with the collector electrode of the first triode Q1 through an eighth resistor R8, the emitter electrode of the fourth triode Q4 is connected with the first end of a ninth resistor R9, and the second end of the ninth resistor R9 is a first direct current power supply VDD; the base electrode of the fourth triode Q4 is grounded through a fifth capacitor C5 and is connected with the cathode of a first voltage-regulator tube DZ1, and the anode of the first voltage-regulator tube DZ1 is grounded; the anode of the second voltage regulator DZ2 is grounded, and the cathode is connected to the collector of the first transistor Q1.

5. An active noise reducing automatic telephone as claimed in claim 3 wherein: the dual-tone dialing output control circuit comprises a fifth triode Q5, a tenth resistor R10, an eleventh resistor R11, a sixth capacitor C6, a seventh capacitor C7 and an eighth capacitor C8; the fifth triode Q5 is an NPN type triode; a collector of the fifth triode Q5 is connected with a collector of the first triode Q1, a base of the fifth triode Q5 is connected with a DTMF pin of the control chip through an eleventh resistor R11, and an emitter of the fifth triode Q5 is grounded through a tenth resistor R10; the collector of the fifth triode Q5 is also grounded through a sixth capacitor C6; the base of the fifth transistor Q5 is connected to the DTMF pin through a seventh capacitor C7 and also to ground through an eighth capacitor C8.

6. The active noise reduction automatic telephone of claim 5, wherein: the voice amplification and side-tone cancellation circuit comprises a sixth triode Q6, a seventh triode Q7, a second diode D2, a third diode D3, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12 and a thirteenth capacitor C13; the sixth triode Q6 is an NPN type triode, and the seventh triode Q7 is a PNP type triode; a collector of the fifth triode Q5 is connected with an emitter of the seventh triode Q7, a base of the seventh triode Q7 is connected with a collector of the fifth triode Q5 through a twelfth resistor R12, the collector is connected with a first end of a twelfth capacitor C12 through a thirteenth resistor R23, and a second end of the twelfth capacitor C12 is grounded; a collector of the sixth triode Q6 is connected with a base of the fifth triode Q5, the base is connected with a collector of the fifth triode Q5 through a fourteenth resistor R14 and a thirteenth resistor R13, and an emitter is connected with a first end of a twelfth capacitor C12 through a twelfth resistor R22; a first end of the ninth capacitor C9 is connected to a node between the fourteenth resistor R14 and the thirteenth resistor R13, and a second end is grounded; a first end of the tenth capacitor C10 is connected with the base of the sixth triode Q6, and a second end is grounded; the base electrode of the sixth triode Q6 is also connected with the first end of a twelfth capacitor C12 through a twenty-first resistor R21, and the thirteenth capacitor C13 is connected in parallel with two ends of the twenty-first resistor R21; the twentieth resistor R20 is connected with the emitter of the sixth triode Q6 and the collector of the seventh triode Q7; the anode of the second diode D2 is connected to the collector of the seventh transistor Q7 through a nineteenth resistor R19, and the cathode is connected to the emitter of the sixth transistor Q6; an emitter of the seventh triode Q7 is connected with a collector of the seventh triode Q7 through a fifteenth resistor R15, a sixteenth resistor R16 and an eighteenth resistor R18; an eleventh capacitor C11 is connected in parallel with two ends of the fifteenth resistor R15; a first end of the seventeenth resistor R17 is connected to a node between the sixteenth resistor R16 and the eighteenth resistor R18, a second end is connected to an anode of the third diode D3, and a cathode of the third diode D3 is connected to a first end of the twelfth capacitor C12.

7. The active noise reduction automatic telephone of claim 6, wherein: the off-hook dialing noise interference prevention circuit comprises a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a third voltage regulator tube DZ3, a fourteenth capacitor C14, a fifteenth capacitor C15, a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18, a twenty-fourth resistor R24 and a twenty-fifth resistor R25; a node between the sixteenth resistor R16 and the eighteenth resistor R18 is connected with a first end of a fourteenth capacitor C14, a second end of the fourteenth capacitor C14 is connected with an anode of a fourth diode D4 through a fifteenth capacitor C15 and a twenty-fourth resistor R24, and a cathode of the fourth diode D4 is connected with a MUTE pin of the control chip; the second terminal of the fourteenth capacitor C14 is further connected to ground through the sixteenth capacitor C16; the seventeenth capacitor C17 is connected between the first end of the fourteenth capacitor C14 and the cathode of the third diode D3; the anode of the third voltage regulator tube DZ3 is grounded, and the cathode is connected with the cathode of a third diode D3; an anode of the fifth diode D5 is connected to a cathode of the third diode D3, and a cathode thereof is connected to an anode of the sixth diode D6; the cathode of the sixth diode D6 is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the anode of the eighth diode D8; the cathode of the eighth diode D8 is grounded; the cathode of the third diode D3 is also connected to the MUTE pin of the control chip through a twenty-fifth resistor R25; the eighteenth capacitor C18 has a first terminal connected to ground and a second terminal connected to the microphone voice output circuit.

8. The active noise reduction automatic telephone of claim 7, wherein: the first end of the DSP noise reduction module is connected with the base electrode of a sixth triode Q6; the voice signal transmission circuit comprises an eighth triode Q8, a ninth diode D9, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a twenty-ninth resistor R29, a nineteenth capacitor C19, a twentieth capacitor C20, a twenty-first capacitor C21 and a twenty-second capacitor C22; the eighth triode Q8 is an NPN type triode; the anode of the ninth diode D9 is connected to the MUTE pin of the control chip and is also grounded through a twelfth capacitor C22; the cathode of the ninth diode D9 is connected to the collector of the eighth triode Q8 through a twenty-sixth resistor R26, and is further connected to the second end of the DSP noise reduction module through a twenty-seventh resistor R27 and a nineteenth capacitor C19; the base electrode of the eighth triode Q8 is connected to the node between the twenty-seventh resistor R27 and the twenty-sixth resistor R26 through the twenty-eighth resistor R28, and is also grounded through the twenty-first capacitor C21; the emitter of the eighth triode Q8 is grounded; the base of the eighth transistor Q8 is further connected to the first terminal of the twentieth capacitor C20, and the second terminal of the twentieth capacitor C20 is grounded through the twenty-ninth resistor R29.

9. The active noise reduction automatic telephone of claim 8, wherein: the on-HOOK switching circuit comprises a reed pipe plate HOOK, a first field effect tube Q14, a second field effect tube Q15, a forty-first resistor R41 and a forty-second resistor R42; the reed pipe plate HOOK is provided with a first reed pipe and a second reed pipe, wherein the first reed pipe is provided with a first normally open end HOOK1 and a first normally closed end HOOK2, and the second reed pipe is provided with a second normally open end HFMI and a second normally closed end HSMI; the first end of the first reed switch is connected with a first direct current power supply VDD, the second end of the first reed switch can be selectively connected with a first normally-open end HOOK1 and a first normally-closed end HOOK2, and the first normally-open end HOOK1 is grounded through a fourth twelve resistor R42 and is simultaneously connected with the grid electrode of a first field effect transistor Q14; the drain electrode of the first field effect transistor Q14 is connected with the HKS pin of the control chip, and the source electrode is grounded; the first normally-off terminal HOOK2 is grounded through a fourth eleventh resistor R41 and is connected with the gate of the second fet Q15; the drain and source of the second fet Q15 are both grounded.

10. The active noise reduction automatic telephone of claim 9, wherein: the voice input switching circuit comprises a switch SW, a handle microphone MIC and a head microphone HSMT; the first normally closed end HOOK2 is connected with a microphone MIC, and the second normally closed end HSMI is connected with a headset microphone HSMT; the switch SW is disposed between the first reed switch and the second reed switch, a first end of the switch SW is connected to a second end of the twentieth capacitor C20, and a second end of the switch SW is selectively connected to the first normally-closed end HOOK2 or the second normally-closed end HSMI; the first normally closed end HOOK2 is connected with the first end of the microphone MIC, and the second end of the microphone MIC is grounded; the second normally-closed terminal HSMI is connected to the first terminal of the headset microphone HSMT, and the second terminal of the headset microphone HSMT is grounded.

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