阅读说明：本技术 一种红外光通信电路 (Infrared light communication circuit ) 是由 何流 蔡善忠 许国轩 周莉 陈华 于 2020-07-08 设计创作，主要内容包括：本发明提供了一种红外光通信电路,包括滤波放大单元、信号编码单元、红外光发生单元、红外光接收单元、信号解码单元和功率放大单元和若干中继单元；滤波放大单元拾取音频模拟信号,对特定频带范围的音频信号进行放大后输出；信号编码单元对输入的音频模拟信号进行编码后输入红外光发生单元中；红外光发生单元将编码后的音频信号转换为脉冲信号后发出光红外光信号；红外光接收单元将接收到的红外光转换为电压信号并输入信号解码单元中解码后向功率放大单元输出模拟信号；功率放大单元将模拟信号进行功率放大后推动扬声器发出语音信号。(The invention provides an infrared light communication circuit, which comprises a filtering amplification unit, a signal coding unit, an infrared light generation unit, an infrared light receiving unit, a signal decoding unit, a power amplification unit and a plurality of relay units, wherein the filtering amplification unit is used for filtering infrared light; the filtering amplification unit picks up the audio analog signal, amplifies the audio signal in a specific frequency band range and outputs the amplified audio signal; the signal coding unit codes the input audio analog signal and inputs the coded signal into the infrared light generating unit; the infrared light generating unit converts the coded audio signal into a pulse signal and then sends out an optical infrared light signal; the infrared light receiving unit converts the received infrared light into a voltage signal, inputs the voltage signal into the signal decoding unit, decodes the voltage signal and outputs an analog signal to the power amplifying unit; the power amplification unit is used for carrying out power amplification on the analog signal and then pushing the loudspeaker to send out a voice signal.)

1. An infrared optical communication circuit, characterized by: the device comprises a filtering amplification unit (1), a signal coding unit (2), an infrared light generation unit (3), an infrared light receiving unit (4), a signal decoding unit (5), a power amplification unit (6) and a plurality of relay units (7); the output end of the filtering amplification unit (1) is electrically connected with the input end of the signal coding unit (2), the output end of the signal coding unit (2) is electrically connected with the input end of the infrared light generation unit (3), the infrared light receiving unit (4) receives infrared light signals, the output end of the infrared light receiving unit (4) is electrically connected with the input end of the signal decoding unit (5), and the output end of the signal decoding unit (5) is electrically connected with the input end of the power amplification unit (6); the output end of the power amplification unit (6) is electrically connected with an external loudspeaker;

the filtering amplification unit (1) picks up the audio analog signal, amplifies the audio signal in a specific frequency band range and outputs the amplified audio signal;

the signal coding unit (2) codes the input audio analog signal and inputs the coded signal into the infrared light generating unit (3);

the infrared light generating unit (3) converts the coded audio signal into a pulse signal and then sends out an optical infrared light signal;

the relay units (7) are distributed between the infrared light generating unit (3) and the infrared light receiving unit (4) at equal intervals, and transmit infrared light emitted by the infrared light generating unit (3) to the input end of the infrared light receiving unit (4);

the infrared light receiving unit (4) converts the received infrared light into a voltage signal, inputs the voltage signal into the signal decoding unit (5) for decoding, and outputs an analog signal to the power amplifying unit (6);

the power amplification unit (6) performs power amplification on the analog signal and pushes the loudspeaker to send out a voice signal.

2. An infrared optical communication circuit as defined in claim 1, wherein: the signal coding unit (2) comprises a coding chip U1, a capacitor C3 and a triode Q1, an audio analog signal is changed into a voltage signal through a microphone and flows through the capacitor C3, the voltage signal is filtered by the capacitor C3 and then is input into an analog signal input end of a coding chip U1, a digital signal output end of the coding chip U1 outputs a pulse signal through an output pulse signal, and the pulse signal is amplified by the triode Q1 and then is output to an input end of the infrared light generating unit (3); the filtering and amplifying unit (1) filters and converts the input analog signal into a source baseband signal, and the source baseband signal is subjected to analog-to-digital conversion by a coding chip U1 to output a pulse signal.

3. An infrared optical communication circuit as defined in claim 2, wherein: the infrared light generating unit (3) comprises a first PMW generator, a first NAND gate, a second NAND gate, a third NAND gate, a triode Q2, a triode Q3 and a light emitting diode D4, wherein the first input end of the first NAND gate is electrically connected with the output end of the triode Q1, the second input end of the first NAND gate is electrically connected with the output end of the third NAND gate, and two input ends of the third NAND gate are electrically connected with the output end of the first PMW generator; the output end of the first NAND gate is connected with the two input ends of the second NAND gate in parallel, the output end of the second NAND gate is electrically connected with the base of a triode Q2, the emitter of a triode Q2 is electrically connected with the base of a triode Q3, the emitter of a triode Q3 is grounded, the collector of a triode Q3 is respectively connected with the collector of a triode Q2 and the cathode of a light-emitting diode D4 in parallel, and the anode of the light-emitting diode D4 and the collector of the triode Q2 are both electrically connected with a VCC power supply; the PMW signal sent by the first PMW generator is combined with the pulse signal output by the coding chip U1, and the pulse signal is amplified by the cascade connection of the triode Q2 and the Q3 to drive the light-emitting diode D4 to emit infrared light.

4. An infrared optical communication circuit according to claim 3, wherein: the infrared light receiving unit (4) comprises a photosensitive diode D5 and a triode Q4, the positive electrode of the photosensitive diode is electrically connected with the base electrode of the triode Q4, the emitting electrode of the triode Q4 is grounded, and the collecting electrode of the triode Q4 is electrically connected with the input end of the signal decoding unit (5); the anode of the photodiode D5 and the collector of the transistor Q4 are also electrically connected to a +12V power supply.

5. An infrared optical communication circuit according to claim 3, wherein: the signal decoding unit (5) comprises a second PMW generator and a decoding chip U4, wherein PMW emitted by the second PMW generator is input into a clock pin of the decoding chip U4, and the clock frequency of the input decoding chip U4 is the same as that of the encoding chip U1; the output end of the infrared light receiving unit (4) is electrically connected with the digital signal input end of the decoding chip U4, and the analog signal output end of the decoding chip U4 is electrically connected with the input end of the power amplifying unit (6) after voltage regulation; the decoding chip U4 carries out digital-to-analog conversion on the pulse signal received by the infrared light receiving unit (4), and the signal source baseband signal is obtained by decoding.

6. An infrared optical communication circuit as defined in claim 5, wherein: the power amplification unit (6) comprises an operational amplifier U6, an analog signal output end of a decoding chip U4 is electrically connected with a non-inverting input end of an operational amplifier U6, and an inverting input end of the operational amplifier U6 is grounded through a capacitor C13; the output end of the operational amplifier U6 is connected in parallel with a filter circuit formed by serially connecting a capacitor C15 and a resistor R43; the output end of the operational amplifier U6 amplifies the power of the signal source baseband signal and pushes a loudspeaker to send out a voice signal.

7. An infrared optical communication circuit as defined in claim 6, wherein: the coding chip U1 and the decoding chip U4 are MC34115P or STM32 single-chip microcomputer.

8. An infrared optical communication circuit as defined in claim 2, wherein: the filtering amplification unit (1) comprises an operational amplifier U6 and an operational amplifier U7, wherein the non-inverting input end of the operational amplifier U6 is respectively connected in parallel with one end of a resistor R50 and one end of a capacitor C19, the other end of the resistor R50 is electrically connected with the input end of an audio analog signal, and the other end of the capacitor C19 is grounded; a capacitor C20 is connected in parallel between the non-inverting input end and the output end of the operational amplifier U6; the inverting input end of the operational amplifier U6 is respectively connected in parallel with one end of a resistor R52 and one end of a resistor R53, the other end of the resistor R52 is grounded, and the other end of the resistor R53 is connected in parallel with the output end of the operational amplifier U6; the output end of the operational amplifier U6 is electrically connected with the non-inverting input end of the operational amplifier U7 through capacitors C21 and C22 which are connected in series, a resistor R54 is connected between the series end of the capacitor C21 and the capacitor C22 and the output end of the operational amplifier U7 in parallel, the non-inverting input end of the operational amplifier U7 is also connected with a resistor R55 in parallel, the output end of the operational amplifier U7 is connected with two resistors R56 and R57 which are sequentially connected in series in parallel, and the series end of the resistors R56 and R57 is also electrically connected with the inverting input end of the operational amplifier U7; the output end of the operational amplifier U7 is electrically connected with one end of the capacitor C3.

9. An infrared optical communication circuit as defined in claim 1, wherein: the relay unit (7) comprises a photosensitive diode D8, a triode Q5, light-emitting diodes D9 and D10, wherein the anode of the photosensitive diode D8 is electrically connected with the base of a triode Q5, the emitter of the triode Q5 is grounded, and the collector of the triode Q5 is provided with the light-emitting diodes D9 and D10 in series; the relay unit (7) relays the pulse signals sent by the infrared light generating unit (3) step by step and forwards the pulse signals to the input end of the infrared light receiving unit (4).

Technical Field

The invention relates to the technical field of infrared light communication, in particular to an infrared light communication circuit.

Background

Wireless communication technology has become the most common means of communication for humans since the beginning of the 20 th century. Compared with the traditional optical fiber communication technology, the wireless communication technology can transmit large-capacity data such as voice, data and images, and has the advantages of high flexibility, low maintenance cost, no limit of circuit layout space and the like. More typical wireless communication technologies include bluetooth technology, NFC, and infrared light communication technologies. Bluetooth and NFC belong to the short-range wireless transmission technology, although they can realize wireless data transmission, because the cost is too high, the transmission distance is small, the anti-interference ability is weak and the information encryption degree is not enough, the Bluetooth and NFC technology is difficult to be applied to the long-distance wireless communication transmission, and the large-scale research and development and popularization of the Bluetooth and NFC technology are limited.

The infrared light communication technology is used for transmitting audio signals by using infrared light as information transmission signals without resetting frequency bands, so that the infrared light communication can carry out information transmission in a certain space. Because the infrared light communication technology has the advantages of low cost, strong function, high transmission rate, large transmission capacity, high encryption degree and the like, the infrared light communication technology is widely applied to the transmission of short-distance data and information or the file exchange among single devices at present. The distance of transmitting audio signals by infrared light is limited, and the specific application range is limited.

Disclosure of Invention

In view of this, the present invention provides an infrared optical communication circuit with strong anti-interference capability, low power consumption, and expandable remote audio signal transmission capability.

The invention provides an infrared light communication circuit which comprises a filtering amplification unit (1), a signal coding unit (2), an infrared light generation unit (3), an infrared light receiving unit (4), a signal decoding unit (5), a power amplification unit (6) and a plurality of relay units (7); the output end of the filtering amplification unit (1) is electrically connected with the input end of the signal coding unit (2), the output end of the signal coding unit (2) is electrically connected with the input end of the infrared light generation unit (3), the infrared light receiving unit (4) receives infrared light signals, the output end of the infrared light receiving unit (4) is electrically connected with the input end of the signal decoding unit (5), and the output end of the signal decoding unit (5) is electrically connected with the input end of the power amplification unit (6); the output end of the power amplification unit (6) is electrically connected with the loudspeaker;

the filtering amplification unit (1) picks up the audio analog signal, amplifies the audio signal in a specific frequency band range and outputs the amplified audio signal;

the signal coding unit (2) codes the input audio analog signal and inputs the coded signal into the infrared light generating unit (3);

the infrared light generating unit (3) converts the coded audio signal into a pulse signal and then sends out an optical infrared light signal;

the infrared light receiving unit (4) converts the received infrared light into a voltage signal, inputs the voltage signal into the signal decoding unit (5) for decoding, and outputs an analog signal to the power amplifying unit (6);

the power amplification unit (6) performs power amplification on the analog signal and pushes the loudspeaker to send out a voice signal.

On the basis of the above technical solution, preferably, the signal encoding unit (2) includes an encoding chip U1, a capacitor C3 and a triode Q1, the audio analog signal is changed into a voltage signal by a microphone, the voltage signal flows through the capacitor C3, the voltage signal is filtered by the capacitor C3 and then input to the analog signal input end of the encoding chip U1, the digital signal output end of the encoding chip U1 outputs a pulse signal after passing through the output of the pulse signal, and the pulse signal is amplified by the triode Q1 and then output to the input end of the infrared light generating unit (3); the filtering and amplifying unit (1) filters and converts the input analog signal into a source baseband signal, and the source baseband signal is subjected to analog-to-digital conversion by a coding chip U1 to output a pulse signal.

Preferably, the infrared light generating unit (3) includes a first PMW generator, a first nand gate, a second nand gate, a third nand gate, a triode Q2, a triode Q3 and a light emitting diode D4, a first input end of the first nand gate is electrically connected to an output end of the triode Q1, a second input end of the first nand gate is electrically connected to an output end of the third nand gate, and two input ends of the third nand gate are electrically connected to an output end of the first PMW generator; the output end of the first NAND gate is connected with the two input ends of the second NAND gate in parallel, the output end of the second NAND gate is electrically connected with the base of a triode Q2, the emitter of a triode Q2 is electrically connected with the base of a triode Q3, the emitter of a triode Q3 is grounded, the collector of a triode Q3 is respectively connected with the collector of a triode Q2 and the cathode of a light-emitting diode D4 in parallel, and the anode of the light-emitting diode D4 and the collector of the triode Q2 are both electrically connected with a VCC power supply; the PMW signal sent by the first PMW generator is combined with the pulse signal output by the coding chip U1, and the pulse signal is amplified by the cascade connection of the triode Q2 and the Q3 to drive the light-emitting diode D4 to emit infrared light.

Still preferably, the infrared light receiving unit (4) comprises a photodiode D5 and a transistor Q4, wherein the anode of the photodiode is electrically connected to the base of the transistor Q4, the emitter of the transistor Q4 is grounded, and the collector of the transistor Q4 is electrically connected to the input terminal of the signal decoding unit (5); the anode of the photodiode D5 and the collector of the transistor Q4 are also electrically connected to a +12V power supply.

Still further preferably, the signal decoding unit (5) comprises a second PMW generator and a decoding chip U4, the PMW generated by the second PMW generator is input to a clock pin of the decoding chip U4, and the clock frequency of the input decoding chip U4 is the same as the clock frequency of the encoding chip U1; the output end of the infrared light receiving unit (4) is electrically connected with the digital signal input end of the decoding chip U4, and the analog signal output end of the decoding chip U4 is electrically connected with the input end of the power amplifying unit (6) after voltage regulation; the decoding chip U4 carries out digital-to-analog conversion on the pulse signal received by the infrared light receiving unit (4), and the signal source baseband signal is obtained by decoding.

Still preferably, the power amplification unit (6) includes an operational amplifier U6, an analog signal output terminal of the decoding chip U4 is electrically connected to a non-inverting input terminal of the operational amplifier U6, and an inverting input terminal of the operational amplifier U6 is grounded via a capacitor C13; the output end of the operational amplifier U6 is connected in parallel with a filter circuit formed by serially connecting a capacitor C15 and a resistor R43; the output end of the operational amplifier U6 amplifies the power of the signal source baseband signal and pushes a loudspeaker to send out a voice signal.

Still further preferably, the encoding chip U1 and the decoding chip U4 are MC34115P or STM32 single-chip microcomputers.

Further preferably, the filtering and amplifying unit (1) includes an operational amplifier U6 and an operational amplifier U7, a non-inverting input terminal of the operational amplifier U6 is connected in parallel with one end of a resistor R50 and one end of a capacitor C19, the other end of the resistor R50 is electrically connected with an input terminal of the audio analog signal, and the other end of the capacitor C19 is grounded; a capacitor C20 is connected in parallel between the non-inverting input end and the output end of the operational amplifier U6; the inverting input end of the operational amplifier U6 is respectively connected in parallel with one end of a resistor R52 and one end of a resistor R53, the other end of the resistor R52 is grounded, and the other end of the resistor R53 is connected in parallel with the output end of the operational amplifier U6; the output end of the operational amplifier U6 is electrically connected with the non-inverting input end of the operational amplifier U7 through capacitors C21 and C22 which are connected in series, a resistor R54 is connected between the series end of the capacitor C21 and the capacitor C22 and the output end of the operational amplifier U7 in parallel, the non-inverting input end of the operational amplifier U7 is also connected with a resistor R55 in parallel, the output end of the operational amplifier U7 is connected with two resistors R56 and R57 which are sequentially connected in series in parallel, and the series end of the resistors R56 and R57 is also electrically connected with the inverting input end of the operational amplifier U7; the output end of the operational amplifier U7 is electrically connected with one end of the capacitor C3.

On the basis of the above technical solution, preferably, the wireless communication device further comprises a relay unit (7), wherein the relay unit (7) comprises a photodiode D8, a triode Q5, and light emitting diodes D9 and D10, the anode of the photodiode D8 is electrically connected with the base of a triode Q5, the emitter of a triode Q5 is grounded, and the collector of the triode Q5 is provided with the light emitting diodes D9 and D10 in series; the relay unit (7) is positioned between the infrared light generating unit (3) and the infrared light receiving unit (4) and relays and forwards the pulse signal sent by the infrared light generating unit (3) to the input end of the infrared light receiving unit (4).

Compared with the prior art, the infrared light communication circuit provided by the invention has the following beneficial effects:

(1) the invention can realize the conversion of analog signals by configuring the signal coding unit and the signal decoding unit, and eliminate the noise interference in relay transmission as much as possible; the infrared light generating unit and the infrared light receiving unit are matched with the plurality of relay units, so that pulse signals sent by the infrared light generating unit can be transmitted in a long distance without damage, and the problem that the existing infrared light communication is limited by distance is solved;

(2) the filtering and amplifying unit carries out band-pass filtering on the input audio analog signal, filters a noise part of the audio analog signal, reserves a main frequency band part of energy of the audio analog signal and amplifies the audio analog signal;

(3) the signal coding unit performs digital-to-analog conversion on the input analog signal and outputs a pulse signal of a specific information source baseband for further conversion by the infrared light generating unit;

(4) the infrared light generating unit compounds the PMW signal sent by the first PMW generator and the pulse signal output by the coding chip U1, and the PMW signal is amplified in a cascade mode through a triode Q2 and a Q3, so that the load capacity is improved, and the infrared light signal with high energy is output;

(5) the signal decoding unit carries out digital-to-analog conversion according to the received pulse signal and restores the pulse signal into an information source baseband signal;

(6) the power amplification unit amplifies the power of the information source baseband signal and then pushes the loudspeaker to send out a voice signal.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a system block diagram of an IR communication circuit according to the present invention;

FIG. 2 is a wiring diagram of a signal encoding unit of an IR communication circuit according to the present invention;

FIG. 3 is a wiring diagram of an IR light generating unit of an IR communication circuit according to the present invention;

FIG. 4 is a wiring diagram of an IR receiving unit and a signal decoding unit of an IR communication circuit according to the present invention;

FIG. 5 is a wiring diagram of a power amplifying unit of an IR communication circuit according to the present invention;

FIG. 6 is a wiring diagram of a relay unit of an IR communication circuit according to the present invention;

fig. 7 is a wiring diagram of a filtering and amplifying unit of an infrared light communication circuit according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 1, an infrared communication circuit is shown, which includes a filtering amplification unit 1, a signal encoding unit 2, an infrared light generation unit 3, an infrared light receiving unit 4, a signal decoding unit 5, a power amplification unit 6, and a plurality of relay units 7; the output end of the filtering amplification unit 1 is electrically connected with the input end of the signal coding unit 2, the output end of the signal coding unit 2 is electrically connected with the input end of the infrared light generation unit 3, the infrared light receiving unit 4 receives infrared light signals, the output end of the infrared light receiving unit 4 is electrically connected with the input end of the signal decoding unit 5, and the output end of the signal decoding unit 5 is electrically connected with the input end of the power amplification unit 6; the output end of the power amplification unit 6 is electrically connected with the loudspeaker; wherein:

the filtering and amplifying unit 1 is used for picking up an audio analog signal, amplifying the audio signal in a specific frequency band range and then outputting the amplified audio signal;

a signal encoding unit 2 for encoding the input audio analog signal and inputting the encoded audio analog signal into an infrared light generating unit 3;

the infrared light generating unit 3 is used for converting the coded audio signal into a pulse signal and then sending out an optical infrared light signal;

an infrared light receiving unit 4 for converting the received infrared light into a voltage signal, inputting the voltage signal into a signal decoding unit 5 for decoding, and outputting an analog signal to a power amplifying unit 6;

the signal decoding unit 5 converts the received pulse signal into an analog signal;

the power amplification unit 6 performs power amplification on the analog signal and pushes the loudspeaker to send out a voice signal.

As shown in fig. 2, a wiring diagram of a signal encoding unit 2 is shown. The signal coding unit 2 comprises a coding chip U1, a capacitor C3 and a triode Q1, an audio analog signal is changed into a voltage signal through a microphone and flows through the capacitor C3, the voltage signal is filtered by the capacitor C3 and then is input into an analog signal input end of the coding chip U1, a digital signal output end of the coding chip U1 outputs a pulse signal, and the pulse signal is amplified by the triode Q1 and then is output to an input end of the infrared light generating unit 3; the filtering and amplifying unit 1 filters the input analog signal and converts the filtered analog signal into a source baseband signal, and the source baseband signal is subjected to analog-to-digital conversion by an encoding chip U1 to output a pulse signal. The encoding chip U1 is shown as MC34115P, which is a modem that performs both modulation and demodulation functions. An analog signal input by the capacitor C3 is input into a pin 1 of the encoding chip U1; pin 2 is a feedback input end, when encoding works, a local analog signal is input into a comparator in an encoding chip U1 from the feedback input end, and when decoding works, the pin is suspended or connected with pin 10; the pin 9 of the coding chip U1 is a digital output terminal, which is also a coding output, compatible with TTL or CMOS, and has a low level, so that a triode Q1 is used for amplifying and outputting, and the output voltage is V1. Pin 10 is a reference voltage output. Pin 14 is the codec clock input, which determines the operating speed of the chip, and may be 8KHz, 16KHz, 32KHz or 64 KHz. The pin 15 is an encoding/decoding selection function, and has an encoding function at a high level and a decoding function at a low level. Pin 1 is also shown connected in parallel with the non-inverting input of an operational amplifier, the output of which serves as the input signal to the incremental control input of pin 4.

As shown in fig. 7, the filtering and amplifying unit 1 includes an operational amplifier U6 and an operational amplifier U7, a non-inverting input terminal of the operational amplifier U6 is connected in parallel with one end of a resistor R50 and one end of a capacitor C19, the other end of the resistor R50 is electrically connected to an input terminal of the audio analog signal, and the other end of the capacitor C19 is grounded; a capacitor C20 is connected in parallel between the non-inverting input end and the output end of the operational amplifier U6; the inverting input end of the operational amplifier U6 is respectively connected in parallel with one end of a resistor R52 and one end of a resistor R53, the other end of the resistor R52 is grounded, and the other end of the resistor R53 is connected in parallel with the output end of the operational amplifier U6; the output end of the operational amplifier U6 is electrically connected with the non-inverting input end of the operational amplifier U7 through capacitors C21 and C22 which are connected in series, a resistor R54 is connected between the series end of the capacitor C21 and the capacitor C22 and the output end of the operational amplifier U7 in parallel, the non-inverting input end of the operational amplifier U7 is also connected with a resistor R55 in parallel, the output end of the operational amplifier U7 is connected with two resistors R56 and R57 which are sequentially connected in series in parallel, and the series end of the resistors R56 and R57 is also electrically connected with the inverting input end of the operational amplifier U7; the output end of the operational amplifier U7 is electrically connected with one end of the capacitor C3. The filtering amplification unit 1 realizes band-pass filtering through two stages of operational amplifiers and screens sound frequency between 340Hz and 3 KHz.

As shown in fig. 3, the infrared light generating unit 3 includes a first PMW generator, a first nand gate, a second nand gate, a third nand gate, a triode Q2, a triode Q3 and a light emitting diode D4, a first input end of the first nand gate is electrically connected to an output end of the triode Q1, a second input end of the first nand gate is electrically connected to an output end of the third nand gate, and two input ends of the third nand gate are both electrically connected to an output end of the first PMW generator; the output end of the first NAND gate is connected with the two input ends of the second NAND gate in parallel, the output end of the second NAND gate is electrically connected with the base of a triode Q2, the emitter of a triode Q2 is electrically connected with the base of a triode Q3, the emitter of a triode Q3 is grounded, the collector of a triode Q3 is respectively connected with the collector of a triode Q2 and the cathode of a light-emitting diode D4 in parallel, and the anode of the light-emitting diode D4 and the collector of the triode Q2 are both electrically connected with a VCC power supply; the PMW signal sent by the first PMW generator is combined with the pulse signal output by the coding chip U1, and the pulse signal is amplified by the cascade connection of the triode Q2 and the Q3 to drive the light-emitting diode D4 to emit infrared light. The first PMW generator can be generated by a common PMW wave generating chip and can also be realized by a PMW output end of an STM32 singlechip. The first nand gate, the second nand gate and the third nand gate can be implemented by using an integrated chip U3 CD 4011B. The conditioned pulse waveform is input into a cascaded triode Q2 and a cascaded triode Q3, a light emitting diode D3 is arranged on a collector of the triode Q2 and can be used as a work indication signal, and the light emitting diode D4 emits infrared light.

As shown in fig. 4, the infrared light receiving unit 4 includes a photodiode D5 and a transistor Q4, wherein an anode of the photodiode is electrically connected to a base of the transistor Q4, an emitter of the transistor Q4 is grounded, and a collector of the transistor Q4 is electrically connected to an input terminal of the signal decoding unit 5; the anode of the photodiode D5 and the collector of the transistor Q4 are also electrically connected to a +12V power supply. The photodiode D5 generates a corresponding signal after receiving the infrared light signal, and the signal is amplified by the transistor Q4 and then input to the input terminal of the signal decoding unit 5.

As also shown in fig. 4, the signal decoding unit 5 includes a second PMW generator and a decoding chip U4, the PMW generated by the second PMW generator is input to a clock pin of the decoding chip U4, and the clock frequency input to the decoding chip U4 is the same as the clock frequency of the encoding chip U1; the output end of the infrared light receiving unit 4 is electrically connected with the digital signal input end of the decoding chip U4, and the analog signal output end of the decoding chip U4 is electrically connected with the input end of the power amplifying unit 6 after voltage regulation; the decoding chip U4 performs digital-to-analog conversion on the pulse signal received by the infrared light receiving unit 4, and decodes the pulse signal to obtain an information source baseband signal. The decoding chip U4 may also adopt MC34115P, and operate in the decoding state. The signal is input by pin 13 and the decoded signal is output by pin 7. The second PMW generator correspondingly generates a PMW waveform as a clock signal for the decoder chip U4.

As shown in fig. 5, the power amplifying unit 6 includes an operational amplifier U6, an analog signal output terminal of the decoding chip U4 is electrically connected to a non-inverting input terminal of the operational amplifier U6, and an inverting input terminal of the operational amplifier U6 is grounded via a capacitor C13; the output end of the operational amplifier U6 is connected in parallel with a filter circuit formed by serially connecting a capacitor C15 and a resistor R43; the output end of the operational amplifier U6 amplifies the power of the signal source baseband signal and pushes a loudspeaker to send out a voice signal.

As shown in fig. 6, the relay unit 7 includes a photodiode D8, a transistor Q5, and light emitting diodes D9 and D10, wherein an anode of the photodiode D8 is electrically connected to a base of the transistor Q5, an emitter of the transistor Q5 is grounded, and a collector of the transistor Q5 is connected in series with the light emitting diodes D9 and D10; the relay unit 7 is located between the infrared light generation unit 3 and the infrared light receiving unit 4, and relays and forwards the pulse signal sent by the infrared light generation unit 3 to the input end of the infrared light receiving unit 4. The relay units 7 are arranged at equal intervals, so that the signals are prevented from being attenuated due to the extension of the distance.

Of course, the encoding chip U1 and the decoding chip U4 of the invention can also adopt an STM32 singlechip, the singlechip has ADC function and PMW output function, the integration level is higher, and the circuit structure can be simplified.

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 invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.