CN114333196A - A kind of infrared grating alarm signal amplifying circuit and amplifying method - Google Patents

Abstract

The invention provides a signal amplifying circuit and amplifying method for an infrared grating alarm, comprising an infrared encoding transmitting circuit for transmitting infrared light signals, an infrared decoding receiving circuit for decoding the infrared light signals, and an infrared decoding receiving circuit connected with the infrared decoding receiving circuit for receiving infrared light an optical signal amplifying circuit for signals; the optical signal amplifying circuit includes a first-stage operational amplifier circuit that amplifies the received infrared light signal in the first stage, and a first-stage amplifier that performs frequency selection on the infrared light signal after the first-stage amplification. A filter circuit and a second-stage operational amplifier circuit for second-stage amplifying the infrared light signal after the filling wave; the filter circuit includes a high-pass filter and a low-pass filter arranged in parallel. The invention has the advantages that the amplification and restoration of the attenuated small signal after long-distance transmission can be well realized, the infrared light signal is not distorted after restoration, and can be decoded effectively, thereby ensuring the detection distance of the infrared grating alarm.

Description

A kind of infrared grating alarm signal amplifying circuit and amplifying method

【Technical field】

The invention relates to the technical field of infrared grating alarms, in particular to a signal amplifying circuit and amplifying method of an infrared grating alarm.

【Background technique】

Infrared grating alarm is a kind of active infrared radiation, which uses multiple beams of infrared light to emit infrared light from the transmitter to the receiver in the way of "low frequency emission, time division detection". When any two or more adjacent beams of light exceed 30ms, the receiver will output an alarm signal immediately, and when there is a small animal or a small object blocking one of the beams, the alarm will not output an alarm signal.

Infrared grating alarm is the front-end product of new family anti-theft guarding windows and balconies that replace the "iron castle" and traditional technology to prevent the door and window magnetic control switches, curtain detectors and other products, and various anti-theft alarm controllers. Powerful anti-theft alarm system. According to the working principle of the infrared light grid alarm, it can also be extended to various uses, such as vehicle detection in indoor parking lots. In order to solve the technical problem of false alarms caused by sunlight interference caused by the traditional one-way infrared grating, the new generation of infrared grating alarm adopts the frequency conversion mutual emission technology, which avoids the problem of direct sunlight, flashlights and car lights, and realizes the True zero false positives.

The detection distance of the infrared grating alarm is 5-250 meters. Because the infrared light signal has signal attenuation in the process of long-distance transmission, in order to extend the detection distance of the infrared grating alarm, traditionally, increasing the transmission power and using a small angle are used. However, in the process of practical application, increasing the infrared emission power or using laser and other emission methods will cause damage to the human retina, which is not conducive to human health. In view of the above-mentioned problems, the inventor of this case conducted in-depth research on the problem, and this case came into being.

[Content of the invention]

The technical problem to be solved by the present invention is to provide an infrared grating alarm signal amplifying circuit and an amplifying method, which can effectively amplify and restore the long-distance transmitted infrared light signal on the basis of reducing the damage caused by infrared rays to the human body. So as to ensure the detection distance.

The present invention is realized in this way:

In the first aspect, an infrared grating alarm signal amplifier circuit includes an infrared encoding transmitting circuit for transmitting infrared light signals, an infrared decoding receiving circuit for decoding infrared light signals, and a light receiving circuit for receiving infrared light signals connected to the infrared decoding receiving circuit. Signal amplifying circuit;

The optical signal amplifying circuit includes a first-stage operational amplifier circuit that amplifies the received infrared light signal in the first stage, a filter circuit that performs frequency selection on the first-stage amplified infrared light signal, and a filter circuit that amplifies the infrared light signal in the first stage. A second-stage operational amplifier circuit for the second-stage amplification of the infrared light signal; the filter circuit includes a high-pass filter and a low-pass filter arranged in parallel.

Preferably, the high-pass filter includes at least two stages of high-pass filter circuits, and the low-pass filter includes at least two stages of low-pass filter circuits.

Preferably, the first stage operational amplifier circuit includes an infrared receiving tube DS1, a resistor R11, a capacitor C26, a resistor R57, a resistor R58, a first operational amplifier U3A, a resistor R41, a resistor R46, a resistor R45, a capacitor C10 and a capacitor C14 ;

One end of the resistor R11 and the capacitor C26 is connected to the infrared receiving tube DS1, and the other end of the resistor R11 is grounded; the resistor R57 and the resistor R58 are arranged in parallel, and the other end of the capacitor C26, one end of the resistor R57 and the resistor R58 are connected in parallel. One end is connected to the same-direction input end of the first operational amplifier U3A, the other end of the resistor R58 is connected to the reference voltage, and the other end of the resistor R57 is grounded;

One end of the resistor R45 is connected to the reverse input terminal of the first operational amplifier U3A, and the other end of the resistor R45 is grounded through the capacitor C10; one end of the resistor R46 is connected to the reverse input terminal of the first operational amplifier U3A, One end of the resistor R41 is connected to the output end of the first operational amplifier U3A, and the other ends of the resistor R46 and the resistor R41 are both grounded through the capacitor C14.

Preferably, the first-stage operational amplifier circuit further includes a capacitor C18 and a capacitor C15; the capacitor C18 is arranged between the non-inverting input terminal and the reverse input terminal of the first operational amplifier U3A; the capacitor C15 is arranged between Between the resistor R41 and the resistor R46.

Preferably, the second-stage operational amplifier circuit includes a first operational amplifier U3B, a resistor R29, a resistor R40, a resistor R44, a capacitor C4 and a capacitor C23;

One end of the resistor R44 and the resistor R40 are both connected to the reverse input end of the first operational amplifier U3B, one end of the resistor R29 is connected to the output end of the first operational amplifier U3B, and the other end of the resistor R44 is grounded through the capacitor C23, The other ends of resistor R40 and resistor R29 are connected to ground through capacitor C4.

Preferably, the second-stage operational amplifier circuit further includes a capacitor C17 and a capacitor C12; the capacitor C17 is provided between the inverting input terminal and the non-inverting input terminal of the first operational amplifier U3B, and the capacitor C12 is provided in the resistor R40 and resistor R29.

Preferably, the high-pass filter includes a first-stage high-pass filter circuit composed of a capacitor C5, a resistor R30, and a capacitor C6, and a second-stage high-pass filter circuit composed of a capacitor C9, a resistor R56, and a capacitor C16;

The low-pass filter includes a first-stage low-pass filter circuit composed of resistor R32, capacitor C7, capacitor C8, and resistor R31, and a second-stage low-pass filter circuit composed of resistor R39, capacitor C21, and resistor R54.

Preferably, an LC filter circuit connected to the second-stage operational amplifier circuit is also included.

In a second aspect, a method for amplifying a signal of an infrared grating alarm device, the amplifying method uses the above-mentioned signal amplifying circuit, and the amplifying method includes:

The infrared encoding transmitting circuit transmits the encoded infrared light signal, and the encoded infrared light signal is composed of the transceiver mode code + preamble code + start code + data code;

The optical signal amplifying circuit receives the infrared light signal emitted by the infrared coding transmitting circuit, inputs the infrared light signal into the first-stage operational amplifier circuit for first-stage amplification, and inputs the first-stage amplified infrared light signal into the filter circuit Carry out frequency selection filling wave, input the infrared light signal after frequency selection filling wave into the second-stage operational amplifier circuit for second-stage amplification, and output the second-stage amplified infrared light signal;

The infrared decoding receiving circuit receives the infrared light signal output by the optical signal amplifying circuit, and decodes the received infrared light signal according to the coding protocol.

By adopting the technical scheme of the present invention, at least the following beneficial effects are obtained:

1. The first-stage operational amplifier circuit and the second-stage operational amplifier circuit are used to amplify the received infrared light signal in two stages, and a filter circuit is set between the first-stage operational amplifier circuit and the second-stage operational amplifier circuit. The frequency selection of the infrared light signal after the first-stage amplification process can effectively remove the high and low-frequency interference signals; therefore, through the first-stage operational amplifier circuit, filter circuit and second-stage operational amplifier circuit The mutual cooperation of the remote transmission can effectively amplify and restore the attenuated small signal after long-distance transmission, and the infrared light signal is not distorted after restoration, and can be effectively decoded, thereby ensuring the detection distance of the infrared grating alarm; at the same time; Compared with the existing use of increasing the infrared emission power or using laser and other emission methods to extend the detection distance, it can effectively reduce the damage caused by infrared rays to the human body.

2. By designing a high-pass filter including at least two stages of high-pass filter circuits, and a low-pass filter including at least two stages of low-pass filter circuits, it is possible to effectively fill a variety of interference signals through frequency selection and avoid noise signals. are synchronously amplified and cause signal distortion.

3. There is a transceiver mode setting switch on the microcontroller, so that the receiving mode of the infrared grating alarm can be flexibly set according to actual needs during specific use, so that there is no need to distinguish the transmitting end and the receiving end during installation. After the installation is completed, the transceiver mode can be set through the transceiver mode setting switch, so it is more flexible and convenient to use.

【Description of drawings】

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Figure 1 is the equivalent circuit diagram of the infrared grating alarm when it is working;

Fig. 2 is the principle block diagram of a kind of infrared grating alarm signal amplifier circuit of the present invention;

Fig. 3 is the principle block diagram of the optical signal amplifying circuit in the present invention;

Fig. 4 is the principle block diagram of filter circuit in the present invention;

Fig. 5 is the circuit diagram of the single-chip microcomputer in the present invention;

6 is a circuit diagram of an optical signal amplifying circuit in the present invention;

Fig. 7 is the circuit diagram of infrared coding transmitting circuit in the present invention;

Fig. 8 is the waveform diagram of the carrier wave that infrared coding transmitting circuit of the present invention uses when transmitting;

Fig. 9 is a signal coding protocol diagram in the present invention.

【Detailed ways】

In order to better understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

It should be noted here that the terms "first", "second", etc. are only used for descriptive purposes, and should not be understood as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first", "second", etc., may expressly or implicitly include one or more of that feature.

Referring to FIG. 1 , the infrared grating alarm includes a transmitting end 100 and a receiving end 200 , and in specific use, two infrared grating alarms are usually used together. Taking the application of the infrared grating alarm in the access control system as an example, it is necessary to set an infrared grating alarm on both sides of the access control, and the infrared grating alarms on both sides are set oppositely; when the access control system is turned on, it is located on one side. The infrared grating alarm will transmit multiple beams of infrared light signals to the infrared grating alarm located on the other side through the transmitting end 100, and the infrared grating alarm on the other side will receive the infrared light signal through the receiving end 200; When the object passes through the access control system and blocks any two or more adjacent infrared rays, the receiving end 200 of the infrared grating alarm on the other side will output an alarm signal because it cannot receive the infrared signal normally, thereby realizing the alarm function.

In specific applications, due to different applications, the detection distance requirements of the infrared grating alarm are also different. When the required detection distance is relatively long, because the infrared light signal has signal attenuation during long-distance transmission, there is a receiving end 200. A situation in which the signal cannot be decoded normally and thus cannot meet the detection distance requirement. In order to solve the problem of the detection distance of the infrared grating alarm, the present invention adopts an optical signal amplifying circuit at the receiving end 200, and uses the optical signal amplifying circuit to amplify and separate the noise of the weak infrared light signal after attenuation, so as to realize the infrared light signal. Restore, and then send the restored infrared light signal to decoding, which can effectively ensure the normal decoding of the signal, thereby ensuring the detection distance of the infrared grating alarm.

first embodiment

Please refer to FIG. 2 to FIG. 7 , a signal amplifying circuit of an infrared grating alarm device of the present invention includes an infrared encoding transmitting circuit 1 for transmitting infrared light signals, an infrared decoding receiving circuit 2 for decoding infrared light signals, and an infrared decoding receiving circuit. The 2-phase is connected to the optical signal amplifying circuit 3 for receiving infrared light signals; after the infrared encoding transmitting circuit 1 of the transmitting end 100 emits the infrared light signal, the receiving end 200 first receives the infrared light signal through the optical signal amplifying circuit 3, and then transmits the infrared light signal. The infrared light signal is amplified and de-noised and restored, and then the restored infrared light signal is output to the infrared decoding receiving circuit 2 for decoding.

The optical signal amplifying circuit 3 includes a first-stage operational amplifier circuit 31 that performs a first-stage amplification on the received infrared light signal, a filter circuit 32 that performs frequency selection on the first-stage amplified infrared light signal, and A second-stage operational amplifier circuit 33 for second-stage amplification of the infrared light signal after the stuffing wave; the filter circuit 32 includes a high-pass filter 321 and a low-pass filter 322 arranged in parallel. During operation, after receiving the infrared light signal, the optical signal amplifying circuit 3 will first send the infrared light signal to the first-stage operational amplifier circuit 31 for first-stage amplification processing; The signal is sent to the filter circuit 32 for filtering and denoising processing. Because the filter circuit 32 includes a high-pass filter 321 and a low-pass filter 322, both high-frequency interference signals and low-frequency interference signals can be attenuated; The infrared light signal is sent to the second-stage operational amplifier circuit 33 for second-stage amplification processing.

Because when amplifying the received infrared light signal, if only one-stage amplification processing is performed on the infrared light signal, the signal is in a distorted state, which is not conducive to the decoding of the infrared decoding receiving circuit 2; Not only will it increase the cost, but there is a possibility of falling into self-excitation (especially when it exceeds level 3). In the present invention, the first-stage operational amplifier circuit 31 and the second-stage operational amplifier circuit 33 are used to amplify the received infrared light signal in two stages. Setting the filter circuit 32 to perform frequency selection on the infrared light signal after the first-stage amplification process can effectively remove high and low-frequency interference signals; therefore, through the first-stage operational amplifier circuit 31 and the filter circuit 32 The mutual cooperation with the second-stage op amp circuit 33 can well realize the amplification and restoration of the small signal after long-distance transmission attenuation, and the infrared light signal is not distorted after restoration, and can be decoded effectively, so as to ensure the infrared light signal. The detection distance of the grating alarm; at the same time, compared with the existing use of increasing the infrared emission power or using lasers and other emission methods to extend the detection distance, it can effectively reduce the damage caused by infrared rays to the human body.

In the present invention, the infrared decoding and receiving circuit 2 is realized by the single-chip microcomputer U1; at the same time, the single-chip microcomputer U1 has a transceiver mode setting switch S1, and in specific use, the transceiver mode of the infrared grating alarm can be set through the transceiver mode setting switch S1 For example, when the transceiver mode setting switch S1 is set to the receiving mode, the infrared grating alarm is used as the receiving end 200; and when the transceiver mode setting switch S1 is set to the transmitting mode, the infrared grating alarm device is used as the transmitting end 100. .

In the present invention, the transceiver mode setting switch S1 is set on the single-chip microcomputer U1, so that the receiving mode of the infrared grating alarm can be flexibly set according to actual needs during specific use, so that the transmitter 100 and the receiver 200 need not be installed during installation. To distinguish, you only need to set the transceiver mode through the transceiver mode setting switch S1 after the installation is completed, so it is more flexible and convenient to use. Preferably, the model of the single-chip microcomputer U1 is STM8S003.

In some embodiments of the present invention, the high-pass filter 321 includes at least two stages of high-pass filter circuits, and the low-pass filter 322 includes at least two stages of low-pass filter circuits, wherein each stage of high-pass filter circuits The center frequency of the stuffing wave is different, and the center frequency of the stuffing wave of each stage of the low-pass filter circuit is also different. Because in the specific implementation, there may be various high-frequency interference signals and various low-frequency interference signals in the infrared light signal after the first-stage amplification process. Therefore, in the present invention, by designing the high-pass filter 321 to include at least two-stage high-pass filter circuits, and the low-pass filter 322 to include at least two-stage low-pass filter circuits, the A variety of interference signals are effectively filled to prevent the noise signal from being amplified synchronously and causing signal distortion.

In the specific implementation, the center frequency of the stuffed wave can be calculated according to fo=1/(2πRC), where R is the resistance value of the equivalent resistance, and C is the capacitance value of the equivalent capacitor; When the high-frequency interference signal is 90kHz, a high-pass filter circuit with the center frequency of the stuffing wave at 85kHz can be designed to realize the stuffing wave for the high-frequency interference signal.

Preferably, in order to reduce the design complexity of the entire signal amplifying circuit and at the same time ensure a better filling wave effect, in the present invention, the high-pass filter 321 is designed to include a first stage composed of a capacitor C5, a resistor R30, and a capacitor C6 The high-pass filter circuit 3211 and the second-stage high-pass filter circuit 3212 composed of capacitor C9, resistor R56 and capacitor C16, wherein the center frequency of the filling wave of the first-stage high-pass filter circuit 3211 is calculated by capacitor C5, resistor R30 and capacitor C6, The center frequency of the stuffing wave of the second-stage high-pass filter circuit 3212 is calculated by capacitor C9, resistor R56 and capacitor C16;

The low-pass filter 322 includes a first-stage low-pass filter circuit 3221 composed of a resistor R32, a capacitor C7, a capacitor C8, and a resistor R31, and a second-stage low-pass filter circuit 3222 composed of a resistor R39, a capacitor C21, and a resistor R54. , where the center frequency of the stuffing wave of the first-stage low-pass filter circuit 3221 is calculated by resistor R32, capacitor C7, capacitor C8 and resistor R31, and the second-stage low-pass filter circuit 3222 is calculated by resistor R39, capacitor C21 and resistor R54. .

In some embodiments of the present invention, the first-stage operational amplifier circuit 31 includes an infrared receiving tube DS1, a resistor R11, a capacitor C26, a resistor R57, a resistor R58, a first operational amplifier U3A, a resistor R41, a resistor R46, a resistor R45, capacitor C10 and capacitor C14;

One end of the resistor R11 and the capacitor C26 is connected to the infrared receiving tube DS1, and the other end of the resistor R11 is grounded; the resistor R57 and the resistor R58 are arranged in parallel, and the other end of the capacitor C26, one end of the resistor R57 and the resistor R58 are connected in parallel. One end is connected to the same-direction input end of the first operational amplifier U3A, the other end of the resistor R58 is connected to the reference voltage VCC, and the other end of the resistor R57 is grounded;

One end of the resistor R45 is connected to the reverse input terminal of the first operational amplifier U3A, and the other end of the resistor R45 is grounded through the capacitor C10; one end of the resistor R46 is connected to the reverse input terminal of the first operational amplifier U3A, One end of the resistor R41 is connected to the output end of the first operational amplifier U3A, and the other ends of the resistor R46 and the resistor R41 are grounded through a capacitor C14, which is a bypass capacitor for filtering out unwanted high-frequency interference.

When the first-stage operational amplifier circuit 31 is in operation, after the infrared receiving tube DS1 receives the infrared light signal, it inputs the infrared light signal into the resistor R11 and generates the V_R11 voltage. The V_R11 voltage is coupled through the capacitor C26 and superimposed on the resistor R58 / resistor R57. After the reference voltage is reduced, it is input to the non-inverting input terminal of the first operational amplifier U3A for amplification; the resistor R41, the resistor R46, the resistor R45, the capacitor C10 and the capacitor C14 form the AC input to the reverse input terminal of the first operational amplifier U3A. Signal amplification circuit, the multiple of signal amplification is about Rf1=(1+(R41+R46)/R45)*V_R57.

In some embodiments of the present invention, the first-stage operational amplifier circuit 31 further includes a capacitor C18 and a capacitor C15; the capacitor C18 is disposed between the non-inverting input terminal and the inverting input terminal of the first operational amplifier U3A ; The capacitor C15 is set between the resistor R41 and the resistor R46; wherein, the capacitor C18 and the capacitor C15 are high-frequency suppression capacitors for suppressing differential mode noise interference.

In some embodiments of the present invention, the second-stage operational amplifier circuit 33 includes a first operational amplifier U3B, a resistor R29, a resistor R40, a resistor R44, a capacitor C4, and a capacitor C23;

One end of the resistor R44 and the resistor R40 are both connected to the reverse input end of the first operational amplifier U3B, one end of the resistor R29 is connected to the output end of the first operational amplifier U3B, and the other end of the resistor R44 is grounded through the capacitor C23, The other ends of resistor R40 and resistor R29 are connected to ground through capacitor C4.

When the second-stage operational amplifier circuit 33 is in operation, the output of the filter circuit 32 is directly input to the non-inverting input terminal of the first operational amplifier U3B for amplification; resistor R29, resistor R40, resistor R44, capacitor C4 and capacitor C23 constitutes an AC signal amplifying circuit that is input to the reverse input end of the first operational amplifier U3B. The multiple of signal amplification is about Rf2=(1+(R29+R40)/R44)*Vo1, and Vo1 is the voltage output by the filter circuit 32 .

In some embodiments of the present invention, the second-stage operational amplifier circuit further includes a capacitor C17 and a capacitor C12; the capacitor C17 is arranged between the inverting input terminal and the non-inverting input terminal of the first operational amplifier U3B, The capacitor C12 is set between the resistor R40 and the resistor R29; wherein, the capacitor C17 and the capacitor C12 are both high-frequency suppression capacitors for suppressing differential mode noise interference.

In some embodiments of the present invention, an LC filter circuit 4 connected to the second-stage operational amplifier circuit 33 is further included, the LC filter circuit 4 is used for smoothing the output signal, and the output of the LC filter circuit 4 is the same as that of the single-chip microcomputer U1 connected, so as to transmit the amplified and restored infrared light signal to the single-chip microcomputer U1 for decoding. The LC filter circuit 4 includes a resistor R59, a resistor R47, a capacitor C19 and a capacitor C1-9, wherein the resistor R59 and the capacitor C19 form the first-stage LC filter, and the resistor R47 and the capacitor C1-9 form the second-stage LC filter. Two-stage LC filtering can achieve better smoothing effect and ensure the quality of the output signal.

In some embodiments of the present invention, the infrared code transmitting circuit 1 includes a resistor R1-1, a resistor R1-2, a resistor R13, an infrared emission tube DS and a triode Q4, wherein the b-pole of the triode Q4 passes through the resistor R1-2 It is connected to the microcontroller U1, the c pole of the transistor Q4 is connected to the battery BAT through the infrared emission tube DS, the e pole of the transistor Q4 and one end of the resistor R13 are grounded, and the other end of the resistor R13 is connected to the b pole of the transistor Q4; , When the infrared grating alarm is used as the transmitting end 100, the single-chip microcomputer U1 controls the transistor Q4 to conduct, so that the infrared transmitting tube DS emits infrared light signals.

Second Embodiment

Please refer to FIG. 1 to FIG. 9 , a method for amplifying a signal of an infrared grating alarm according to the present invention. The amplifying method requires a signal amplifying circuit. Please refer to the detailed introduction of the first embodiment for the specific structure of the signal amplifying circuit. , and will not be repeated here.

The amplifying method includes:

Step S1, the infrared encoding transmitting circuit 1 transmits an encoded infrared light signal, and the encoded infrared light signal is composed of a transceiver mode code+preamble code+start code+data code, and please refer to the following Table 1 for the specific encoding protocol;

Table 1 Parameter table of signal coding protocol

In step S1, the infrared code transmitting circuit 1 transmits data in a modulated manner. It performs an AND operation on the data and a carrier of a certain frequency before transmitting. The modulated carrier frequency is between 30kHz and 60kHz, and the A square wave with a duty cycle of 1/3 is used, as shown in Figure 8, which is determined by the 455kHz crystal oscillator used by the single-chip microcomputer U1 of the transmitter 100, that is, the present invention directly utilizes the internal crystal oscillator of the single-chip microcomputer U1, and does not require Then set the external crystal oscillator; at the transmitting end 100, the crystal oscillator needs to be divided into integer frequency, and the frequency dividing coefficient is generally 12, so the transmitting frequency is 455kHz÷12≈37.9kHz≈38kHz. The transmission efficiency is reduced, and the transmission power consumption is reduced; of course, in the specific implementation, the frequency division coefficient can be adjusted according to actual needs.

Step S2, the optical signal amplifying circuit 3 receives the infrared light signal emitted by the infrared coding transmitting circuit 1, inputs the infrared light signal into the first-stage operational amplifier circuit 31 for first-stage amplification, and amplifies the infrared light signal after the first-stage amplification Input into the filter circuit 32 for frequency-selective filling wave, thereby filtering out noise interference, input the infrared light signal after frequency-selecting filling-wave into the second-stage operational amplifier circuit 33 for second-stage amplification, and amplify the second-stage After the infrared light signal output;

In the step S2, the output of the second-stage amplified infrared light signal specifically includes: firstly outputting the second-stage amplified infrared light signal to the LC filter circuit 4 for smoothing filtering, and then smoothing and filtering The resulting infrared light signal is output to the infrared decoding receiving circuit 2 .

Step S3, the infrared decoding receiving circuit 2 receives the infrared light signal output by the optical signal amplifying circuit 3, and decodes the received infrared light signal according to the coding protocol;

The specific decoding process of the infrared decoding receiving circuit 2 (that is, the single-chip microcomputer U1) is as follows: the single-chip microcomputer U1 is set to the receiving mode and the system is initialized, the timer is started for timing, the preamble code is detected, the start code is detected, and then the data code is read; at the same time; After receiving the transmitting code, the single-chip microcomputer U1 will feed back a confirmation code to the transmitting end 100 to verify the accuracy of the data.

Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments we describe are only illustrative, rather than used to limit the scope of the present invention. Equivalent modifications and changes made by a skilled person in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims (9)

1. a signal amplifying circuit of an infrared grating alarm device, comprising an infrared encoding transmitting circuit of emission infrared light signal and an infrared decoding receiving circuit of decoding infrared light signal; it is characterized in that: also include being connected with infrared decoding receiving circuit for receiving infrared light Optical signal amplifier circuit for optical signal; The optical signal amplifying circuit includes a first-stage operational amplifier circuit that amplifies the received infrared light signal in the first stage, a filter circuit that performs frequency selection on the first-stage amplified infrared light signal, and a filter circuit that amplifies the infrared light signal in the first stage. A second-stage operational amplifier circuit for the second-stage amplification of the infrared light signal; the filter circuit includes a high-pass filter and a low-pass filter arranged in parallel. 2. The infrared grating alarm signal amplifier circuit according to claim 1, wherein the high-pass filter comprises at least two stages of high-pass filter circuits, and the low-pass filter comprises at least two stages of low-pass filter circuits . 3. The infrared grating alarm signal amplifier circuit of claim 1, wherein the first stage operational amplifier circuit comprises an infrared receiver tube DS1, a resistor R11, a capacitor C26, a resistor R57, a resistor R58, a first Amplifier U3A, resistor R41, resistor R46, resistor R45, capacitor C10 and capacitor C14; One end of the resistor R11 and the capacitor C26 is connected to the infrared receiving tube DS1, and the other end of the resistor R11 is grounded; the resistor R57 and the resistor R58 are arranged in parallel, and the other end of the capacitor C26, one end of the resistor R57 and the resistor R58 are connected in parallel. One end is connected to the same-direction input end of the first operational amplifier U3A, the other end of the resistor R58 is connected to the reference voltage, and the other end of the resistor R57 is grounded; One end of the resistor R45 is connected to the reverse input terminal of the first operational amplifier U3A, and the other end of the resistor R45 is grounded through the capacitor C10; one end of the resistor R46 is connected to the reverse input terminal of the first operational amplifier U3A, One end of the resistor R41 is connected to the output end of the first operational amplifier U3A, and the other ends of the resistor R46 and the resistor R41 are both grounded through the capacitor C14. 4. The infrared grating alarm signal amplifier circuit according to claim 3, wherein the first-stage operational amplifier circuit further comprises a capacitor C18 and a capacitor C15; the capacitor C18 is arranged in the first operational amplifier U3A. Between the non-inverting input terminal and the inverting input terminal; the capacitor C15 is set between the resistor R41 and the resistor R46. 5. The infrared grating alarm signal amplifier circuit according to claim 1, wherein the second-stage operational amplifier circuit comprises a first operational amplifier U3B, a resistor R29, a resistor R40, a resistor R44, a capacitor C4 and a capacitor C23; One end of the resistor R44 and the resistor R40 are both connected to the reverse input end of the first operational amplifier U3B, one end of the resistor R29 is connected to the output end of the first operational amplifier U3B, and the other end of the resistor R44 is grounded through the capacitor C23, The other ends of resistor R40 and resistor R29 are connected to ground through capacitor C4. 6. The infrared grating alarm signal amplifier circuit of claim 5, wherein the second-stage operational amplifier circuit further comprises a capacitor C17 and a capacitor C12; the capacitor C17 is arranged in the first operational amplifier U3B. Between the inverting input terminal and the non-inverting input terminal, the capacitor C12 is arranged between the resistor R40 and the resistor R29. 7. The infrared grating alarm signal amplifier circuit of claim 2, wherein the high-pass filter comprises a first-stage high-pass filter circuit composed of a capacitor C5, a resistor R30, and a capacitor C6, and a first-stage high-pass filter circuit composed of a capacitor C9, a resistor The second-stage high-pass filter circuit composed of R56 and capacitor C16; The low-pass filter includes a first-stage low-pass filter circuit composed of resistor R32, capacitor C7, capacitor C8, and resistor R31, and a second-stage low-pass filter circuit composed of resistor R39, capacitor C21, and resistor R54. 8. The infrared grating alarm signal amplifier circuit according to any one of claims 1-7, characterized in that it further comprises an LC filter circuit connected to the second-stage operational amplifier circuit. 9. A method for amplifying a signal of an infrared grating alarm, wherein the amplifying method uses the signal amplifying circuit according to any one of claims 1-8, and the amplifying method comprises: The infrared encoding transmitting circuit transmits the encoded infrared light signal, and the encoded infrared light signal is composed of the transceiver mode code + preamble code + start code + data code; The optical signal amplifying circuit receives the infrared light signal emitted by the infrared coding transmitting circuit, inputs the infrared light signal into the first-stage operational amplifier circuit for first-stage amplification, and inputs the first-stage amplified infrared light signal into the filter circuit Carry out frequency selection filling wave, input the infrared light signal after frequency selection filling wave into the second-stage operational amplifier circuit for second-stage amplification, and output the second-stage amplified infrared light signal; The infrared decoding receiving circuit receives the infrared light signal output by the optical signal amplifying circuit, and decodes the received infrared light signal according to the coding protocol.

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