A time identification device based on peak hold signal

Abstract

The present invention relates to the field of laser radar ranging technology and discloses a time identification device based on a peak hold signal. The device comprises a pre-signal amplification module, an automatic gain control module, a pulse peak hold module, an improved constant ratio timing identification module, a leading edge time identification module, a logic determination module, and a time measurement module. The pre-signal amplification module is connected to the automatic gain control module, the automatic gain control module is connected to the pulse peak hold module, the pulse peak hold module is connected to the improved constant ratio timing identification module and the leading edge time identification module, respectively, the improved constant ratio timing identification module is connected to the logic determination module, the leading edge time identification module is connected to the logic determination module, and the logic determination module is connected to the time measurement module. The present invention solves the problem of fixed delay caused by system operation and improves the laser radar ranging accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar ranging, and in particular to a moment identification device based on peak hold signals. Background Art

[0002] LiDAR (LiDAR) ranging is achieved by emitting a laser beam, which, after reflecting off a target object, forms an echo signal. After processing the signal, the distance and position of the target can be determined. In LiDAR based on the TOF (time of flight) principle, the timing detection accuracy of the echo pulse is a key factor affecting ranging accuracy. Currently, there are two main methods for detecting the timing of laser pulse echo signals: analog time identification and digital time identification. While digital time identification is more accurate than analog time identification, it has disadvantages such as high cost, complex circuitry, and strict application environment requirements.

[0003] The analog time identification method is greatly affected by the echo waveform of the pulsed laser. Since the laser signal transmission process is affected by factors such as atmospheric scattering attenuation, diffuse reflection from the obstacle surface, and the incident angle of the echo signal, the waveform of the conditioned pulse signal will change. If it is not processed in a certain way, the fluctuation of the comparator triggering time will become very large. Accordingly, a certain error will be generated during the time identification, which will ultimately affect the ranging accuracy.

[0004] According to existing research results, there are three main typical signal moment identification methods: the first is the zero-point detection method, which is an electric echo light pulse signal that undergoes photoelectric conversion and signal conditioning circuits. After the output amplified voltage pulse signal enters the high-pass capacitive filter circuit, the pulse waveform becomes an approximate sine wave, that is, the peak point of the pulse signal is converted into the zero point of the sine wave. The moment when the laser receives the pulse can be obtained through the zero-crossing detection circuit. However, since the signal will be greatly attenuated after passing through the high-pass capacitive filter circuit, it is easy to cause false triggering; the second is the leading edge moment identification method, also known as the direct comparison method, in which the echo pulse signal is compared with the device through a high-speed comparator. When the input signal is greater than the constant reference voltage amplitude, a trigger signal is generated instantaneously to trigger the counter to stop timing. However, due to the large change in the amplitude of the echo signal, a walking error is generated. The third method is the constant ratio timing identification method. The constant ratio timing identification method uses the principle that the rising edges of the two echo pulse signals have the same amplitude and the corresponding time remains unchanged. This moment is used as the threshold signal of the received pulse. The point of triggering the digital signal is only related to the constant proportion point of the leading edge, and has nothing to do with the amplitude or leading edge width of the signal. The constant ratio timing identification method has a strong anti-interference ability and can well avoid the drift error caused by the change in echo amplitude.

[0005] Therefore, the prior art still has some shortcomings. Summary of the Invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a time identification device based on a peak hold signal. The present invention makes targeted improvements and optimizations to address the above shortcomings. The identification method based on the peak hold signal and combined with constant ratio timing and leading edge timing has more accurate ranging accuracy compared to the traditional constant ratio timing method, thereby solving the above problems.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A time identification device based on a peak hold signal comprises a pre-signal amplification module, an automatic gain control module, a pulse peak hold module, an improved constant ratio timing identification module, a leading edge time identification module, a logic determination module and a time measurement module. The pre-signal amplification module is connected to the automatic gain control module, the automatic gain control module is connected to the pulse peak hold module, the pulse peak hold module is respectively connected to the improved constant ratio timing identification module and the leading edge time identification module, the improved constant ratio timing identification module is connected to the logic determination module, the leading edge time identification module is connected to the logic determination module, and the logic determination module is connected to the time measurement module.

[0009] Preferably, the pre-signal amplification module includes an APD detector unit and a transimpedance amplifier unit connected in sequence, and the transimpedance amplifier unit includes an OPA657 transimpedance amplifier, which is used to ensure distortion-free amplification of the echo signal while filtering out unnecessary noise signals and inputting the echo signal into the next-level automatic gain control module.

[0010] Preferably, the automatic gain control module includes a gain setting unit, a delay unit and a variable gain amplifier unit, the delay unit is connected to the gain setting unit and the variable gain amplifier unit respectively, and the gain setting unit is connected to the variable gain amplifier unit.

[0011] More preferably, the gain setting unit includes an operational amplifier OPA2625, a comparator TLV3501 and a resistor network.

[0012] Preferably, the pulse peak holding module includes a voltage buffer OPA2354, a voltage amplifier MAX436, a peak detection diode BAR74, a first resistor R1, a second resistor R2 and a capacitor C.

[0013] More preferably, the output end of the voltage amplifier MAX436 is connected to the input end of the peak detection diode BAR74, one path of the output end of the peak detection diode BAR74 is connected to the inverting input end of the voltage amplifier MAX436, and the other path is connected to the positive input end of the voltage buffer OPA2354; the capacitor C and the resistor R1 are connected in parallel, and their output ends are both grounded, and their input ends are connected to the output end of the peak detection diode BAR74; the output end of the voltage buffer OPA2354 is connected to the second resistor R2, and the output end of the second resistor R2 is connected to the inverting input end of the voltage buffer OPA2354.

[0014] Preferably, the improved constant ratio timing identification module includes a leading edge moment identification unit, a constant ratio timing identification unit and a first high-speed comparator circuit, the constant ratio timing identification unit is connected to the leading edge moment identification unit and the first high-speed comparator circuit respectively, the leading edge moment identification unit includes a second high-speed comparator circuit, the first high-speed comparator circuit is connected to the output end of the constant ratio timing identification unit, the second high-speed comparator circuit is connected to the input end of the constant ratio timing identification unit, and the output ends of both are connected to the logic judgment module.

[0015] More preferably, the constant ratio timing identification unit includes an attenuation inversion circuit, a delay circuit and an adder circuit. The pulse signal is input into the constant ratio timing identification unit and is divided into two signals that enter the attenuation inversion circuit and the delay circuit respectively. The attenuation inversion circuit and the delay circuit are respectively connected to the adder circuit.

[0016] Preferably, the time measurement module includes a TDC-GP22 timing unit and a single-chip microcomputer fitting calculation unit.

[0017] More preferably, the time measurement module obtains the flight time of the pulsed laser and thus obtains the measured distance; since there will be a certain delay deviation in the distance measurement, the single-chip microcomputer fitting calculation unit fits the measured distance and the actual distance to show a linear relationship, and the linear relationship formula is y=k*x+m, where k is the weight of the chip measurement data of the TDC-GP22 timing unit, m is the error compensation constant, x is the measured distance, and y is the actual distance.

[0018] Compared with the traditional constant ratio timing identification method, the present invention has the following main benefits:

[0019] The present invention, based on the combination of an automatic gain module, utilizes a peak hold circuit to better capture the amplitude of an echo narrow pulse, effectively reducing the jitter error caused by the amplitude wander effect and the rise time wander effect. The signal output by the peak hold first passes through a buffer to perform a certain shaping on the pulse waveform. The shaped signal undergoes attenuation inversion on one path and delay on the other path. The two signals are then input into an adder together for addition. The waveform output by the adder can further reduce the time jitter error. The initial moment identification signal STOP1 generated by the improved constant ratio timing identification module and the leading moment identification signal STOP2 generated by the leading moment identification module enter the logic AND gate for logical judgment to obtain a more accurate trigger signal. Finally, through the time measurement module, the single-chip microcomputer automatically fits and calculates the digital circuit's own jitter standard deviation for calibration, reducing the digital circuit's rising edge jitter error. At the same time, the root mean square is calculated to perform nonlinear error correction. The distance measurement accuracy can be significantly improved by the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0021] Figure 1 Schematic diagram of the overall module structure and flow of the peak hold signal timing identification device according to an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure and flow of the automatic gain control module according to an embodiment of the present invention;

[0023] Figure 3 This is a peak hold circuit diagram according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure and flow of the improved constant ratio timing identification module and logic determination module according to an embodiment of the present invention;

[0025] Figure 5 The figure is a schematic diagram of the structure and flow of the time measurement module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] A time identification device based on a peak hold signal is further described in detail below in conjunction with specific embodiments. These embodiments are only used for comparison and explanation purposes, and the present invention is not limited to these embodiments.

[0027] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", "top", "bottom", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0028] Example

[0029] See attached Figure 1-5 The present embodiment provides a time identification device based on a peak hold signal, comprising a pre-signal amplification module, an automatic gain control module, a pulse peak hold module, an improved constant ratio timing identification module, a leading edge time identification module, a logic determination module, and a time measurement module. The pre-signal amplification module is connected to the automatic gain control module, the automatic gain control module is connected to the pulse peak hold module, the pulse peak hold module is respectively connected to the improved constant ratio timing identification module and the leading edge time identification module, the improved constant ratio timing identification module is connected to the logic determination module, the leading edge time identification module is connected to the logic determination module, and the logic determination module is connected to the time measurement module.

[0030] Preferably, the pre-signal amplification module includes an APD detector unit and a transimpedance amplifier unit connected in sequence, and the transimpedance amplifier unit includes an OPA657 transimpedance amplifier, which is used to ensure distortion-free amplification of the echo signal while filtering out unnecessary noise signals and inputting the echo signal into the next-level automatic gain control module.

[0031] In this embodiment, the pre-signal amplification module adopts the form of transimpedance amplification, and the OPA657 integrated operational amplifier is used as the transimpedance amplifier of the receiving module. The main function of the transimpedance amplifier is to convert the weak photocurrent signal generated by the avalanche photodiode APD into a voltage pulse signal and amplify it. Since the echo signal received by the APD is related to factors such as the quality of the transmitted light beam, atmospheric attenuation, the reflection angle of the obstacle surface, and the spectral sensitivity of the detector itself, the receiving end is often prone to introduce a variety of noise signals, which may annihilate the useful echo signal after the subsequent multiple stages of amplification. The low-noise transimpedance amplifier circuit ensures that the echo signal is amplified without distortion while filtering out unnecessary noise signals and inputs them into the next-level automatic gain control module.

[0032] Preferably, the automatic gain control module includes a gain setting unit, a delay unit and a variable gain amplifier unit, the delay unit is connected to the gain setting unit and the variable gain amplifier unit respectively, and the gain setting unit is connected to the variable gain amplifier unit.

[0033] More preferably, the gain setting unit includes an operational amplifier OPA2625, a comparator TLV3501 and a resistor network.

[0034] The function of the automatic gain module is to generate an exponential gain to control the dynamic range of the echo amplitude. While taking into account that small signals at long distances can be detected, it also avoids the amplification saturation of signals at closer distances, so that the voltage amplitude of the output signal of the voltage-controlled amplifier circuit basically does not change with the target distance. The input signal can be processed in a relatively short time, so that the improved constant ratio timing identification module receives a signal with a smaller amplitude dynamic range.

[0035] The automatic gain control module consists of three main components: a gain setting unit, a delay unit, and a variable gain amplifier unit. The input signal to the automatic gain control module is split into two paths. One path enters the gain setting unit for signal amplitude detection, where the input signal's amplitude is compared with a standard threshold level and the quantized result is passed to the variable gain amplifier. The other path enters the delay unit, where variable gain amplification is performed based on the quantization result of the gain setting unit.

[0036] In this embodiment, the gain setting unit is composed of an operational amplifier OPA2625, a comparator TLV3501 and a resistor network for setting the threshold level. The voltage follower function of the operational amplifier is used to isolate the input echo pulse signal. The comparator compares the input signal with the set threshold level and sets the gain at one time after amplitude comparison, thereby completing the division of signal energy and gain setting. The delay unit is formed by two OPA2652s in cascade, and the peripheral circuit is connected with resistors and capacitors. The delay time can be controlled within the required time unit by adjusting the corresponding values ​​of the resistors and capacitors. The variable gain amplifier unit is composed of discrete components such as operational amplifiers and field effect transistors. The high-speed on-off setting of the MOS tube and the parallel resistance value of the inverting end of the operational amplifier are used to control the circuit to achieve different gain amplifications. That is, after receiving the gain setting signal, the variable gain amplifier is input to control the pulse signal amplitude within the optimal input range of the improved constant ratio timing identification module. The automatic gain control module controls the gain by comparing and quantizing the voltage amplitude, thereby realizing automatic gain control. The block diagram of the automatic gain control module is as follows: Figure 2 shown.

[0037] Preferably, the pulse peak holding module includes a voltage buffer OPA2354, a voltage amplifier MAX436, a peak detection diode BAR74, a first resistor R1, a second resistor R2 and a capacitor C.

[0038] More preferably, the output end of the voltage amplifier MAX436 is connected to the input end of the peak detection diode BAR74, one path of the output end of the peak detection diode BAR74 is connected to the inverting input end of the voltage amplifier MAX436, and the other path is connected to the positive input end of the voltage buffer OPA2354; the capacitor C and the resistor R1 are connected in parallel, and their output ends are both grounded, and their input ends are connected to the output end of the peak detection diode BAR74; the output end of the voltage buffer OPA2354 is connected to the second resistor R2, and the output end of the second resistor R2 is connected to the inverting input end of the voltage buffer OPA2354.

[0039] The main function of the pulse peak hold circuit module is to capture the peak voltage of the output signal of the automatic gain control module and hold it for a certain period of time.

[0040] In this embodiment, the pulse peak hold circuit is composed of a voltage buffer OPA2354, a voltage amplifier MAX436, a peak detection diode BAR74, a charging circuit, and a discharging circuit. The voltage amplifier uses a MAX436 with a gain of 2, which amplifies the voltage difference between the input voltage and the output voltage and outputs a voltage signal. The positive end is connected to the output signal of the automatic gain control module to amplify and buffer the input signal to improve the driving ability and anti-interference ability. The peak hold circuit diagram is shown in FIG. Figure 3 As shown. The output of the voltage amplifier MAX436 is connected to the input of the peak detection diode BAR74. One output of the peak detection diode BAR74 is connected to the inverting terminal of the voltage amplifier MAX436, and the other output is connected to the positive input of the voltage buffer OPA2354. The holding capacitor C and resistor R1 in the charging circuit are connected in parallel, with their outputs both grounded and their inputs connected to the output of the peak detection diode BAR74. The capacitance and resistance of the holding capacitor C and resistor R1 should not be set too small, as such a small value will result in an excessively large droop rate of the peak hold signal. The inverting input of the voltage buffer OPA2354 and the buffer resistor R2 of the voltage buffer OPA2354 are connected in series and then connected to the inverting terminal of the voltage buffer OPA2354. The function of the voltage buffer is to buffer the output signal, further reducing the droop rate.

[0041] Preferably, the improved constant ratio timing identification module includes a leading edge moment identification unit, a constant ratio timing identification unit and a first high-speed comparator circuit, the constant ratio timing identification unit is connected to the leading edge moment identification unit and the first high-speed comparator circuit respectively, the leading edge moment identification unit includes a second high-speed comparator circuit, the first high-speed comparator circuit is connected to the output end of the constant ratio timing identification unit, the second high-speed comparator circuit is connected to the input end of the constant ratio timing identification unit, and the output ends of both are connected to the logic judgment module.

[0042] More preferably, the constant ratio timing identification unit includes an attenuation inversion circuit, a delay circuit and an adder circuit. The pulse signal is input into the constant ratio timing identification unit and is divided into two signals that enter the attenuation inversion circuit and the delay circuit respectively. The attenuation inversion circuit and the delay circuit are respectively connected to the adder circuit.

[0043] In this embodiment, the improved constant fraction timing identification module consists of a leading edge moment identification unit, a constant fraction timing identification unit, and a first high-speed comparator circuit. Because the high-speed comparator of the improved constant fraction timing identification module can be interfered with by the input noise of the APD and circuit noise, any small-amplitude noise pulse will cause the discriminator to falsely trigger. Therefore, a leading edge moment identification unit is required to solve the system's false triggering problem by setting a fixed threshold. The leading edge moment identification unit includes a second high-speed comparator TLV3501.

[0044] First, the pulse signal output by the pulse peak hold module via the voltage buffer is split into two paths. One pulse signal is connected to the positive input of the second high-speed comparator. By selecting an appropriate threshold, it eliminates timing misjudgments that may be caused by noise, thereby reducing the false alarm probability of the lidar ranging system. The other pulse signal is input into the constant ratio timing discrimination unit.

[0045] In this embodiment, the attenuation portion of the attenuated inverting circuit is implemented in the form of a series resistor divider, and the inverting portion is composed of a voltage feedback operational amplifier OPA2652 and a peripheral circuit, which performs phase flipping on the attenuated signal without loss; the attenuated inverted signal is sent to the second input terminal of the positive input of the adder circuit; the delay circuit is composed of a first-level operational amplifier OPA2652 combined with a resistor and a capacitor to form a low-pass filter to achieve a certain delay of the pulse signal, and the delayed signal is sent to the first input terminal of the positive input of the adder circuit; the adder circuit is used to add the attenuated inverted peak hold signal and the delayed positive phase peak hold signal as a constant ratio in-phase peak hold output signal, the output signal enters the positive input terminal of the first high-speed comparator and is compared with a set threshold reference voltage. When the input signal is higher than the set fixed threshold, the first high-speed comparator is triggered to generate a high level; under the action of the peak hold circuit, the output of the adder circuit can produce a shorter rising edge.

[0046] The logic judgment module is composed of a logic AND gate unit. The output signals of the upper leading edge moment identification unit and the first high-speed comparator circuit are simultaneously input into the logic AND gate unit. When the output signals of both are high, the logic AND gate is triggered, and the output signals of the two are ANDed. The time point of the rising edge of the output signal of the logic AND gate unit is the final signal moment identification point, that is, the timing logic pulse STOP signal. The rising edge of the moment identification signal is short and stable, which again achieves the purpose of reducing the walking error. The block diagram of the improved constant ratio timing identification module and the logic judgment module is shown in FIG. Figure 4 shown.

[0047] Preferably, the time measurement module includes a TDC-GP22 timing unit and a single-chip microcomputer fitting calculation unit.

[0048] More preferably, the time measurement module obtains the flight time of the pulsed laser and thus obtains the measured distance; since there will be a certain delay deviation in the distance measurement, the single-chip microcomputer fitting calculation unit fits the measured distance and the actual distance to show a linear relationship, and the linear relationship formula is y=k*x+m, where k is the weight of the chip measurement data of the TDC-GP22 timing unit, m is the error compensation constant, x is the measured distance, and y is the actual distance.

[0049] In this embodiment, the time measurement module is implemented through a single-chip microcomputer (MCU) terminal fitting calculation, consisting of a TDC-GP22 timing unit and a MCU fitting calculation unit. The MCU transmits a laser pulse, which is simultaneously input into the TDC-GP22's START port, triggering time measurement. Once the reflected pulse from the object reaches the APD, a STOP signal is generated to the TDC-GP22, completing the time measurement process. The time between the START and STOP pulses is accurately recorded by the TDC-GP22 and used to calculate the distance between the measured object and the transmitter. The MCU configures the TDC-GP22's registers and controls the time measurement. The time measurement result is then transmitted back to the MCU for precise distance calculation.

[0050] The TDC-GP22 timing unit consists of a TDC timing chip (TDC-GP22) from ACAM and an STM32F103ZET6 microcontroller. This chip measures time in two ranges, with measurement mode using range 1. Within this range, the typical resolution reaches 90 ps. The TDC-GP22 chip's internal architecture includes a temperature unit, a low-power clock control unit, a pulse generation unit, a register configuration unit, an analog signal processing module, a time-to-digital converter (TDC), a data processing module, and an SPI communication interface. The STM32F103ZET6 microcontroller's primary function is to provide a trigger pulse signal for the laser driver circuit. This, along with the time identification signal generated by the logic decision module, is input into the TDC-GP22 timing unit to determine the time of flight of the pulsed laser and, therefore, the measured distance. Due to a certain delay in the system's distance measurement, the measured distance deviates from the actual distance. This deviation can be fitted using MATLAB. The fitting result shows that the system measured distance is linearly related to the actual distance. The linear relationship is y=k*x+m, where k is the weight of the TDC-GP22 chip measurement data, m is the error compensation constant, x is the measured distance, and y is the actual distance. Finally, the fitting function is burned into the microcontroller to achieve accurate automatic fitting distance measurement, which greatly reduces the walking error. The block diagram of the time measurement module is shown in the figure. Figure 5 shown.

[0051] The above-mentioned embodiments of the present invention improve the signal moment identification method. Compared with the existing traditional timing scheme, the present invention can achieve high-accuracy signal moment identification of pulse signals, solve the measurement error problem caused by the rise time wander effect in the traditional constant ratio timing method, and reduce the walking error in the ranging system; effectively prevent false triggering that may be caused by diffuse reflection or other light signals; solve the shaking error caused by the amplitude wander effect and the rise time wander effect, and improve the pulse laser ranging accuracy; solve the fixed delay problem caused by system operation, and improve the lidar ranging accuracy.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A time identification device based on peak hold signal, characterized in that: It includes a pre-signal amplification module, an automatic gain control module, a pulse peak holding module, an improved constant ratio timing identification module, a leading edge moment identification module, a logic determination module and a time measurement module, wherein the pre-signal amplification module is connected to the automatic gain control module, the automatic gain control module is connected to the pulse peak holding module, the pulse peak holding module is connected to the improved constant ratio timing identification module and the leading edge moment identification module respectively, the improved constant ratio timing identification module is connected to the logic determination module, the leading edge moment identification module is connected to the logic determination module, and the logic determination module is connected to the time measurement module; The improved constant fraction timing identification module includes a leading edge moment identification unit, a constant fraction timing identification unit and a first high-speed comparator circuit, wherein the constant fraction timing identification unit is connected to the leading edge moment identification unit and the first high-speed comparator circuit respectively, and the leading edge moment identification unit includes a second high-speed comparator circuit, wherein the front ends of the first high-speed comparator circuit and the second high-speed comparator circuit are both connected to the constant fraction timing identification unit, and the output ends thereof are both connected to the logic determination module; The pulse peak holding module includes a voltage buffer OPA2354, a voltage amplifier MAX436, a peak detection diode BAR74, a first resistor R1, a second resistor R2 and a capacitor C; The pulse signal output by the pulse peak holding module through the voltage buffer is divided into two paths, one of which is connected to the positive input terminal of the second high-speed comparator. By selecting an appropriate threshold, the time misjudgment that may be caused by noise is eliminated, thereby reducing the false alarm probability of the laser radar ranging system. The other pulse signal is input into the constant ratio timing identification unit.

2. The time identification device based on the peak hold signal according to claim 1, characterized in that: The pre-signal amplification module includes an APD detector unit and a transimpedance amplifier unit connected in sequence. The transimpedance amplifier unit includes an OPA657 transimpedance amplifier, which is used to ensure distortion-free amplification of the echo signal while filtering out unnecessary noise signals and inputting the echo signal into the next-level automatic gain control module.

3. The time identification device based on the peak hold signal according to claim 1, characterized in that: The automatic gain control module includes a gain setting unit, a delay unit and a variable gain amplifier unit. The delay unit is connected to the gain setting unit and the variable gain amplifier unit respectively. The gain setting unit is connected to the variable gain amplifier unit.

4. The time identification device based on the peak hold signal according to claim 3, characterized in that: The gain setting unit includes an operational amplifier OPA2625, a comparator TLV3501 and a resistor network.

5. The time identification device based on the peak hold signal according to claim 4, characterized in that: The output end of the voltage amplifier MAX436 is connected to the input end of the peak detection diode BAR74. One path of the output end of the peak detection diode BAR74 is connected to the inverting input end of the voltage amplifier MAX436, and the other path is connected to the positive input end of the voltage buffer OPA2354. The capacitor C and the resistor R1 are connected in parallel, and their output ends are both grounded, and their input ends are connected to the output end of the peak detection diode BAR74. The output end of the voltage buffer OPA2354 is connected to the second resistor R2, and the output end of the second resistor R2 is connected to the inverting input end of the voltage buffer OPA2354.

6. The time identification device based on the peak hold signal according to claim 1, characterized in that: The constant ratio timing identification unit includes an attenuation inversion circuit, a delay circuit and an adder circuit. A pulse signal is input into the constant ratio timing identification unit and is divided into two signals that enter the attenuation inversion circuit and the delay circuit respectively. The attenuation inversion circuit and the delay circuit are respectively connected to the adder circuit.

7. The time identification device based on the peak hold signal according to claim 1, characterized in that: The time measurement module includes a TDC-GP22 timing unit and a single chip microcomputer fitting calculation unit.

8. The time identification device based on the peak hold signal according to claim 7, characterized in that: After the time measurement module obtains the flight time of the pulsed laser, it obtains the measured distance. Since there will be a certain delay deviation in the distance measurement, the microcontroller fitting calculation unit fits the measured distance and the actual distance to show a linear relationship. The linear relationship formula is y=k*x+m, where k is the weight of the chip measurement data of the TDC-GP22 timing unit, m is the error compensation constant, x is the measured distance, and y is the actual distance.

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