Sunlight false alarm adaptive suppression circuit suitable for laser range finder

Abstract

The utility model discloses a sunlight false alarm self-adaptive suppression circuit suitable for a laser range finder, which comprises a receiving amplification circuit, an analog-to-digital conversion circuit, a main control circuit, a gain control circuit and a time-to-digital conversion circuit, and is characterized in that the receiving amplification circuit converts a current signal of an avalanche transistor into an analog voltage signal and sends the analog voltage signal to the analog-to-digital conversion circuit; the analog-to-digital conversion circuit shapes the pre-stage signal into a digital level signal and sends the digital level signal to the main control circuit; the main control circuit detects a preceding-stage signal and then feeds back a control signal to the gain control circuit, and the gain control circuit adjusts the amplification factor of the receiving amplification circuit to form closed-loop control; the input of the time-to-digital conversion circuit is connected with the analog-to-digital conversion circuit, and the output is connected with the main control circuit for calculating the ranging information. According to the utility model, laser emission is not needed in the feedback acquisition process, only signal logic judgment is needed, and distance measurement is carried out after noise accords with a preset value; sunlight interference can be identified, self-adaptive adjustment is carried out, and generation of sunlight false alarm is inhibited.

Description

Technical Field

[0001] The utility model relates to the technical field of laser optoelectronics, and relates to a laser ranging signal processing circuit, in particular to a sunlight false alarm adaptive suppression circuit applicable to a laser rangefinder. Background Art

[0002] Laser technology is widely used in the field of laser ranging. The laser beam has concentrated energy and a small divergence angle, and can achieve accurate long-distance target measurement. Laser ranging can use a relatively wide band range, generally 900nm - 1600nm in the near-infrared region. When designing the optical system, in order to avoid interference from ambient light (such as sunlight, lamp light, etc.), a filter is added to the optical receiving system to narrow the optical band range that the optical receiving system can receive in the ranging system, thereby achieving suppression of ambient light interference. However, sunlight contains light of all bands, and the filter cannot completely filter out sunlight during actual ranging, so there will still be false alarm errors. When laser ranging is applied to an airborne pod or ranging for an air target, the smaller the angle with the sun, the stronger the sunlight, and the more false alarm situations will occur.

[0003] Moreover, sunlight false alarms cause great interference to the application of laser ranging in some important projects. Although the existing technology can greatly reduce the false alarm probability through optical filter design technology, it cannot completely solve the false alarm problem. In view of this, an adaptive circuit applicable to a laser rangefinder that can solve the sunlight false alarm problem is needed. Summary of the Utility Model

[0004] In view of this, to solve the above deficiencies of the existing technology, the purpose of the present utility model is to propose a sunlight false alarm adaptive suppression circuit applicable to a laser rangefinder, which can identify sunlight interference, make adaptive adjustments, suppress the generation of sunlight false alarms, and improve the applicability of ranging products.

[0005] To achieve the above purpose, the technical solution adopted by the present utility model is:

[0006] A sunlight false alarm adaptive suppression circuit applicable to a laser rangefinder includes a receiving and amplifying circuit, an analog-to-digital conversion circuit, a main control circuit, a gain control circuit, and a time-to-digital conversion circuit;

[0007] The receiving and amplifying circuit is used to convert the current signal generated by the avalanche tube into an analog voltage signal, and the output end of the receiving and amplifying circuit is connected to the analog-to-digital conversion circuit;

[0008] The analog-to-digital conversion circuit is used to shape the received analog voltage signal into a digital level signal, and the output end of the analog-to-digital conversion circuit is divided into two paths, one path is directly connected to the main control circuit;

[0009] Another path of the time-to-digital conversion circuit is connected to the main control circuit. The time-to-digital conversion circuit is used to convert the time information of the signal into a data string and transmit it to the main control circuit in parallel and serial form.

[0010] The main control circuit is used to detect the pre-stage signal, discriminate it, and then feedback the control signal to the gain control circuit. The output end of the gain control circuit is connected to the receiving and amplifying circuit. It is also used to calculate the data information of the digital conversion circuit to complete ranging.

[0011] Further, the receiving and amplifying circuit includes a transimpedance amplifier and a voltage-controlled gain post-stage amplifier circuit, which converts the current signal generated by the avalanche tube into a voltage signal. The voltage-controlled gain amplifier adjusts the amplification factor according to the gain voltage output by the gain control circuit.

[0012] Further, the main control circuit completes signal noise acquisition and feedback control to keep the total time within the millisecond level.

[0013] Further, the time-to-digital conversion circuit transmits information to the main control circuit through SPI communication.

[0014] Advantages of the present utility model:

[0015] The adaptive suppression circuit of the present utility model collects sunlight noise by the main controller when it is static, and quickly feeds back and adjusts the gain control circuit to adjust the amplification parameters until the noise meets the preset value, suppressing sunlight noise and completing ranging without false alarms. Further, the receiving circuit converts the current signal gain generated by the avalanche tube into a voltage signal, and the amplification gain is determined by the voltage output by the gain control circuit. The acquisition and feedback process do not require laser emission, only signal logic judgment is needed.

[0016] By feedback regulation to suppress noise, after the parameters are adaptively adjusted, the time-to-digital conversion is started. The main controller reads the time information and converts it into a ranging distance to complete the ranging process. The entire feedback process is controlled within the millisecond level and will not affect the high-frequency ranging state of laser ranging. Description of the drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 It is the schematic diagram of the adaptive suppression circuit of the present utility model;

[0019] Figure 2 It is the schematic diagram of the receiving and amplifying circuit in the embodiment;

[0020] Figure 3 is the schematic diagram of the analog-to-digital conversion circuit in the embodiment;

[0021] Figure 4 is the schematic diagram of the main control circuit in the embodiment;

[0022] Figure 5 is the schematic diagram of the time-to-digital conversion circuit in the embodiment;

[0023] Figure 6 is the schematic diagram of the gain control circuit in the embodiment. Specific Embodiments

[0024] Specific embodiments are given below to further clearly, completely, and detailedly illustrate the technical solution of the present invention. This embodiment is the best embodiment based on the technical solution of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0025] Embodiment 1

[0026] A sunlight false alarm adaptive suppression circuit applicable to a laser rangefinder, as shown in Figure 1 includes a receiving and amplifying circuit, an analog-to-digital conversion circuit, a main control circuit, a gain control circuit, and a time-to-digital conversion circuit;

[0027] The receiving and amplifying circuit is used to convert the current signal generated by the avalanche tube into an analog voltage signal, and the output end of the receiving and amplifying circuit is connected to the analog-to-digital conversion circuit;

[0028] The analog-to-digital conversion circuit is used to shape the received analog voltage signal into a digital level signal. The output end of the analog-to-digital conversion circuit is divided into two paths. One path is directly connected to the main control circuit as the basis for feedback modulation; the other path is connected to the main control circuit through the time-to-digital conversion circuit;

[0029] The time-to-digital conversion circuit is used to convert the time information of the signal into a data string containing distance information and transmit it to the main control circuit for calculating the ranging information;

[0030] The main control circuit is used to detect the pre-stage signal, judge, and then feedback the control signal to the gain control circuit. The output end of the gain control circuit is connected to the receiving and amplifying circuit to convert the digital signal output by the main control circuit into an analog signal applicable to the receiving circuit, playing a bridging role to limit the amplification factor of the receiving and amplifying circuit; the main control circuit is also used to solve the data information of the digital conversion circuit to complete ranging.

[0031] Further, the receiving and amplifying circuit includes a transimpedance amplifier and a voltage-controlled gain post-amplification circuit, which convert the current signal generated by the avalanche diode into a voltage signal. The voltage-controlled gain amplifier adjusts the amplification factor according to the gain voltage output by the gain control circuit.

[0032] The amplifying circuit includes resistors R1 to R4, capacitors C1 to C9, a high-frequency resistor RF1, an amplifier U1, an operational amplifier chip U2, and an avalanche diode D1. The signal of the avalanche diode D1 is outputted successively through the amplifier U1 and the operational amplifier chip U2 and sent to the output end of the analog-to-digital conversion circuit.

[0033] The time-to-digital conversion circuit includes capacitors C18 to C25, a resonator Y2, a resonator Y3, and a high-precision time measurement chip U6. After the digital level signal of the analog-to-digital conversion circuit is calculated and converted by the precision time measurement chip U6, it is outputted to the input end of the main control circuit.

[0034] Further, the time-to-digital conversion circuit transmits information to the main control circuit through SPI communication.

[0035] The main control circuit includes a minimum single-chip microcomputer system U4, which can detect whether there is noise interference and control the gain voltage at the same time, adjust the amplification factor of the receiving circuit. After the parameter adjustment is completed, it emits a laser pulse and resolves the data information of the digital conversion circuit to complete the ranging.

[0036] Further, the main control circuit completes signal noise acquisition and feedback control with the total time within the ms level.

[0037] The gain control circuit includes a digital-to-analog converter U5, which receives the control signal sent by the minimum single-chip microcomputer system U4 and outputs a gain control signal.

[0038] Specifically, the analog-to-digital conversion circuit uses a comparator. When the signal or noise is greater than the set threshold, it will output a digital signal to avoid power supply noise interference.

[0039] The working principle is as follows:

[0040] After the laser ranging circuit is powered on, it starts initialization preparation, receives the output noise state of the receiving and amplifying circuit, converts the current signal generated by the avalanche tube D1 into a voltage signal AI_SIG through gain conversion, and sends the voltage signal AI_SIG to the analog-to-digital conversion circuit to convert it into a digital level signal TEST_SIG. The digital level signal TEST_SIG is directly input to the main control circuit. The main control circuit completes signal noise acquisition and feedback-controls a control signal to the gain control circuit, converts the digital signal of the main control circuit into an analog voltage and sends it to the receiving and amplifying circuit, controls the gain multiple of the receiving and amplifying circuit, and makes the amplifying circuit in a noise-compliant and interference-free state that meets the requirements of analog-to-digital conversion. After detecting and adjusting the reasonable amplification multiple multiple times, the ranging process starts; the entire feedback process is completed within several ms and does not affect the laser ranging frequency;

[0041] A laser pulse is emitted. The analog signal received by the receiving and amplifying circuit is converted into a digital signal through the analog-to-digital conversion circuit. The digital signal converts the time information of the two signals, namely the digital level signal TEST_SIG and the start signal START, into a data string containing distance information through the time-to-digital conversion circuit and transmits it to the main control circuit. The main control circuit calculates the data information of the digital conversion circuit to complete ranging.

[0042] In summary, for the sunlight false alarm adaptive suppression circuit applicable to a laser rangefinder of the present utility model, the main controller collects sunlight noise, quickly feeds back and adjusts the gain control circuit, and adjusts the amplification parameters, which can effectively identify sunlight interference, make adaptive adjustments, suppress the generation of sunlight false alarms, and improve the applicability of ranging products.

[0043] The foregoing has shown and described the main features, basic principles, and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will also have various changes and improvements according to actual situations, and these changes and improvements all fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. A sunlight false alarm adaptive suppression circuit suitable for laser rangefinder, characterized in that: It includes a receiving amplifier circuit, an analog-to-digital conversion circuit, a main control circuit, a gain control circuit and a time-to-digital conversion circuit; The receiving amplifier circuit is used to convert the current signal generated by the avalanche tube into an analog voltage signal, and the output end of the receiving amplifier circuit is connected to the analog-to-digital conversion circuit; The analog-to-digital conversion circuit is used to reshape the received analog voltage signal into a digital level signal. The output end of the analog-to-digital conversion circuit is divided into two paths, one of which is directly connected to the main control circuit; the other is connected to the main control circuit via a time-to-digital conversion circuit. The time-to-digital conversion circuit is used to convert the time information of the signal into a data string and transmit it to the main control circuit; The main control circuit is used to detect the front-stage signal and then feed back the control signal to the gain control circuit, the output end of the gain control circuit is connected to the receiving amplifier circuit; it is also used to solve the data information of the digital conversion circuit to complete the distance measurement.

2. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 1, characterized in that: The receiving amplifier circuit includes a transimpedance amplifier and a voltage-controlled gain post-amplifier circuit, which converts the current signal generated by the avalanche tube into a voltage signal. The voltage-controlled gain amplifier adjusts the amplification factor according to the gain voltage output by the gain control circuit.

3. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 1, characterized in that: The amplifying circuit includes resistors R1 to R4, capacitors C1 to C9, high-frequency resistor RF1, amplifier U1, operational amplifier chip U2 and avalanche tube D1. The signal of avalanche tube D1 is outputted via amplifier U1 and operational amplifier chip U2 in sequence and sent to the output end of the analog-to-digital conversion circuit.

4. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 1, characterized in that: The total time for the main control circuit to complete signal noise acquisition and feedback control is within ms level.

5. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 4, characterized in that: The main control circuit includes a single chip microcomputer minimum system, which detects whether there is noise interference and controls the gain voltage at the same time.

6. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 1, characterized in that: The analog-to-digital conversion circuit adopts a comparator.

7. The sunlight false alarm adaptive suppression circuit suitable for laser rangefinder according to claim 1, characterized in that: The time-to-digital conversion circuit transmits information to the main control circuit via SPI communication.

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