A dynamic threshold adjustment method for semi-active laser seeker

Abstract

The present invention belongs to the field of laser technology, and specifically discloses a dynamic threshold adjustment method suitable for a laser semi-active seeker. After the seeker intercepts a target, the target signal energy increases rapidly as the distance between the missile and the target approaches. At this time, the seeker performs dynamic gain adjustment on the signal strength through a built-in programmable gain amplifier. According to the gain parameter G at this time, the calculated detection threshold V'0 is corrected again as the detection threshold at the current moment, thereby achieving the purpose of adjusting the signal judgment threshold, improving the signal-to-noise ratio, and improving the measurement accuracy. The method dynamically adjusts the detection threshold according to the characteristics of the environmental background and the working state during the work of the seeker, improves the reliability of the seeker, reduces the false alarm rate, ensures the seeker's detection of effective signals, accurately obtains the receiving time and amplitude of the laser signal, and improves the overall performance of the seeker.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a dynamic threshold adjustment method for a laser semi-active seeker. Background Art

[0002] The laser semi-active seeker is an important component of laser-guided weapons, and its functions and performance will directly affect the combat performance of guided weapons. When the laser seeker is working, the laser illuminator first emits a laser beam to the target, and then uses the laser detector to receive the laser signal returned by the target diffuse reflection. When the detector output signal is greater than the set threshold, it is considered that there is a signal trigger, and then the target is identified and the target is detected. However, in the actual working environment, the ambient background light, such as sunlight and ground stray light, will affect the detector output signal. When the detector output caused by the ambient background light exceeds the set threshold, it will interfere with the interception and identification of the target signal by the seeker, causing the seeker to false alarm or fail to identify the target normally. If the initial threshold is set too high, the detection sensitivity of the seeker will be reduced, affecting the maximum effective range and reducing the combat performance. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a dynamic threshold adjustment method suitable for a laser semi-active seeker. The method can dynamically adjust the detection threshold according to the characteristics of the environmental background and the working state during the operation of the seeker, thereby improving the reliability of the seeker and reducing the false alarm rate, while ensuring the seeker's detection of effective signals, accurately obtaining the receiving time and amplitude of the laser signal, and improving the overall performance of the seeker.

[0004] The technical solution of the present invention is a dynamic threshold adjustment method applicable to a laser semi-active guidance head, and the specific steps are as follows:

[0005] Step (1) After the seeker starts working, it first performs predetermined parameter settings, such as setting the initial threshold V0, the initial gain G0, and the code pattern period T0;

[0006] Step (2) Subsequently, the energy value detected by the current detector is detected by the built-in high-speed AD acquisition circuit of the circuit part at a fixed period of 5ms, and the energy value detected by the detector is processed by a second-order Butterworth low-pass filter algorithm. The processed data is used as the background signal V of the current working environment of the seeker. i ;

[0007] Step (3) Before the seeker starts searching for the target, it does not respond to the trigger signal. At this time, the initial threshold V0 is combined with the background signal V detected in step (2) i Add them together to form the detection threshold V′0 at the current moment, that is, V′0=V0+V i, thereby achieving the purpose of suppressing the ambient background light, improving the reliability of the seeker and reducing the false alarm rate;

[0008] Step (4) After the seeker intercepts the target, the target signal energy increases rapidly as the distance between the missile and the target decreases. At this time, the seeker dynamically adjusts the signal strength through the built-in programmable gain amplifier. According to the gain parameter G at this time, the detection threshold V′0 calculated in step (3) is corrected again, that is, V″0=f(G)×V′0=f(G)×(V0+V i ) is used as the detection threshold at the current moment, thereby achieving the purpose of adjusting the signal judgment threshold, improving the signal-to-noise ratio, and improving the measurement accuracy.

[0009] The method dynamically adjusts the detection threshold according to the characteristics of the environmental background and working status during the operation of the seeker, thereby improving the reliability of the seeker and reducing the false alarm rate, while ensuring the seeker's detection of effective signals, accurately obtaining the receiving time and amplitude of the laser signal, and improving the overall performance of the seeker.

[0010] The beneficial effects of the present invention are:

[0011] (1) It can effectively reduce the impact of background ambient light such as sunlight and stray light on the detection of the seeker, improve the reliability of the seeker, and at the same time maximize the detection sensitivity of the seeker;

[0012] (2) During flight, the current threshold is adjusted in real time according to the seeker gain, so that the laser signal reception time and amplitude can be accurately obtained, while the detection signal-to-noise ratio is improved, thereby improving the overall performance of the seeker. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural principle block diagram of the circuit of the present invention.

[0014] Figure 2 It is a flowchart of the dynamic threshold adjustment process of the present invention. DETAILED DESCRIPTION

[0015] The structure, process and working principle of the present invention are further described in detail below in conjunction with the drawings and embodiments.

[0016] A dynamic threshold adjustment method for a laser semi-active seeker, the circuit structure diagram is as follows Figure 1 As shown, the circuit can convert optical signals into electrical signals and perform signal conditioning, complete signal acquisition, resolution and dynamic threshold adjustment, and output the resolved target information to the host computer.

[0017] The circuit specifically includes: (1) a laser four-quadrant detector component (SPD046), which completes the photoelectric conversion of the laser signal and outputs a four-quadrant voltage; (2) a high-gain variable gain amplifier (AD8336), which amplifies and conditions the weak voltage signal output by the laser four-quadrant detector; (3) a wave gate selection circuit, which realizes the wave gate control of the circuit analog channel; (4) a four-way summing circuit (AD8062ARM), which sums the four-quadrant voltage for back-end threshold comparison; (5) a sample-and-hold circuit (SMP04ES), which holds the four-quadrant voltage for back-end AD acquisition; (6) a time discrimination circuit (TLV3051), which sums the four-quadrant voltage The voltage signal after the sum is compared with the preset threshold value, and after the comparison, it is converted into a digital signal using a D flip-flop to obtain a trigger signal for moment identification; (7) a high-speed AD acquisition circuit (AD7606B) to acquire the four-quadrant voltage signal after the retention; (8) a digital-to-analog conversion circuit (AD5722) to realize the digital-to-analog conversion of the gain of the variable gain amplifier and the signal comparison threshold; (9) a processor circuit (DSP28377D) to realize data processing, communication and state control; (10) a power supply circuit to realize the conversion from external power supply to internal voltage, and convert the 28V input power supply into the power output required for the operation of each subsystem and device.

[0018] The corresponding dynamic threshold adjustment method, the flow chart is as follows Figure 2 The specific steps are as follows:

[0019] (1) After the seeker starts working, it first sets the preset parameters, such as the initial threshold V0, initial gain G0, and pattern period T0;

[0020] (2) Subsequently, the energy value detected by the current detector is detected by the built-in high-speed AD acquisition circuit of the circuit part at a fixed period of 5ms, and the energy value detected by the detector is processed using the second-order Butterworth low-pass filter algorithm. The processed data is used as the background signal V of the current working environment of the seeker. i ;

[0021] (3) Before the seeker starts searching for the target, it does not respond to the trigger signal. At this time, the initial threshold V0 is combined with the background signal V detected in step (2) i Add them together to form the detection threshold V′0 at the current moment, that is, V′0=V0+V i , thereby achieving the purpose of suppressing the ambient background light, improving the reliability of the seeker and reducing the false alarm rate;

[0022] (4) After the seeker intercepts the target, the target signal energy increases rapidly as the distance between the missile and the target decreases. At this time, the seeker dynamically adjusts the signal strength through the built-in programmable gain amplifier. According to the gain parameter G at this time, the detection threshold V′0 calculated in step (3) is corrected again, that is, V″0=f(G)×V′0=f(G)×(V0+V i ) is used as the detection threshold at the current moment, thereby achieving the purpose of adjusting the signal judgment threshold, improving the signal-to-noise ratio, and improving the measurement accuracy.

[0023] The function of the laser semi-active seeker is to receive the laser energy returned by the diffuse reflection of the target, intercept, identify, track the target signal, and output the target position information. Under normal circumstances, when the detector output signal is greater than the set threshold, it is considered that there is a signal trigger, and the target is identified immediately. However, in the actual working environment, the ambient background light, especially the sunlight, will affect the detector output signal. When it exceeds the set threshold, it will interfere with the interception and identification of the target signal by the seeker; at the same time, during the flight of the seeker, the change in signal strength also has different requirements for the threshold setting. The present invention dynamically adjusts the detection threshold according to the characteristics of the environmental background and the working state during the operation of the seeker, improves the reliability of the seeker, reduces the false alarm rate, and ensures the detection of the effective signal by the seeker, accurately obtains the receiving time and amplitude of the laser signal, and improves the overall performance of the seeker.

[0024] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A dynamic threshold adjustment method suitable for a laser semi-active guidance head, characterized in that The specific steps of the dynamic threshold adjustment method are as follows: Step (1) After the seeker starts working, first set the preset parameters and set the initial threshold , initial gain , and the pattern period ; Step (2) Subsequently, the energy value detected by the current detector is detected by the built-in high-speed AD acquisition circuit of the circuit part at a fixed period of 5ms, and the energy value detected by the detector is processed using the second-order Butterworth low-pass filter algorithm. The processed data is used as the background signal of the working environment of the seeker at the current moment. ; Step (3) Before the seeker starts searching for the target, it does not respond to the trigger signal. At this time, the initial threshold The background signal detected in step (2) Add together as the detection threshold at the current moment ,Right now ; Step (4) After the seeker intercepts the target, the target signal energy increases rapidly as the distance between the missile and the target decreases. At this time, the seeker dynamically adjusts the signal strength through the built-in programmable gain amplifier. G , the detection threshold calculated in step (3) Make another correction to get the detection threshold at the current moment after correction .

2. A dynamic threshold adjustment method for a laser semi-active guidance head according to claim 1, characterized in that The circuit part can convert optical signals into electrical signals and perform signal conditioning, complete signal acquisition, resolution and dynamic threshold adjustment, and output the resolved target information to the host computer.

3. A dynamic threshold adjustment method for a laser semi-active guidance head according to claim 2, characterized in that The circuit part specifically includes: (1) Laser four-quadrant detector assembly SPD046, completes the photoelectric conversion of laser signals and outputs four-quadrant voltage; (2) High-gain variable gain amplifier AD8336, which amplifies and conditions the weak voltage signal output by the laser four-quadrant detector; (3) Wave gate selection circuit, to realize the wave gate control of the circuit simulation channel; (4) Four-way summing circuit AD8062ARM, which sums the four-quadrant voltages for back-end threshold comparison; (5) Sample and hold circuit SMP04ES, which holds the four-quadrant voltage for back-end AD acquisition; (6) The time identification circuit TLV3051 compares the summed voltage signal with a preset threshold value, and after comparison, uses a D flip-flop to convert it into a digital signal to obtain a trigger signal for time identification; (7) High-speed AD acquisition circuit AD7606B, to collect the four-quadrant voltage signal after holding; (8) Digital-to-analog conversion circuit AD5722, which realizes the digital-to-analog conversion of the variable gain amplifier gain and the signal comparison threshold; (9) Processor circuit DSP28377D, realizing data processing, communication and status control; (10) The power supply circuit realizes the conversion of external power supply to internal voltage, and converts the 28V input power supply into the power output required for the operation of various subsystems and devices.

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