A target detection method and system based on differential positioning and inertial navigation

Abstract

The application provides a target detection method and system based on differential positioning and inertial navigation, and belongs to the technical field of target detection based on differential positioning and inertial navigation; the technical problem to be solved is to provide an improved target detection method and detection system hardware structure based on differential positioning and inertial navigation; the technical solution for solving the technical problem is that a terminal display control system is arranged in a control room, a signal processor of a radar is arranged on a detection site, the terminal display control system is connected to the signal processor through a communication interface to preset radar working parameters, control instructions are sent to a servo driving system and state monitoring is performed, the servo driving system is arranged to realize antenna azimuth rotation control and provide azimuth coding for signal processing, and the signal processor is arranged to generate CPI and PRF time sequence signals required by radar working and complete digital detection of echoes; the application is applied to ground or air target detection.

Description

TECHNICAL FIELD

[0001] The application provides a target detection method and system based on differential positioning and inertial navigation, and belongs to the technical field of target detection based on differential positioning and inertial navigation. BACKGROUND

[0002] Low, slow and small targets refer to small flight targets flying at low or ultra-low altitudes, such as unmanned aerial vehicles and other aircraft. Due to the lack of effective technical means for monitoring, the supervision of unmanned aerial vehicles is significantly lagging behind, and the monitoring and countermeasures for unmanned aerial vehicles and other aircraft are insufficient. Although some unmanned aerial vehicle enterprises have set up no-fly zones for unmanned aerial vehicle flights in their products, it is limited to some areas. With the increasing popularity of unmanned aerial vehicles in recent years, people purchase parts to modify the existing functions of unmanned aerial vehicles for various purposes when traveling, and fly unmanned aerial vehicles in various no-fly zones without flight and safety training. In recent times, there have been several safety accidents. However, the current control and management of unmanned aerial vehicles is difficult to cover all aspects, especially in complex and harsh environments, making target detection more difficult. In addition to addressing the problem from the source, improvements are needed in the detection system and method for unmanned aerial vehicle targets. SUMMARY

[0003] The application aims to overcome the deficiencies in the prior art and solve the technical problem of improving the hardware structure of the target detection method and system based on differential positioning and inertial navigation.

[0004] To solve the above technical problems, the application adopts the technical scheme of a target detection method based on differential positioning and inertial navigation, comprising the following detection steps:

[0005] Step 1: A terminal display control system is set up in the control room, and a radar signal processor is set up in the detection site. The terminal display control system is connected to the signal processor through a communication interface to realize the presetting of radar operating parameters, send control instructions to the servo drive system and perform state monitoring. The servo drive system is set up to realize antenna azimuth rotation control and provide azimuth encoding for signal processing.

[0006] The signal processor is set up to generate CPI and PRF timing signals required for radar operation and complete digital detection of echoes.

[0007] A frequency synthesis module is set up to generate a small RF signal required for transmission and a local oscillator signal for reception.

[0008] A solid-state transceiver module is set up to amplify the transmission signal power and mix the received target echo signal.

[0009] A secondary power supply is set up to perform power conversion and provide working power for the signal processor and the transceiver subsystem.

[0010] Step two: control signal processor power, by terminal display control system sends radar state query instruction, for viewing the working status of all devices:

[0011] When the system detects an abnormality, the system will automatically locate the fault link and display on the terminal display control system to remind the operator to perform maintenance intervention operation;

[0012] When the system detects normal, the system will automatically enter the default working mode of radar to investigate the area of interest;

[0013] Step three: after entering the working mode, the terminal display control system sends radar working parameters to the signal processor, the signal processor generates the specified working time sequence command according to the requirements and sends it to the transceiver subsystem, the frequency synthesis module in the transceiver subsystem generates the radio frequency excitation signal according to the time sequence signal and working frequency control information provided by the signal processor, and sends it to the solid-state transceiver module for power amplification, and then sends the amplified signal to the planar array antenna, and radiates radar detection signal to the outside world through the planar array antenna;

[0014] Step four: the radar detection signal is sent to the target to produce a return signal, the return signal is received by the planar array antenna to form three signals of azimuth, azimuth difference and elevation difference, which are sent to the signal processor after passing through the built-in circulator, limiter, low noise amplifier and mixer in the solid-state transceiver module;

[0015] The signal processor performs A / D conversion, digital down conversion processing on the three intermediate frequency signals, then performs pulse compression, MTD, constant false alarm, clutter map processing, and threshold decision, analyzes and processes the signals that pass the threshold in terms of distance, azimuth, amplitude and time to form target information, and then the signal processor sends the target information to the terminal display control system for display.

[0016] The specific steps for clutter map processing of the signal in step four are:

[0017] Step 4.1: considering the influence of ground clutter on the signal, the radar reflection cross section calculation formula of the ground clutter is:

[0018] σc=Rθaz(Cτ / 2)(σ0 / Lp);

[0019] Where: R is the distance, θaz is the 3dB width of the azimuth beam, which is 5.2°, τ is the compressed pulse width, c is the speed of light, σ0 is the ground reflection coefficient, X band is-20dB, Lp=1.33dB is the beam shape loss;

[0020] The radar cross section of the ground clutter at different distances is calculated based on the above formula, and the signal is processed;

[0021] Step 4.2: Considering the influence of weather clutter on the signal, the radar cross section of the weather clutter is calculated according to the formula:

[0022] σc=RθazRθel(Cτ / 2)η;

[0023] Wherein: θaz is the 3dB width of the azimuth beam, 5.2°, θel is the 3dB width of the elevation beam, 8°, η is the reflection efficiency, R is the distance, τ is the pulse width, and c is the speed of light;

[0024] The calculation formula of the reflection efficiency in the above formula is:

[0025] η=6×10 -14 ×r 1.6 ×λ -4 ;

[0026] Wherein: r is the rainfall, and λ is the radar wavelength, and the radar wavelength λ is 0.028m;

[0027] The radar cross section of the weather clutter at different distances is calculated based on the above formula, and the signal is processed;

[0028] Step 4.3: Based on the ground clutter and weather clutter data improvement factor, the calculation formula of the improvement factor is:

[0029]

[0030] Wherein: And σ T Respectively, the radar reflection area intensity of clutter and the radar reflection area intensity of target, and Do is the detection factor;

[0031] It is defined that when the calculation result of the improvement factor I is not less than 52dB, the use requirement can be met.

[0032] A target detection system based on differential positioning and inertial navigation, comprising a terminal display control system arranged in a control room, and a signal processor arranged in a detection site, the signal processor is connected with a servo drive system and a transceiver system through wires, the transceiver system is internally provided with a frequency synthesis module and a solid-state transceiver module, the frequency synthesis module is connected with the solid-state transceiver module through wires, the frequency synthesis module is connected with the signal processor through wires, and the solid-state transceiver module is connected with a planar array antenna through wires;

[0033] The power input ends of the signal processor and the transceiver system are connected with a secondary power module;

[0034] The signal processing machine is also connected to a servo drive system by a wire.

[0035] The present application has the following advantages: the present application provides a radar detection system for monitoring and locking unmanned aerial vehicles, the signal processing device of the radar is remotely controlled by the terminal control system, the radar antenna is sent a detection instruction, the radar antenna transmits a detection signal to the target, the received echo signal is analyzed and processed, the echo signal is corrected while excluding interference factors such as ground objects and weather, and the accurate distance, direction, amplitude, time and other information of the target are obtained; the target automatic detection system provided by the present application meets the technical indicators, the risk is controllable, and the system has good realizability; the system is not affected by bad weather or geology when detecting the target, and has data processing capability in a complex electromagnetic environment; the detection system has the advantages of low risk, low cost and high reliability, and can improve the environmental adaptability, electromagnetic compatibility, reliability and self-maintenance capability of the target detection system. BRIEF DESCRIPTION OF DRAWINGS

[0036] The present application will be further described below with reference to the accompanying drawings:

[0037] Figure 1 The present application is a schematic diagram of the hardware structure of the target detection system;

[0038] Figure 2 The present application is a schematic diagram of the circuit structure of the target detection system;

[0039] Figure 3 The present application is a schematic diagram of the radar scanning direction;

[0040] Figure 4 The present application is a schematic diagram of the radar power coverage;

[0041] Figure 5 The present application is a schematic diagram of the relationship between the ground clutter and weather clutter reflection area and distance;

[0042] Figure 6 The present application is a schematic diagram of the network structure of the monitoring radar. DETAILED DESCRIPTION

[0043] The application combines GNSS differential positioning with inertial navigation technology, and provides a method for detecting a target in a complex environment based on a GNSS and inertial navigation combined system, which mainly detects a low, slow and small target through a radar, locks the target through an optical video system, and counteracts after determining the specific three-dimensional coordinates of the target; the target detection system mainly comprises a pulse Doppler multi-coordinate radar for detecting an aerial target at a long distance, and realizes that a flying object can be detected at a distance (6 kilometers) or more, and the flying object is identified at a medium and short distance (1.5 kilometers and 3 kilometers) based on an all-around spectrum detection method and a pilot detection and locking method; the target detection system adopts a long-range photoelectric camera tracking and identification method to lock the target at a close distance (within 1.5 kilometers), and the whole process analyzes and processes the detection data based on a terminal display and control system provided by an upper computer.

[0044] As shown in Figure 1 , the target detection system provided by the application is a portable and multipurpose short-range monitoring radar, which can be used for detecting ground personnel, vehicles or unmanned aerial vehicles; the monitoring radar mainly comprises a support part, an antenna part and an interface device; the support part can be supported by a tripod or fixed on the ground according to different installation forms; the antenna part comprises a radome, a planar array antenna, a frequency synthesis module, an all-solid-state transceiver module, a signal processor, a secondary power supply and a servo driver; and the interface device comprises a power supply unit and a terminal display and control unit.

[0045] The monitoring radar used in the application is a single-pulse three-coordinate radar adopting azimuth / elevation mechanical scanning, single-pencil beam transmission and azimuth reception; the radar is powered by alternating current 220V 50Hz; and the antenna comprises a secondary power supply for providing power conversion.

[0046] As shown in Figure 2 , the terminal display and control system of the application realizes presetting of radar working parameters, command control of a servo drive and state monitoring through a communication interface with a signal processor; the signal processor is used for generating time sequence signals such as CPI and PRF required for radar work, and completing digital detection of echoes; the frequency synthesis module is used for generating a radio frequency small signal required for transmission and a local oscillation signal for reception; the solid-state transceiver module realizes power amplification of a transmission signal and mixed frequency reception of a target echo signal; the servo system is used for realizing azimuth rotation control of the antenna and providing azimuth encoding signals for signal processing; and the secondary power supply is used for power conversion, and provides required working power for signal processing and a transceiver subsystem.

[0047] After the radar is powered on, the terminal display control system first sends a state query instruction of radar operation, which is used to check the working state of all devices. When there is an abnormality in the device, the system will automatically locate the possible fault link and display it on the relevant interface of the terminal to remind the operator to perform maintenance intervention and the like. When the system is normal, the radar can automatically enter the default working mode to realize the investigation of the concerned area.

[0048] When entering the normal working state, the terminal display control system first sends the radar working parameters to the signal processor. The signal processor generates the specified working time sequence and the like according to the requirements and sends them to the transceiver subsystem. The frequency synthesis module in the transceiver subsystem generates the radio frequency excitation signal according to the time sequence signal and the working frequency control information provided by the signal processor, and sends it to the solid-state transceiver module for power amplification. The amplified signal is sent to the planar array antenna end, and is radiated to the outside world through the antenna. The target echo signal is received by the planar array antenna to form three signals of azimuth and, azimuth difference and elevation difference. The three signals are sent to the signal processor through the circulator, limiter, low noise amplifier and mixer of the solid-state transceiver module. The signal processor performs A / D conversion and digital down conversion processing on the three intermediate frequency signals, and then performs pulse compression, MTD, constant false alarm, clutter map and the like processing. The threshold decision is made, and the distance, azimuth, amplitude and time of the signal over the threshold are processed to form target information. The information is reported to the radar terminal display computer, and is displayed on the terminal.

[0049] The present application selects the radar frequency band:

[0050] When selecting the radar working frequency band, the main factors such as the requirement of radar detection capability, engineering realizability and the frequency band of radar equipment distribution should be considered. In order to ensure the detection power of the radar, the working frequency band is selected as the X band. At this frequency, the detection power, measurement accuracy and antenna size of the radar can be well balanced. In terms of engineering realizability, the development cycle and cost are analyzed to determine the possible frequency range. Considering the above factors, the radar working frequency band selected by the present application is in the X band, and the frequency is 10.38-10.48 GHz.

[0051] The selection of signal transmission form:

[0052] The most common method is to improve the average power of the transmitter by using a signal with large time-bandwidth product and to ensure the range resolution by pulse compression, therefore, the application adopts a large time-bandwidth frequency pulse compression system, and the frequency pulse adopts a linear frequency modulation form; in order to consider the minimum detectable distance and radar power, long and short width signal forms are selected, wherein the long pulse signal adopts a linear frequency modulation form to realize the search of the middle and far area target, and the short pulse signal adopts a simple pulse form to complete the search of the near area target; the long pulse selected by the application has a design detection range of 4km-12km, and the short pulse has a design detection range of 75m-4.5km.

[0053] The selection of the radar scanning direction is as follows:

[0054] In order to realize the requirement of 360° full coverage of the detection direction, the main systems that can be selected are a direction mechanical scanning system and a direction electrical scanning system, and the direction scanning is realized under the control of a direction servo driving system to complete the detection function of the concerned area; the radar of the application selects a direction mechanical scanning scheme, and a direction scanning schematic view is as shown in the figure. Figure 3 The radar provided by the application adopts a direction sector scanning mode, and can realize the observation of the area between-178° and 178°, since the antenna direction beam width is about 5°, therefore, the requirement of 360° full coverage of the direction can be met according to the mode, and the current ring part is saved, the system complexity and design cost are reduced, and the reliability is improved; the above direction observation range can be set according to the requirement, and the staring function of a certain angle can also be realized, the detection ability of a specific target is improved through the redistribution of the space energy.

[0055] The calculation of the radar detection power is as follows:

[0056] The calculation formula of the radar detection distance is as follows:

[0057]

[0058] The meanings of the parameters in the formula are shown in Table 1.

[0059]

[0060] Table 1: Simulation parameter table for power derivation

[0061] The selection of the working mode is as follows:

[0062] The radar provided by the application is provided with two working modes: normal search and staring mode, and the main working parameters are shown in Table 2.

[0063] Operating mode Rotational speed (rpm) PRF period (us) Pulse width (us) Long / short code Range (Km) Normal search 1 130 25 / 0.5 15 Gaze 0 130 25 / 0.5 15

[0064] Table 2: Comparison of radar working mode parameters

[0065] In the search mode, the search mode is the main working mode of the radar, and is used to complete the search detection of the target. In this mode, the angle between the normal direction of the antenna and the horizontal direction is set to 1.8°, and the rotation speed of the antenna is set to 1 revolution per minute.

[0066] The transmitting beam of the control plane array antenna is a single pencil beam, the elevation beam width is 8°, and the azimuth beam width is 5.2°; the receiving adopts a sum-difference monopulse form. When the rotation speed is 1 revolution per minute, the main design parameters are as follows:

[0067] Distance range: 15 km;

[0068] Antenna rotation speed: 1 rpm (6° / s);

[0069] Azimuth coverage range: -178° to +178°;

[0070] Elevation coverage range: -5° to +20°;

[0071] Elevation beam: pencil beam, width 8°;

[0072] Maximum effective distance:

[0073] Walking personnel (V>0.5m / s): 9km (RCS=0.5m2, Pd=80%)

[0074] Moving vehicle (V>2m / s): 15km (RCS=30m2, Pd=80%)

[0075] Unmanned aerial vehicle (V>1m / s): 4km (RCS=0.05m2, Pd=80%)

[0076] Minimum effective distance: ≤75m:

[0077] Pulse repetition period: 130μs;

[0078] Pulse width: 25μs (long pulse), 0.5μs (short pulse);

[0079] MTD points: 4096.

[0080] In the search mode, the radar transmits pulse width: long pulse 25μs, short pulse 0.5μs, wherein the long pulse signal is a linear frequency modulation signal, which is used for medium and long range target detection, and the short pulse signal is a simple pulse signal, which is used for near range target detection.

[0081] As shown in Figure 4 According to the radar power coverage diagram, the long pulse power coverage range is 3.7-10km; the short pulse power coverage range is 75m-4.2Km, and the long and short pulses can well realize distance connection.

[0082] The radar azimuth in the gaze mode does not scan, but stays at a fixed azimuth angle, and the 3D information display function of the specified azimuth, full distance and full speed channel can be completed by increasing the dwell time, the target detection and identification are completed by manual interpretation, and the monitoring of the key concerned area is realized.

[0083] Further, the anti-passive interference characteristics need to be analyzed while detecting the air target, and the radar needs to consider the following when detecting the target:

[0084] 1. Consider the ground clutter:

[0085] The ground clutter is a surface clutter, and its intensity is related to the clutter area irradiated by the radar antenna beam and the backscattering coefficient size of the clutter, and the radar reflection cross section area of the ground clutter can be expressed as:

[0086] σc=Rθaz(Cτ / 2)(σ0 / Lp);

[0087] In the formula, R is the distance, 0az is the 3dB width of the azimuth beam, which is 5.2°, τ is the compressed pulse width (the estimated value is 2.6us considering windowing), c is the speed of light, σ0 is the ground reflection coefficient, which is-20dB in X band, and Lp=1.33dB is the beam shape loss.

[0088] Therefore, the ground clutter intensities of different distances are as shown in the following table:

[0089] Distance (km) 1 3 5 10 dBm 2 )]]> 24.5 29.1 31.4 34.5

[0090] Table 3: Corresponding table of ground clutter intensity and distance

[0091] 2. Consider the weather clutter:

[0092] The weather clutter is a volume clutter, and its radar reflection cross section area can be expressed as:

[0093] σc=RθazRθel(Cτ / 2)η;

[0094] In the formula, 0az is the 3dB width of the azimuth beam, which is 5.2°, θel is the 3dB width of the elevation beam, which is 8°, η is the reflection efficiency, R is the distance, τ is the pulse width, and c is the speed of light.

[0095] The calculation formula considering the reflection efficiency is:

[0096] η=6×10 -14 ×r 1.6 ×λ -4 ;

[0097] Wherein r is the rainfall (mm / hour), and λ is the wavelength (m).

[0098] The radar wavelength is 0.028m, and the relationship between η and the rainfall r is shown in the following table:

[0099] Rain rate r (mm / h) 4 10 30 100 Reflection efficiency η (m2 / m3) 8.97×10-7 3.89×10-6 2.25×10-5 1.55×10-4

[0100] Table 4 Correspondence table of meteorological clutter reflection efficiency and rainfall

[0101] The embodiment calculates the clutter intensity when the rainfall is 10mm / h, and the value is shown in the following table:

[0102] Distance (km) 1 3 5 10 Rain clutter cross section area (dBm2) 12.4 22.6 27.1 33.3

[0103] Table 5 Correspondence table of meteorological clutter intensity and distance

[0104] The corresponding ground clutter and meteorological clutter intensity is calculated at 10km, and the calculation structure is shown in Figure 5

[0105] 3. Consideration of improvement factor:

[0106] The required improvement factor is shown in the following formula, and the calculation formula is:

[0107]

[0108] In the formula: and σ T are the clutter radar reflection surface intensity and the target radar reflection surface intensity respectively, Do is the detection factor, and for the RCS of 0.5m2 target, for 10km ground clutter, I≥50.1dB; for 10km meteorological clutter (rainfall is 10mm / h), I≥48.9dB;

[0109] The design index of the embodiment for the improvement factor is 52dB, which can meet the use requirements.

[0110] The calculation formula of the total improvement factor limit I of the system is:

[0111]

[0112] In the formula, the improvement factor limit is:

[0113] Clutter internal fluctuation: I1=64dB;

[0114] Antenna scanning modulation: I2=66dB;

[0115] Local oscillator frequency stability: I3=70dB;

[0116] Transmit signal amplitude stability: I4=70dB;

[0117] Transmit signal pulse width jitter: I5=70dB; ​

[0118] Receiver linear dynamic range: I6 = 60 dB;

[0119] A / D quantization: I6 = 64 dB.

[0120] Further, the present application can also use radar networking for monitoring, the radar used by the present application belongs to ground monitoring radar, since the action distance is only 10 Km, therefore in order to meet the monitoring of large range area coverage, according to the user's demand, multiple radars can be considered to be configured in network, each radar station terminal equipment is interconnected with the superior intelligence monitoring network, the state control (working frequency, etc.) of each radar is realized by the superior intelligence network, each radar works independently, and the information in the detection area of each radar is reported to the superior intelligence monitoring network by the terminal, the schematic diagram of the radar network function is shown in Figure 6 .

[0121] Finally, the time distribution of radar deployment and withdrawal needs to be considered: the mobile monitoring radar is composed of antenna part, support part and related communication and power supply cable, first of all, a flat and hard site is selected, then the radar support part is erected, fixed firmly, then the antenna part is reliably installed on the support part, and finally the communication and power supply cable is connected. Since the system is simple in composition and the parts are regular, the erection time can meet the 3 min index requirement; the withdrawal is the reverse process of erection, first of all, the radar is shut down, then the power supply and communication cable is disconnected, and finally the antenna and support parts are removed. At this time, the radar completes the withdrawal work and can meet the transfer needs.

[0122] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A target detection method based on differential positioning and inertial navigation, characterized in that: The testing steps include the following: Step 1: Set up a terminal display and control system in the control room and a radar signal processor at the testing site. The terminal display and control system interfaces with the signal processor to preset the radar operating parameters, send control commands to the servo drive system and monitor its status. The servo drive system is set up to control the antenna azimuth rotation and provide azimuth coding for signal processing. The signal processor is set up to generate the CPI and PRF timing signals required for radar operation and to complete the digital detection of the echo; a frequency synthesis module is set up to generate the radio frequency small signals required for transmission and to receive the local oscillator signal. A solid-state transceiver module is installed to amplify the transmitted signal power and to mix and receive the target echo signal. A secondary power supply is set up to perform power conversion and provide working power for the signal processor and transceiver subsystem; Step Two: Power on the control signal processor, and the terminal display and control system will issue a status query command for the radar to check the working status of all devices. When the system detects an anomaly, it will automatically locate the faulty component and display it on the terminal display and control system, reminding the operator to perform maintenance intervention. When the system detects that everything is normal, the system will automatically enter the radar's default working mode and conduct reconnaissance on the area of ​​interest. Step 3: After entering the working mode, the terminal display and control system sends radar working parameters to the signal processor. The signal processor generates the specified working timing command as required and sends it to the transceiver subsystem. The frequency synthesis module in the transceiver subsystem generates radio frequency excitation signal according to the timing signal and working frequency control information provided by the signal processor and sends it to the solid-state transceiver module for power amplification. Then, the amplified signal is sent to the planar array antenna, which radiates the radar detection signal to the outside world. Step 4: After the radar detection signal is sent to the target, an echo signal is generated. The echo signal is received by the planar array antenna to form three signals: azimuth sum, azimuth difference, and elevation difference. The three signals are sent to the signal processor after passing through the circulator, limiter, low noise amplifier, mixer, and intermediate frequency amplifier built into the solid-state transceiver module. The signal processor performs A / D conversion and digital down-conversion on the three intermediate frequency signals, then performs pulse compression, MTD, constant false alarm rate, and clutter graph processing, and performs threshold decision. For signals that exceed the threshold, the distance, azimuth, amplitude, and time are analyzed and processed to finally form target information. The signal processor then sends the target information to the terminal display and control system for display. The specific steps for clutter diagram processing of the signal are as follows: Step 4.1: Considering the impact of ground clutter on the signal, the formula for calculating the radar cross-section of the ground clutter is: σc=Rθaz(Cτ / 2)(σ0 / Lp); In the formula: R is the distance, θaz is the azimuth beamwidth in 3dB (taken as 5.2°), τ is the compressed pulse width, C is the speed of light, σ0 is the ground reflection coefficient (taken as -20dB for X-band), and Lp = 1.33dB is the beam shape loss. The radar cross-section data of ground clutter at different distances are obtained based on the above formula and the signal is processed. Step 4.2: Considering the impact of meteorological clutter on the signal, the formula for calculating the radar cross-section of the meteorological clutter is: σc=RθazRθel(Cτ / 2)η; In the formula: θaz is the azimuth beamwidth of 3dB, which is taken as 5.2°, θel is the elevation beamwidth of 3dB, which is taken as 8°, η is the reflection efficiency, R is the distance, τ is the pulse width, and c is the speed of light; The formula for calculating reflection efficiency in the above equation is: n=6×10 -14 ×r 1.6 ×λ -4 , In the formula: r is the rainfall, λ is the radar wavelength, and the radar wavelength λ is taken as 0.028m; The radar cross-section data of meteorological clutter at different distances are obtained based on the above formula and the signal is processed. Step 4.3: Improvement factor based on ground clutter and meteorological clutter data. The formula for calculating the improvement factor is as follows: In the formula: and σ T These are the intensity of the clutter radar reflector and the intensity of the target radar reflector, respectively, with Do being the detection factor; The definition is that the usage requirements can be met when the calculated result of the improvement factor I is not less than 52dB.

2. A target detection system based on differential positioning and inertial navigation, used to implement the target detection method based on differential positioning and inertial navigation as described in claim 1, characterized in that: It includes a terminal display and control system installed in the control room and a signal processor installed at the testing site. The signal processor is connected to the servo drive system and the transceiver subsystem via wires. The transceiver subsystem is equipped with a frequency synthesis module and a solid-state transceiver module. The frequency synthesis module is connected to the solid-state transceiver module via wires. The frequency synthesis module is connected to the signal processor via wires. The solid-state transceiver module is connected to the planar array antenna via wires. The power input terminals of the signal processor and the transceiver subsystem are both connected to the secondary power supply module. The signal processor is also connected to the servo drive system via wires.

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