1. A method for detecting accumulation of a weak target of a high-frequency ground wave radar is characterized by comprising the following steps:

s1, acquiring an echo signal of the high-frequency ground wave radar, and performing pulse compression to obtain a high-frequency ground wave radar pulse pressure signal;

s2, setting search parameters of three-dimensional combined search of radial distance, radial speed and real speed according to the parameters of the high-frequency ground wave radar;

step S3, carrying out three-dimensional combined search on the radial distance, the radial speed and the real speed of the high-frequency ground wave radar pulse pressure signal;

step S4, extracting target track signals of the high-frequency ground wave radar according to the search parameters;

s5, constructing a phase compensation function along the slow time dimension of the high-frequency ground wave radar;

step S6, compensating the phase fluctuation of the extracted target track signal among pulses along the high-frequency ground wave radar pulse sequence, and adding the echo envelopes of the compensated target track signal in phase to complete phase-coherent accumulation;

step S7, setting detection parameters, carrying out three-dimensional constant false alarm rate detection based on the result of coherent accumulation, judging whether a target is detected, and executing the next step if the target is detected;

and step S8, performing parameter estimation on the detected target, dividing target attributes according to the radial speed and the real speed of the target, and outputting a target detection result and the target attributes.

2. The method for detecting accumulation of weak targets in high-frequency ground wave radar according to claim 1, wherein the step S7 includes:

step S7-1, initializing detection parameters and setting false alarm probability P_faRespectively setting the number of reference units and protection units in three detection domains, namely a radial distance domain, a radial speed domain and a real speed domain according to the number of units occupied by a target peak value which finishes coherent accumulation in the detection domains;

step S7-2, respectively in three detection domains of radial distance domain, radial velocity domain and real velocity domain, according to the number of reference units and false alarm probability P_faCalculating a corresponding CFAR threshold factor, wherein the expression is as follows:

where T represents the corresponding CFAR threshold factor in a detection domain, N_cRepresenting the number of reference cells in the detection domain;

step S7-3, respectively in three detection domains of a radial distance domain, a radial velocity domain and a real velocity domain, calculating a noise floor according to the detection units and a plurality of reference units, wherein the noise floor is equal to the sum of coherent accumulation echo amplitudes corresponding to each reference unit in one detection domain and then divided by the number of the reference units;

step S7-4, calculating the detection threshold corresponding to the detection unit in three detection domains of a radial distance domain, a radial speed domain and a real speed domain, wherein the expression is as follows:

S＝T*N

wherein, S is a corresponding detection threshold in a detection domain, T is a corresponding CFAR threshold factor in the detection domain, and N is a corresponding noise floor in the detection domain;

step S7-5, judging whether coherent accumulation echo amplitudes of the detection unit in three detection domains of a radial velocity domain, a radial distance domain and a real velocity domain all exceed corresponding detection thresholds, if so, judging the detection unit to be a peak value unit, and if not, judging the detection unit to be a target;

and S7-6, judging whether all the detection units are traversed or not, if so, executing the next step, otherwise, stepping the detection units, and returning to the step S7-2.

3. The method for detecting accumulation of weak targets in high-frequency ground wave radar according to claim 2, wherein in step S8, when performing parameter estimation on the detected targets, the estimated values of the parameters of the peak targets in each detection domain are obtained by a three-point quadratic interpolation method;

when the peak value corresponding to the target appears in the J-th unit, three-point secondary interpolation is carried out by utilizing the coherent accumulation amplitude of the J-th unit where the peak value is located, the coherent accumulation amplitude of the J-1-th unit adjacent to the peak value and the coherent accumulation amplitude of the J + 1-th unit adjacent to the peak value, the parameter value corresponding to the unit where the maximum value is located is estimated to serve as the estimated value of the peak value target parameter in a detection domain, and the expression is as follows:

wherein x is_JThe parameter value of the J-th unit is shown, and f (J) shows the coherent accumulation amplitude of the J-th unit.

4. The method for detecting accumulation of weak targets in high-frequency ground wave radar according to claim 1, wherein in step S1, the expression of the pulse pressure signal of the high-frequency ground wave radar is obtained as follows:

wherein, t_m＝mT_r(M-0, 1.., M-1) represents a slow time, M is a high-frequency ground wave radar pulse accumulation number, and T is_rIs the pulse period of high-frequency ground wave radar, tau represents fast time, K is the target number, A_i1For the ith target high-frequency ground wave radar pulse pressure signal amplitude, B represents high frequencyThe bandwidth of a ground wave radar transmitting signal, c is the speed of light, and lambda is c/f_cRepresenting the radar wavelength, f, of high-frequency ground waves_cFor high frequency ground wave radar carrier frequency, r_i(t_m) Is the radial distance equation for the ith target.

5. The method for detecting the accumulation of the weak target of the high-frequency ground wave radar as claimed in claim 4, wherein in the step S2, the setting of the search parameters of the three-dimensional joint search of the radial distance, the radial velocity and the real velocity comprises:

step S2-1, according to the power range 0-R of the high-frequency ground wave radar_maxSetting a radial distance search range r_min～r_max：

r_min＝0,r_max＝R_max

Unambiguous velocity measurement range from high-frequency ground wave radarSetting radial velocity search range

Detecting a target type maximum velocity V from a high frequency ground wave radar_maxSetting a true velocity search range v_min～v_max：

v_min＝0,v_max＝V_max

Step S2-2, setting a radial distance search interval according to the size of the high-frequency ground wave radar range gate:

wherein f is_sSampling for high frequency ground wave radarRate, c is the speed of light;

setting a radial speed search interval according to the Doppler resolution of the high-frequency ground wave radar:

setting a speed search interval according to the Doppler resolution of the high-frequency ground wave radar:

step S2-3, determining the search numbers of the distance, radial velocity and true velocity of the target, respectively expressed as:

wherein round (·) represents the rounding operation, and the rounding method is rounding;

step S2-4, obtaining the discretized search distance, the search radial velocity and the search real velocity, which are respectively expressed as:

r_n＝nΔr,n＝0,1,...,N_r-1

v_q＝qΔv,q＝0,1,...,N_v-1

completing search parametersAnd (4) setting.

6. The method for detecting accumulation of weak targets in high-frequency ground wave radar according to claim 5, wherein in step S3, performing three-dimensional joint search on radial distance, radial velocity and true velocity of the high-frequency ground wave radar pulse pressure signal includes:

the three-dimensional joint search definition formula of the radial distance, the radial speed and the real speed is obtained as follows:

where r represents the radial distance unit of the search,represents the radial velocity unit of the search, v represents the true velocity unit of the search,indicates a search parameter ofThe coherent accumulation amplitude value;

substituting high-frequency ground wave radar pulse pressure signal s_c(t_mτ) expression, there is:

wherein the content of the first and second substances,t representing search_mThe radial distance value at the moment.

7. The method for detecting the accumulation of the weak targets of the high-frequency ground wave radar according to claim 6, wherein in step S4, the extracting the target track signals of the high-frequency ground wave radar according to the search parameters includes:

searching for parametersIn the case, the number of cross-distance units of the echo envelope of each pulse period is calculated, and the expression is as follows:

aligning each pulse period echo envelope to a distance unit where an initial radial distance is located, and finishing target track signal extraction of the high-frequency ground wave radar, wherein the expression is as follows:

s(t_m)＝s_c(t_m,k(t_m))

wherein, s (t)_m) Represents the extracted t_mTarget track signal of time of day.

8. The method for detecting accumulation of weak targets in high-frequency ground wave radar according to claim 7,

in step S5, a phase compensation function is constructed along the slow time dimension of the high-frequency ground wave radar, and the expression is:

in step S6, the echo envelopes of the compensated target track signals are added in phase to complete coherent accumulation, where the expression is:

wherein the content of the first and second substances,indicates a search parameter ofThe coherent accumulated amplitude values.

9. A computing device comprising a memory having stored therein a computer program and a processor that, when executing the computer program, implements a high frequency ground wave radar weak target accumulation detection method as claimed in any one of claims 1 to 8.

10. A computer-readable storage medium having stored thereon a computer program which, when executed in a computer, causes the computer to execute the high frequency ground wave radar weak target accumulation detection method of any one of claims 1 to 8.

Background

High Frequency Surface Wave Radar (High Frequency Surface Wave Radar) uses the diffraction effect of long electromagnetic waves on the earth Surface (including sea Surface) to make the electromagnetic waves propagate along the curved Surface of the earth. Based on the characteristic that the high-frequency band vertical polarization electromagnetic wave is low in propagation loss along the sea surface beyond the horizontal line, the high-frequency ground wave radar can detect over-the-horizon targets such as ships, airplanes and guided missiles, and the action distance is approximately 300-400 km, so that the high-frequency ground wave radar can fill blind areas which cannot be detected by the microwave line-of-sight radar and the sky wave beyond the-horizon radar. In addition, due to the characteristics of stable propagation, long working wavelength and the like, the high-frequency ground wave radar can effectively inhibit the stealth effect of the existing stealth technology, has the stealth resistance, and can find various targets from sea level to high altitude.

Although the high-frequency ground wave radar can continuously monitor the action range of the high-frequency ground wave radar all weather, sea ships and aerial moving targets in the action range can be found in time, the distance, the direction and the radial speed of the targets are measured, the track of the targets is processed, and the basic attribute characteristics of the targets are given; however, the object attributes cannot be correctly divided based only on the distance, orientation and radial velocity of the sea vessel and the airborne moving object. When the included angle between the target motion direction and the radar sight line direction is large, the real motion speed of the target is greatly different from the radial speed, for example, when a supersonic fighter flies in a direction close to the perpendicular direction of the radar sight line, the radial speed measured by the radar approaches to zero, which causes great difficulty in correctly dividing the target attribute, so that the real speed of the target needs to be obtained by technical means, and the current conventional radar resolving method cannot correctly obtain the real motion speed of the target monitored by the high-frequency ground wave radar.

In addition, with the continuous appearance of various high-speed and high-maneuverability targets, such as ultrahigh-sound-speed unmanned aerial vehicles, high-altitude high-sound-speed cruise missiles, ballistic missiles, high-space maneuvering aircrafts and the like, especially weak targets moving at high speed, echo signals received by high-frequency ground wave radars are extremely weak, and Signal-to-Noise Ratio (SNR) is extremely low.

Disclosure of Invention

The invention provides a weak target accumulation detection method, computing equipment and a computer readable storage medium for a high-frequency ground wave radar, which can perform range migration correction and Doppler phase compensation on a detection result of the high-frequency ground wave radar, can measure the real speed of a target, realize the increase of accumulation gain of radar echo, and inhibit noise and clutter interference, thereby effectively improving the detection performance of the high-speed weak target.

In a first aspect, an embodiment of the present invention provides a method for detecting accumulation of a weak target of a high-frequency ground wave radar, including:

s1, acquiring an echo signal of the high-frequency ground wave radar, and performing pulse compression to obtain a high-frequency ground wave radar pulse pressure signal;

s2, setting search parameters of three-dimensional combined search of radial distance, radial speed and real speed according to the parameters of the high-frequency ground wave radar;

step S3, carrying out three-dimensional combined search on the radial distance, the radial speed and the real speed of the high-frequency ground wave radar pulse pressure signal;

step S4, extracting target track signals of the high-frequency ground wave radar according to the search parameters;

s5, constructing a phase compensation function along the slow time dimension of the high-frequency ground wave radar;

step S6, compensating the phase fluctuation of the extracted target track signal among pulses along the high-frequency ground wave radar pulse sequence, and adding the echo envelopes of the compensated target track signal in phase to complete phase-coherent accumulation;

step S7, setting detection parameters, carrying out three-dimensional constant false alarm rate detection based on the result of coherent accumulation, judging whether a target is detected, and executing the next step if the target is detected;

and step S8, performing parameter estimation on the detected target, dividing target attributes according to the radial speed and the real speed of the target, and outputting a target detection result and the target attributes.

Preferably, the step S7 includes:

step S7-1, initializing detection parameters and setting false alarm probability P_faRespectively setting the number of reference units and protection units in three detection domains, namely a radial distance domain, a radial speed domain and a real speed domain according to the number of units occupied by a target peak value which finishes coherent accumulation in the detection domains;

step S7-2, respectively in three detection domains of a radial distance domain, a radial speed domain and a real speed domain,according to the number of reference units and the false alarm probability P_faCalculating a corresponding CFAR threshold factor, wherein the expression is as follows:

where T represents the corresponding CFAR threshold factor in a detection domain, N_cRepresenting the number of reference cells in the detection domain;

step S7-3, respectively in three detection domains of a radial distance domain, a radial velocity domain and a real velocity domain, calculating a noise floor according to the detection units and a plurality of reference units, wherein the noise floor is equal to the sum of coherent accumulation echo amplitudes corresponding to each reference unit in one detection domain and then divided by the number of the reference units;

step S7-4, calculating the detection threshold corresponding to the detection unit in three detection domains of a radial distance domain, a radial speed domain and a real speed domain, wherein the expression is as follows:

S＝T*N

wherein, S is a corresponding detection threshold in a detection domain, T is a corresponding CFAR threshold factor in the detection domain, and N is a corresponding noise floor in the detection domain;

step S7-5, judging whether coherent accumulation echo amplitudes of the detection unit in three detection domains of a radial velocity domain, a radial distance domain and a real velocity domain all exceed corresponding detection thresholds, if so, judging the detection unit to be a peak value unit, and if not, judging the detection unit to be a target;

and S7-6, judging whether all the detection units are traversed or not, if so, executing the next step, otherwise, stepping the detection units, and returning to the step S7-2.

Preferably, in step S8, when performing parameter estimation on the detected target, obtaining the estimated value of the peak target parameter in each detection domain by a three-point secondary interpolation method;

when the peak value corresponding to the target appears in the J-th unit, three-point secondary interpolation is carried out by utilizing the coherent accumulation amplitude of the J-th unit where the peak value is located, the coherent accumulation amplitude of the J-1-th unit adjacent to the peak value and the coherent accumulation amplitude of the J + 1-th unit adjacent to the peak value, the parameter value corresponding to the unit where the maximum value is located is estimated to serve as the estimated value of the peak value target parameter in a detection domain, and the expression is as follows:

wherein x is_JThe parameter value of the J-th unit is shown, and f (J) shows the coherent accumulation amplitude of the J-th unit.

Preferably, in step S1, the expression of the obtained high-frequency ground wave radar pulse pressure signal is:

wherein, t_m＝mT_r(M-0, 1.., M-1) represents a slow time, M is a high-frequency ground wave radar pulse accumulation number, and T is_rIs the pulse period of high-frequency ground wave radar, tau represents fast time, K is the target number, A_i1The pulse pressure signal amplitude of the ith target high-frequency ground wave radar is represented by B, the transmission signal bandwidth of the high-frequency ground wave radar is represented by c, the light speed is represented by c/f_cRepresenting the radar wavelength, f, of high-frequency ground waves_cFor high frequency ground wave radar carrier frequency, r_i(t_m) Is the radial distance equation for the ith target.

Preferably, in step S2, setting search parameters of a three-dimensional joint search of a radial distance, a radial velocity, and a true velocity includes:

step S2-1, according to the power range 0-R of the high-frequency ground wave radar_maxSetting a radial distance search range r_min～r_max：

r_min＝0,r_max＝R_max

Unambiguous velocity measurement range from high-frequency ground wave radarSetting radial velocity search range

Detecting a target type maximum velocity V from a high frequency ground wave radar_maxSetting a true velocity search range v_min～v_max：

v_min＝0,v_max＝V_max

Step S2-2, setting a radial distance search interval according to the size of the high-frequency ground wave radar range gate:

wherein f is_sThe sampling rate of the high-frequency ground wave radar is shown, and c is the speed of light;

setting a radial speed search interval according to the Doppler resolution of the high-frequency ground wave radar:

setting a speed search interval according to the Doppler resolution of the high-frequency ground wave radar:

step S2-3, determining the search numbers of the distance, radial velocity and true velocity of the target, respectively expressed as:

wherein round (·) represents the rounding operation, and the rounding method is rounding;

step S2-4, obtaining the discretized search distance, the search radial velocity and the search real velocity, which are respectively expressed as:

r_n＝nΔr,n＝0,1,…,N_r-1

v_q＝qΔv,q＝0,1,…,N_v-1

completing search parametersAnd (4) setting.

Preferably, in step S3, the three-dimensional joint search of the radial distance, the radial velocity, and the true velocity of the high-frequency ground wave radar pulse pressure signal includes:

the three-dimensional joint search definition formula of the radial distance, the radial speed and the real speed is obtained as follows:

where r represents the radial distance unit of the search,represents the radial velocity unit of the search, v represents the true velocity unit of the search,indicates a search parameter ofThe coherent accumulation amplitude value;

substituting high-frequency ground wave radar pulse pressure signal s_c(t_mτ) expression, there is:

wherein the content of the first and second substances,t representing search_mThe radial distance value at the moment.

Preferably, in step S4, the extracting the target track signal of the high-frequency ground wave radar according to the search parameter includes:

searching for parametersIn the case, the number of cross-distance units of the echo envelope of each pulse period is calculated, and the expression is as follows:

aligning each pulse period echo envelope to a distance unit where an initial radial distance is located, and finishing target track signal extraction of the high-frequency ground wave radar, wherein the expression is as follows:

s(t_m)＝s_c(t_m,k(t_m))

wherein, s (t)_m) Represents the extracted t_mTarget track signal of time of day.

Preferably, in step S5, a phase compensation function is constructed along the slow time dimension of the high-frequency ground wave radar, where the expression is:

in step S6, the echo envelopes of the compensated target track signals are added in phase to complete coherent accumulation, where the expression is:

wherein the content of the first and second substances,indicates a search parameter ofThe coherent accumulated amplitude values.

In a second aspect, an embodiment of the present invention further provides a computing device, including a memory and a processor, where the memory stores a computer program, and the processor, when executing the computer program, implements the method for detecting accumulation of weak targets in high-frequency ground wave radar according to any embodiment of the present specification.

In a third aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed in a computer, the computer program causes the computer to execute the method for detecting accumulation of weak targets in high-frequency ground wave radar according to any one of the embodiments in this specification.

The embodiment of the invention provides a weak target accumulation detection method, a calculation device and a computer readable storage medium for a high-frequency ground wave radar, aiming at the high-frequency ground wave radar, setting a search range and a search interval of three-dimensional combined search of a radial distance, a radial speed and a real speed according to parameters of a radar system, carrying out three-dimensional combined search of the radial distance, the radial speed and the real speed on a pulse pressure signal of the high-frequency ground wave radar, carrying out range migration correction and Doppler phase compensation based on a detection result of the high-frequency ground wave radar, reasonably utilizing a uniform motion model containing three-dimensional information of the radial speed, the radial distance and the real speed, realizing the high signal-to-noise ratio gain characteristic while finishing the target energy accumulation of the high-frequency ground wave radar, realizing the estimation of the real speed of the target so as to correctly divide target attributes of various targets, and simultaneously increasing the detection information of the real speed domain of the target, the detection probability of the high-speed weak target is further improved, and the detection performance of the high-frequency ground wave radar on the weak high-speed and high-maneuvering target is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flowchart of a method for detecting accumulation of weak targets in a high-frequency ground wave radar according to an embodiment of the present invention;

FIG. 2(a) is an RD diagram obtained by a weak target accumulation detection method of a high frequency ground wave radar according to an embodiment of the present invention; FIG. 2(b) is a RD diagram obtained by the MTD method;

FIG. 3 shows the detection results of the high-frequency ground wave radar weak target accumulation detection method and the MTD method in the radial velocity domain according to an embodiment of the present invention;

FIG. 4 shows the detection results of the high-frequency ground wave radar weak target accumulation detection method and the MTD method in the radial distance domain according to an embodiment of the present invention;

FIG. 5 shows the detection results of the high-frequency ground wave radar weak target accumulation detection method and the MTD method in the real velocity domain according to an embodiment of the present invention;

FIG. 6 shows a real velocity spectrum of a target plotted by a weak target accumulation detection method of a high-frequency ground wave radar according to an embodiment of the invention;

fig. 7 shows a comparison between the performance of a high-frequency ground wave radar weak target accumulation detection method provided by an embodiment of the present invention and that of an existing radial uniform motion coherent accumulation method.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.

As mentioned above, the high-speed characteristic of the target causes a Range Migration (RM) phenomenon in the conventional coherent accumulation process, and the high maneuvering characteristic of the target also causes a Doppler Frequency Migration (DFM) problem, so that the conventional coherent accumulation method of the high-Frequency ground wave radar faces a serious challenge in the detection of a weak target at high speed. The invention provides a weak target accumulation detection method of a high-frequency ground wave radar, which is based on a GRFT method, has a speed measurement function and is marked as a CVGRFT method.

Specific implementations of the above concepts are described below.

Referring to fig. 1, an embodiment of the present invention provides a method for detecting accumulation of weak targets in a high-frequency ground wave radar, including:

s1, acquiring an echo signal of the high-frequency ground wave radar, and performing pulse compression to obtain a high-frequency ground wave radar pulse pressure signal;

s2, setting search parameters of three-dimensional combined search of radial distance, radial speed and real speed according to the parameters of the high-frequency ground wave radar;

step S3, carrying out three-dimensional combined search on the radial distance, the radial speed and the real speed of the high-frequency ground wave radar pulse pressure signal;

step S4, extracting target track signals of the high-frequency ground wave radar according to the search parameters;

s5, constructing a phase compensation function along the slow time dimension of the high-frequency ground wave radar, and compensating the phase fluctuation of the extracted target track signal among pulses;

step S6, compensating the phase fluctuation of the extracted target track signal among pulses along the high-frequency ground wave radar pulse sequence, and adding the echo envelopes of the compensated target track signal in phase to complete phase-coherent accumulation;

step S7, setting detection parameters, carrying out three-dimensional constant false alarm rate detection based on the result of coherent accumulation, judging whether a target is detected, if the target is detected, executing the next step, namely, continuing to execute the step S8, otherwise, stepping the detection units until all the detection units are traversed;

and step S8, performing parameter estimation on the detected target, dividing target attributes according to the radial speed and the real speed of the target, and outputting a target detection result and the target attributes.

In the embodiment of the invention, after the coherent accumulation of the echo signals of the high-frequency ground wave radar is completed, the combined CFAR (constant false alarm rate) detection and target parameter estimation of a three-dimensional search space of the radial distance, the radial speed and the real speed are carried out, the detection probability of the real target is further improved by increasing the real speed spectrum information, the performance advantage is higher, the detection probability of the high-speed moving target of the high-frequency ground wave radar can be effectively improved, and the false-missing probability is reduced.

The manner in which the various steps shown in fig. 1 are performed is described below.

Optionally, in step S1, obtaining a high-frequency ground wave radar pulse pressure signal S_c(t_mτ) is:

wherein, t_m＝mT_r(M-0, 1.., M-1) represents a slow time, M is a high-frequency ground wave radar pulse accumulation number, and T is_rIs the pulse period of high-frequency ground wave radar, tau represents fast time, K is the target number, A_i1The pulse pressure signal amplitude of the ith target high-frequency ground wave radar is represented by B, the transmission signal bandwidth of the high-frequency ground wave radar is represented by c, the light speed is represented by c/f_cRepresenting the radar wavelength, f, of high-frequency ground waves_cFor high frequency ground wave radar carrier frequency, r_i(t_m) Is the radial distance equation for the ith target.

Optionally, for step S2, setting search parameters of a three-dimensional joint search of a radial distance, a radial velocity, and a true velocity, including:

and step S2-1, initializing search parameters according to the high-frequency ground wave radar parameters, and determining the search ranges of the radial distance, the radial speed and the real speed of the target.

According to the power range 0-R of high-frequency ground wave radar_maxSetting a radial distance search range r_min～r_max：

r_min＝0,r_max＝R_max

Unambiguous velocity measurement range from high-frequency ground wave radarSetting radial velocity search range

Wherein λ is the high-frequency ground wave radar wavelength, T_rThe pulse period of the high-frequency ground wave radar is, and M is the accumulation number of the high-frequency ground wave radar pulses;

detecting the maximum speed V of the target type (including sea surface ships and sea surface flying targets) according to the high-frequency ground wave radar_maxSetting a true velocity search range v_min～v_max：

v_min＝0,v_max＝V_max

And step S2-2, determining the search intervals of the radial distance, the radial speed and the real speed according to the high-frequency ground wave radar parameters.

Setting a search interval of a radial distance according to the size of a range gate of the high-frequency ground wave radar, wherein the search interval is expressed as:

wherein f is_sThe sampling rate of the high-frequency ground wave radar is shown, and c is the speed of light;

setting a radial velocity search interval according to the Doppler resolution of the high-frequency ground wave radar, wherein the radial velocity search interval is expressed as:

the search interval of the real velocity is consistent with the search interval of the radial velocity, that is, the velocity search interval is set according to the doppler resolution of the high-frequency ground wave radar, and is expressed as:

step S2-3, determining the search numbers of the distance, radial velocity and true velocity of the target, respectively expressed as:

wherein round (·) represents rounding operation, the rounding method is rounding, and M is the accumulation number of the high-frequency ground wave radar pulse;

step S2-4, obtaining the discretized search distance, the search radial velocity and the search real velocity, which are respectively expressed as:

r_n＝nΔr,n＝0,1,…,N_r-1

v_q＝qΔv,q＝0,1,…,N_v-1

completing search parametersAnd (4) setting.

Optionally, in step S3, performing three-dimensional joint search on the radial distance, the radial velocity, and the true velocity of the high-frequency ground wave radar pulse pressure signal, where the three-dimensional joint search includes:

the three-dimensional joint search definition formula of the radial distance, the radial speed and the real speed is obtained as follows:

where r represents the radial distance unit of the search,represents the radial velocity unit of the search, v represents the true velocity unit of the search,indicates a search parameter ofThe coherent accumulation amplitude value;

substituting high-frequency ground wave radar pulse pressure signal s_c(t_mτ) expression, there is:

wherein the content of the first and second substances,t representing search_mThe radial distance value at the moment.

As can be seen from the above formula, only in each pulse period t_mTime, r (t)_m) And r_i(t_m) At constant time, there is an accumulated peak; at the same time, r in the phase term_i(t_m)-r(t_m) The square error formula is used for expansion:

can obtain r (t)_m) And r_i(t_m) And the constant time has an accumulated peak value, which is equivalent to the time when the target parameters of the search detection domain are consistent.

Optionally, regarding step S4, performing target track signal extraction of the high-frequency ground wave radar according to the search parameter includes:

searching for parametersIn the case, the number of cross-distance units of the echo envelope of each pulse period is calculated, and the expression is as follows:

round (·) represents the rounding operation, and the rounding method is rounding;

aligning each pulse period echo envelope to a distance unit where an initial radial distance is located, and finishing target track signal extraction of the high-frequency ground wave radar, wherein the expression is as follows:

s(t_m)＝s_c(t_m,k(t_m))

wherein, s (t)_m) Represents the extracted t_mTemporal target trajectory signal, i.e. extracted high-frequency ground wave radar target t_mTarget trajectory at a time. By aligning the echo envelope at the initial radial range unit, range migration is also avoided.

Optionally, in step S5, a phase compensation function is constructed along the slow time dimension of the high-frequency ground wave radar, where the expression is:

wherein phi (t)_m) Represents t_mPhase compensation functions corresponding to the moments;

in step S6, the echo envelopes of the compensated target track signals are added in phase to complete coherent accumulation, where the expression is:

wherein the content of the first and second substances,indicates a search parameter ofThe coherent accumulated amplitude values.

Optionally, in step S7, setting a detection parameter, performing constant false alarm rate detection based on the result of coherent accumulation, and determining whether a target is detected, if yes, executing the next step, including:

step S7-1, initializing detection parameters and setting false alarm probability P_faIs divided intoSetting the number of reference units and protection units according to the number of units occupied by the target peak value which completes coherent accumulation in the detection domain in three detection domains, namely a radial distance domain, a radial speed domain and a real speed domain; the protection unit is a left unit and a right unit which are adjacent to each other in the detection domain, the reference unit is arranged at the outer side of the protection unit, namely at two sides far away from the detection unit, and the integral multiple of 2 is generally selected, such as 8, 16 and 32;

step S7-2, respectively in three detection domains of radial distance domain, radial velocity domain and real velocity domain, according to the number of reference units and false alarm probability P_faCalculating a corresponding CFAR threshold factor, wherein the expression is as follows:

where T represents the corresponding CFAR threshold factor in a detection domain, N_cRepresenting the number of reference cells in the detection domain;

step S7-3, calculating a noise floor according to the detecting unit and the plurality of reference units in the three detecting domains of the radial distance domain, the radial velocity domain and the real velocity domain, wherein the noise floor is equal to the sum of the coherent accumulation echo amplitudes corresponding to each reference unit in one detecting domain and then divided by the number of the reference units, that is, the average of the reference units in the radial velocity domain, the radial distance domain and the real velocity domain is taken as the noise floor of the domain, and the expression is:

wherein N is a corresponding noise floor in a detection domain,summing the amplitude of the phase-coherent accumulation echo corresponding to each reference unit;

step S7-4, calculating the detection threshold corresponding to the detection unit in three detection domains of a radial distance domain, a radial speed domain and a real speed domain, wherein the expression is as follows:

S＝T*N

wherein, S is a corresponding detection threshold in a detection domain, T is a corresponding CFAR threshold factor in the detection domain, and N is a corresponding noise floor in the detection domain;

step S7-5, judging whether coherent accumulation echo amplitudes of the detection unit in three detection domains of a radial velocity domain, a radial distance domain and a real velocity domain all exceed corresponding detection thresholds, if so, judging the detection unit to be a peak value unit, and if not, judging the detection unit to be a target;

and S7-6, judging whether all the detection units are traversed or not, if so, executing the next step, otherwise, stepping the detection units, and returning to the step S7-2.

Alternatively, in step S8, when performing parameter estimation on the detected target, the peak target parameter estimation value in each detection domain is obtained by a three-point secondary interpolation method. The peak formed by the target coherent accumulation usually occupies several cells, so if a peak is encountered in the accumulated result, it may be the target, which is referred to herein as the peak target; and the target peak is amplitude information of a cell having the largest amplitude among the several cells, i.e., the target peak.

Parameter estimation in a detection domain by three-point quadratic interpolation includes:

when the peak value corresponding to the target appears in the J-th unit, three-point secondary interpolation is carried out by utilizing the coherent accumulation amplitude of the J-th unit where the peak value is located, the coherent accumulation amplitude of the J-1-th unit adjacent to the peak value and the coherent accumulation amplitude of the J + 1-th unit adjacent to the peak value, the parameter value corresponding to the unit where the maximum value is located is estimated to serve as the estimated value of the peak value target parameter in a detection domain, and the expression is as follows:

wherein the content of the first and second substances,representing the magnitude, x, of the peak target parameter estimate in a detection domain_JThe parameter value of the J-th unit is shown, and f (J) shows the coherent accumulation amplitude of the J-th unit.

By adopting the mode, the estimated value of the peak target parameter is calculated in three detection domains, namely a radial distance domain, a radial speed domain and a real speed domain, so that the estimated radial distance, the estimated radial speed and the estimated real speed can be obtained.

Optionally, in step S8, performing parameter estimation on the detected target includes:

for the three-dimensional unit (i, j, k) detected as the target, the preliminary estimation values of the target radial distance, the radial velocity and the real velocity can be calculated as follows:

wherein the content of the first and second substances,a preliminary estimated radial distance is represented and,which represents the preliminary estimated radial velocity,representing the preliminary estimated true velocity.

After the initial estimation value is obtained, correction can be carried out through a three-point secondary interpolation method.

The invention also verifies the performance of the provided weak target accumulation detection method for the high-frequency ground wave radar. As shown in fig. 2(a) to 5, the MTD (moving target detection) method and the high frequency ground wave radar weak target accumulation detection method (CVGRFT method for short) provided by the present invention are respectively performed on 5120 pieces of high frequency ground wave radar measured pulse data to obtain RD graphs, which are respectively shown in fig. 2(b) and 2(a), CFAR detection based on CVGRFT three detection domains is performed on the accumulated result, a reference unit, a protection unit and CFAR threshold factors are respectively determined in three detection domains of a radial distance domain, a radial speed domain and a real speed domain, the detection results are shown in fig. 3 to 5, as can be seen from the detection results, 10 targets are detected by the MTD method altogether, and 16 targets are detected altogether under the accumulation of the CVGRFT method, wherein 10 targets detected after the MTD method accumulation can be detected under the accumulation condition of the present invention, and the snr of 6 targets after the MTD accumulation does not exceed the detection threshold, the method can be correctly detected under the condition of the method, so that the method has the function of measuring the real speed of the target for a high-frequency ground wave radar system, and can effectively improve the coherent accumulation performance of the high-speed weak target and further improve the detection probability of the high-speed weak target. FIG. 6 shows a real velocity spectrum of a target drawn by a high-frequency ground wave radar weak target detection method, corresponding to a velocity measurement function. The speed measurement result is 262.9m/s, the peak value of the radial velocity is-129.2 m/s, and the target moves away from the radar. Under the slicing of real speed and radial distance, the radial speed spectrum is compared, fig. 7 shows that the performance of the high-frequency ground wave radar weak target accumulation detection method is compared with that of the existing radial uniform motion phase-coherent accumulation method (namely, an MTD method, a Keystone transform-based phase-coherent accumulation method, namely a KT method, a Radon Fourier transform-based phase-coherent accumulation method, namely an RFT method), under the condition of the same accumulation duration, the CVGRFT method accumulates a peak value of 113.7dB, the RFT method accumulates peak values of 109.5dB, the KT accumulation peak value is 109.2dB, and the MTD method accumulates a peak value of 109.3 dB.

The embodiment of the invention also provides computing equipment which comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to realize the weak target accumulation detection method of the high-frequency ground wave radar in any embodiment of the invention.

The embodiment of the invention also provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the processor is enabled to execute the weak target accumulation detection method of the high-frequency ground wave radar in any embodiment of the invention.

Specifically, a system or an apparatus equipped with a storage medium on which software program codes that realize the functions of any of the above-described embodiments are stored may be provided, and a computer (or a CPU or MPU) of the system or the apparatus is caused to read out and execute the program codes stored in the storage medium.

In this case, the program code itself read from the storage medium can realize the functions of any of the above-described embodiments, and thus the program code and the storage medium storing the program code constitute a part of the present invention.

Examples of the storage medium for supplying the program code include a floppy disk, a hard disk, a magneto-optical disk, an optical disk (e.g., CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW), a magnetic tape, a nonvolatile memory card, and a ROM. Alternatively, the program code may be downloaded from a server computer via a communications network.

Further, it should be clear that the functions of any one of the above-described embodiments may be implemented not only by executing the program code read out by the computer, but also by causing an operating system or the like operating on the computer to perform a part or all of the actual operations based on instructions of the program code.

Further, it is to be understood that the program code read out from the storage medium is written to a memory provided in an expansion board inserted into the computer or to a memory provided in an expansion module connected to the computer, and then causes a CPU or the like mounted on the expansion board or the expansion module to perform part or all of the actual operations based on instructions of the program code, thereby realizing the functions of any of the above-described embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.