阅读说明：本技术 海洋和电离层一体化探测接收系统控制及信号处理系统 (Control and signal processing system of ocean and ionosphere integrated detection receiving system ) 是由 于长军 宋圳 王霖玮 刘爱军 吕哲 于 2021-08-26 设计创作，主要内容包括：本发明属于电磁波技术领域,公开了一种海洋和电离层一体化探测接收系统控制及信号处理系统,所述海洋和电离层一体化探测接收系统控制及信号处理系统,包括总控制子系统、天线开关控制器、接收机开关控制器以及显示控制子系统；总控制子系统、天线开关控制器以及接收机开关控制器的工作状态由以太网和显控平台连接,并显示在显控平台中；各个子系统通过网线与系统控制子系统连接,完成网络连接,建立与控制。本发明通过设计海洋信息-电离层一体化探测系统的接收系统控制方法以及信号处理方法,结合磁天线特有的特性,实现电离层垂测和海洋信息的同步获取,避免了两者之间的相互干扰,能够实时获得电离层的距离、多普勒频率以及空间分布情况。(The invention belongs to the technical field of electromagnetic waves, and discloses a control and signal processing system of an integrated detection receiving system of a sea and an ionized layer, which comprises a master control subsystem, an antenna switch controller, a receiver switch controller and a display control subsystem; the working states of the master control subsystem, the antenna switch controller and the receiver switch controller are connected with the display control platform through the Ethernet and are displayed in the display control platform; each subsystem is connected with the system control subsystem through a network cable to complete network connection and establish and control. By designing a receiving system control method and a signal processing method of the ocean information-ionosphere integrated detection system and combining the special characteristics of the magnetic antenna, the invention realizes the synchronous acquisition of ionosphere vertical measurement and ocean information, avoids the mutual interference between the ionosphere vertical measurement and the ionosphere vertical measurement, and can obtain the distance, Doppler frequency and space distribution condition of the ionosphere in real time.)

1. A control and signal processing system of an integrated detection receiving system of ocean and ionized layer is characterized in that the control and signal processing system of the integrated detection receiving system of ocean and ionized layer comprises a master control subsystem, an antenna switch controller, a receiver switch controller and a display control subsystem; the working states of the master control subsystem, the antenna switch controller and the receiver switch controller are connected with the display control platform through the Ethernet and are displayed in the display control platform; each subsystem is connected with a system control subsystem through a network cable to complete network connection and establish and control;

the master control subsystem is used for controlling the switch of the receiving wave gate of the antenna and the receiver through hardware programming;

the antenna switch controller and the receiver switch controller are used for receiving control signals and controlling the opening and closing of the antenna and the receiver; after storing a certain amount of data, the signal processor processes signals according to a signal processing principle to obtain ionosphere information;

and the display control subsystem, namely a display control platform, is connected with each part and subsystem through the Ethernet and is used for being responsible for the visualization of a control interface, the monitoring of equipment states and the storage and display of detection results of the master control system.

2. The system for controlling and processing the signals of the integrated detection and receiving system of the ocean and the ionosphere according to claim 1, wherein the total control subsystem is used for realizing parameter control of the offshore target detection signals, parameter control of the ionosphere detection signals and time sequence parameter control of the time sequence control subsystem; the ionosphere-offshore target detection synchronous control is realized through a control program of the master control subsystem, and an operation interface is displayed in the display control subsystem and is operated on the interface; the timing control design principle of the receiving system is as follows: receiving synchronization with the existing HFSWR time sequence to ensure the priority of the work task of the radar;

the main control subsystem takes a computer host as a main body, and the control mode of the ocean-ionosphere detection system is embodied in the main control subsystem; the synchronous working time sequence control and the detection signal frequency control of other subsystems are completed by writing programs and establishing network communication with the Ethernet and other subsystems.

3. The integrated ocean and ionosphere exploration receiver system control and signal processing system according to claim 1, wherein said antenna switch controller and receiver switch controller are used for controlling the opening and closing of the receiving wave gate by receiving the master control subsystem control signal; when the transmitter of the radar and the vertical measuring instrument transmits signals, the antenna and the receiver of the receiving system are closed, and when one pulse of the transmitter is transmitted, the switch of the antenna and the receiver is opened to receive echo signals; the controller is mainly realized by a time sequence synchronous control module, takes the time sequence controller as a core, takes the ARM and the FPGA as main bodies, utilizes the GPIO interface of the FPGA to generate a plurality of paths of time sequence control signals which can be configured by software, and respectively provides synchronous working time sequences and trigger signals for the antenna and the switch controller of the receiver.

4. The integrated ocean and ionospheric sounding receiver system control and signal processing system of claim 1 wherein the display control subsystem is a platform for user interaction, implemented using a general purpose computer, for displaying the operating state monitoring information status of each subsystem, the assignment of parameters and control information, ionospheric sounding results display, ocean information sounding results RD spectrum display, frequency preference results, ocean-ionospheric dynamics analysis results, and the system status report also displayed at the subsystem.

5. The system of claim 3, wherein in the timing synchronization controller, the timing controller generates each path of timing signals through the FPGA after receiving timing parameters sent by the upper computer, and connects to each subsystem through the GPIO interface in response; after each subsystem receives the corresponding analog control signal, starting a corresponding working mode; wherein the timing parameters include a trigger signal, a pulse width of a synchronization signal, and a length of time for which a transmitter is turned on or off.

6. A control and signal processing method of an integrated detection and reception system of the ocean and the ionosphere, which implements the control and signal processing system of the integrated detection and reception system of the ocean and the ionosphere according to any one of claims 1 to 5, the control and signal processing method of the integrated detection and reception system of the ocean and the ionosphere comprises the following steps:

firstly, a master control subsystem controls the switch of an antenna and a receiving wave gate of a receiver by using hardware programming to realize parameter control of an offshore target detection signal, parameter control of an ionosphere detection signal and time sequence parameter control of a time sequence control subsystem; generating a plurality of paths of timing control signals which can be configured by software by utilizing a GPIO (general purpose input/output) interface of the FPGA through a timing synchronization controller, and respectively providing synchronous working timing and trigger signals for an antenna and a receiver switch controller;

secondly, the radar transmitter detects signals of the P4 code, and the transmitter of the vertical measuring instrument filters the linear frequency modulation detection signals through respective power amplifiers and respective band-pass filters, and then sends the signals through respective transmitting antennas; receiving control signals through respective antenna switch controllers and respective receiver switch controllers, and controlling the antennas and the receivers to be switched on and off;

after receiving the echo by the receiving antenna, carrying out digital sampling from the receiver, and sending the echo data to a signal processing and data processor for analysis after down-conversion; after storing a certain amount of data, the signal processor processes signals according to a signal processing principle to obtain ionosphere information;

step four, the echo receiving part consists of two sets of equipment: firstly, a vertical measuring instrument receiving antenna and secondly, a uniform plane antenna array formed by a group of 16 magnetic antennas is adopted; the receiving antenna of the vertical measuring instrument keeps the original working mode of receiving the echo of the vertical measuring instrument, and the magnetic antenna planar array can issue a command through the master control to switch the working mode; the working time sequence of the antenna array is started by GPS synchronous triggering, ionosphere echo of a radar or echo of a vertical measurement instrument is selected to be received by selecting the working time sequence, working frequency and pulse width information of a following radar or the vertical measurement instrument, and the ionosphere is detected in space position;

and fifthly, the display control subsystem is connected with all the parts and subsystems by utilizing the Ethernet to carry out data interaction, so that the processing of echo signals, the visualization of a control interface of the master control system, the monitoring of equipment states and the storage and display of detection results are realized.

7. The method as claimed in claim 6, wherein in the step one, in the general control subsystem, the HFSWR radar multi-purpose pulse system working mode, the pulse repetition period relation of two detection signals is designed as follows:

PRT_ionosphere＝N×PRT_Oceans，N＞1；

Wherein, PRT_IonosphereFor ionospheric probe pulse repetition period, PRT_OceansDetecting the pulse repetition period for the ocean information, wherein N is a positive integer; when the respective transmitting system is closed, the receiving system starts to work; the working mode of the magnetic antenna array is controlled by the system issued command, and the corresponding working mode and time sequence are determined by an external trigger mode; and when the ionosphere detection is carried out for frequency sweeping, skipping 1-2 frequency points close to the ocean detection signal.

8. The method as claimed in claim 6, wherein in the second step, the transmitted signal in a pulse is set as s (t), and the expression of s (t) is:

wherein, P represents the number of P4 codes in a pulse, T is the width of a code, namely the width of a pulse is PT; rect (-) represents a rectangular function,f_cis the carrier frequency of the signal and,is a phase encoding value, i ═ 0,1, …, P-1; let the pulse repetition period be T_sThe probe waveform is represented as:

wherein n is the number of pulses; the echo signal is represented as:

r(t)＝S(t-τ)exp(j(2πf_d(t+τ)))+n(t)；

where τ is the time delay, f_dFor Doppler shift, n (t) is additive white Gaussian noise;

the processing of the echo data is as follows: firstly, pulse compression is carried out, and then coherent accumulation is carried out to obtain a range-Doppler spectrum of target information; the P4 code has good self-correlation characteristic, and during pulse compression, a transmitting signal is used as a reference signal and is subjected to correlation processing with an echo signal to obtain distance information; the correlation operation is as follows:

wherein r is_r(t) is the distance spectrum; r is_r(t) dividing by the number of pulses into n parts, namely:

r_r(t)＝[r_r1(t),r_r2(t),...,r_rn(t)]；

the split distance spectra are rearranged to:

performing FFT processing on the distance spectrums of a plurality of signal periods according to columns to obtain Doppler information of a target; the result obtained after two-dimensional processing is a range-doppler spectrum.

9. The method as claimed in claim 6, wherein in step five, the ionosphere probe signal emitted from the vertical measuring instrument is a chirp signal pointing vertically to the sky, and the waveform expression is:

wherein f (n) ═ f_cN is the carrier frequency, f is the carrier frequency, N is 1,2_cIs the initial carrier frequency, delta f is the step frequency interval, n is the nth pulse number; k is the frequency modulation slope, B is the signal bandwidth, and T is the signal period; the ionospheric echo signal is represented as:

r(t)＝s(t+τ)+n(t)；

wherein, tau is time delay, n (t) is additive white Gaussian noise; calculating the cross-correlation of r (t) with s (t) yields:

the time delay tau of the ionosphere echo can be obtained by searching the extreme value of R (u)_iIonospheric virtual height h ═ c τ_i2; respectively processing echo signals with different frequencies to obtain an ionosphere echo spectrogram;

obtaining the maximum electron concentration of each layer according to the reflection trace in the ionosphere echo spectrogram, wherein the maximum plasma frequency corresponding to the layer is as follows:

a group of equipment for receiving ionosphere echoes is added, 16 magnetic antennas are used as array elements to form a 4 x 4 uniform antenna planar array, the normalized gain of a directional pattern of the magnetic antennas in the zenith direction is 1, the ionosphere echoes in the zenith direction can be received, and two-dimensional wave beams in the horizontal and pitching directions of the planar array antennas are formed, so that the position of the ionosphere can be further positioned on the basis of distance information;

the array element 1 is a reference phase reference point and is located at an origin position, the whole planar array is located on an xoy plane, and the working modes are divided into the following two types:

mode 1, synchronous with the detection of an offshore target, namely synchronous with a radar working system; setting the local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system to be the same as the receiving local oscillation signal and the receiving frequency of the offshore target detection and to be synchronous with the time sequence; the difference of the directional diagrams of the magnetic antenna and the electric antenna enables the echo gain in the zenith direction or other high-altitude directions to be improved, and the ionized layer echo can be received more effectively; the method for obtaining the range-Doppler spectrum by signal processing is the same as that of the offshore target detection subsystem;

2-dimensional space beam forming is carried out on echo data by taking an ionosphere echo point, and the direction of an incoming wave is assumed to beWherein the content of the first and second substances,for pitch angle, θ ∈ [0,2 π ]]Is the pitch angle of the signal; defining the position of array element as c_n＝(x_n,y_n) Unit vector of far field signal isThe phase difference of the array element n with respect to the origin of coordinates is expressed as:

wherein λ is the wavelength of the electromagnetic wave; planar array steering vector extrapolation:

to pairWeight vector when directional incoming wave is used for beam forming ^*Representing taking conjugation; according to the principle of pattern multiplication, the beamforming expression is:

wherein the content of the first and second substances,the directional diagram of a single magnetic antenna array element;

performing dimensionality reduction processing in consideration of the spatial complexity of 2-dimensional beam forming; the E-plane directional pattern of the magnetic antenna is in an 8-shaped shape; for any one pitch angleThe horizontal angle of the directional diagram on the E surface is related to the horizontal angle; the H-plane directional diagram of the magnetic antenna is a circle, and for any horizontal angle theta', the direction gain of the H-plane directional diagram is a circle with the normalized amplitude smaller than 1 and is independent of the pitch angle; namely, the pitch angle does not influence the beam forming result of the horizontal angle, and two beam forming results in the horizontal direction and the pitch direction can be respectively obtained to obtain two groups of azimuth information; the calculation steps are as follows:

(1) calculating and obtaining parameters, including the spatial position of the array element of the magnetic antenna, selecting a reference antenna as a coordinate 0 point to perform two-dimensional uniform planar array arrangement to obtain the spatial position coordinate of the array element, and selecting a wavelength, a pulse repetition period and a transmission beam pointing parameter according to a working mode;

(2) performing signal processing of pulse compression and coherent accumulation on echo data to obtain an RD spectrum; selecting a target point from the RD spectrum to obtain target point data;

(3) copying multiple copies of echo data, and for directional antennas, beam forming must be limited within a certain spatial range; deviation from normal direction not more than + -20^°The correct beam forming result can be ensured; weighting a plurality of angle values near the pointing angle of the transmitting beam according to the pointing direction of the transmitting beam by the weighting vector angle;

(4) the beam forming in the horizontal direction is performed, and the beam forming result without influencing the horizontal angle by the pitch angle is fixedTemporary fetchingAn E surface directional diagram of the magnetic antenna is not an omnidirectional directional diagram, and a directional function of an array element needs to be considered; the normalized directivity shape function of the magnetic antenna isSubstituting into a beam forming formula, and calculating to obtain theta of a horizontal angle₀The beam forming result of (a);

(5) making beam forming in the pitching direction to make theta equal to theta₀，θ₀＝θ₀I.e. equivalent to multiplying the weight vector by a factor theta₀The resulting loss of the weighting is lost,calculating to obtain a beam forming result in the pitching direction;

calculating to obtain beam forming results of a plurality of spatial angles according to a beam forming calculation method, and finally obtaining spectral data of distance-speed-spatial orientation three-dimensional information so as to complete positioning of the space position of the ionosphere;

mode 2, synchronizing with the working mode of the plumb measuring instrument; setting the local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system to be the same as the receiving local oscillation signal and the receiving frequency of the vertical measuring instrument and to be synchronous with the time sequence; the receiving antenna of the vertical measuring instrument can only receive ionosphere echo in a single direction of the zenith, and when the vertical measuring instrument works, the transmitted signal can leak in other directions; when the receiving antenna array is added, echoes of transmitting signals in other directions can be received, so that ionospheric echoes except the zenith direction can be received, the ionospheric detection space range is expanded, and the signal processing mode is the same as that of the mode 1; compared with a vertical measuring instrument, the mode can obtain the ionosphere height, namely distance information, and can also obtain spatial distribution information and Doppler information;

the two working modes are controlled by parameters sent by the master control system to switch the working modes when the whole detection equipment is started;

for a 4 x 4 planar array, acquiring ionosphere spatial orientation information by adopting a two-dimensional MUSIC method; after more pulse compression and coherent accumulation data are obtained, selecting a data point corresponding to an ionosphere echo in each group to realize two-dimensional super resolution; the steering vector of the array is the same as the steering vector during beam forming, and the expression is as follows:

ionospheric echo signals are regarded as far-field narrow-band signals; setting the ionosphere orientation in space toIonospheric echo is the aforementioned r (t); the amplitude of the echo received by the magnetic antenna is modulated by a direction diagram; the expression of the echo received by the nth array element is as follows:

wherein n (t) is 0-mean Gaussian white noise; k ionospheric echoes are observed in the RD spectrum in total with the azimuth ofThe received signal expression of the whole planar array is:

X(t)＝A(t)S(t)+N(t)；

in the formula:

X(t)＝[x₁(t),x₂(t),...,x_N(t)]^T

accepting a data vector for the N dimension;

is a signal vector;

a steering vector for the received data; n (t) is Gaussian white noise; after a receiving signal model with an array element antenna as a magnetic antenna is constructed, calculating according to a two-dimensional MUSIC algorithm; the method comprises the following steps:

(1) calculating covariance matrix of received signal R (t) E (X (t)^T) E represents expect;

(2) decomposing the characteristic values of R (t), arranging the characteristic values from large to small and arranging the corresponding characteristic vectors from large to small; selecting a vector space formed by stretching the eigenvectors corresponding to the first k large eigenvalues as a signal subspace and recording the signal subspace as U_sThe rest of the feature vectors are noise subspaces and are marked as U_n；

(3) From the orthogonality of the signal subspace and the noise subspace,at U_nShould be 0, the expression should be a minimum, and the solution should be takenTurn into the following numbersThe study problem is as follows:

(4) taking the reciprocal of the formula in the step (3) to obtain the formulaThe two-dimensional peak expression of (a):

the data is firstly processed by beam forming to obtain the approximate spatial angle range of the ionized layer, and then the super-resolution processing is carried out in the range.

Technical Field

The invention belongs to the technical field of electromagnetic waves, and particularly relates to a control and signal processing system of an integrated detection receiving system of an ocean and an ionized layer.

Background

Currently, radar is a powerful tool for locating targets, acquiring speed information and azimuth information based on the principle of spatial electromagnetic wave transmission. During the second war, radar has been used to acquire hostile target information. In the HF band, electromagnetic waves can be diffracted and propagated along the surface, so that a radar operating in the HF band, which is called a high frequency ground wave radar (HFSWR), has the capability of beyond-the-horizon detection. For HFSWR, the performance of detecting targets is mainly constrained by three disadvantages: the method comprises the steps of firstly, interference and noise of other electromagnetic waves in space, secondly, ionosphere echo and thirdly, sea clutter. Usually, radar scholars regard ionospheric echo as a disturbance item for target detection, but ionospheric echo containing ionospheric information is valuable data for scholars studying ionospheric motion, and currently, few means for acquiring ionospheric information are available, and equipment capable of acquiring ionospheric and marine target information at the same time is lacking. Meanwhile, the change of the ionosphere is usually related to the change of natural information of the sea, for example, the common tsunami in the century can simultaneously excite the characteristic change of the sea and the ionosphere when the change occurs, and a certain linkage relation is formed between the ionosphere and the ionosphere, so that powerful information is provided for typhoon prediction, tsunami early warning and the like. China has achieved a lot of achievements today from the 80 th century of the past to develop a new system HFSWR. However, the existing HFSWR does not have the capability of synchronously performing sea surface target, offshore high altitude target information acquisition and ionosphere information acquisition. Therefore, the advantages of different detection devices need to be integrated, the advantages of radar networking are fully utilized, a new integrated detection system HFSWR for the over-the-horizon target, the ocean and the ionized layer above the ocean is constructed, the ocean and the ionized layer are taken as a mutually-associated whole, and ocean information (ocean current, wind field and wave field) and the ionized layer are synchronously acquired(ionospheric doppler shift, critical frequency F of layer F2₀F2, electron concentration, ionosphere height, etc.), and a more complete ocean-ionosphere information acquisition system in the time-space domain is constructed.

During ionospheric sounding, a large bandwidth frequency scan is required to determine its critical frequency. When the offshore target is detected, observation and accumulation are needed to be carried out at a certain fixed frequency. This causes two problems. Firstly, the working frequencies of the offshore target and the ionosphere information detection equipment are not allowed to be the same, and the offshore target and the ionosphere information are required to be detected simultaneously, so that when the two detection equipment are networked, a strict working time sequence corresponding relation is required. Secondly, in order to obtain the spatial distribution of the ionosphere, a group of planar array antennas is needed to obtain two-dimensional angle information, the two-dimensional beamforming and super-resolution processing involve complex calculation amount, and how to optimize the signal processing is also a difficulty.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) currently, there is no device that can simultaneously acquire ionospheric and offshore target information. The existing HFSWR does not have the capability of synchronously acquiring information of a sea surface target, an offshore high-altitude target and ionosphere information.

(2) The two-dimensional beamforming and super-resolution processing involve a complex number of computations.

The difficulty in solving the above problems and defects is:

(1) the problem of synchronous working is solved, firstly a set of detailed control scheme needs to be designed, secondly, the original equipment needs to be modified on hardware, and the difficulty is high.

(2) The algorithmic reduction of beamforming and super-resolution processing is essentially a mathematical search for an optimization algorithm. The method can be improved on the basis of the existing dimension reduction processing algorithm, but most of the existing algorithms only aim at uniform linear arrays, and two-dimensional planar arrays are rarely discussed. The difficulty in improvement is great.

The significance of solving the problems and the defects is as follows:

(1) the significance of solving the synchronous working problem is that the information of the ionized layer and the sea is obtained simultaneously. The ionosphere change and the sea state change are inseparable, and the prior observation means cannot simultaneously observe the change states of the ionosphere change and the sea state change, so that the dynamic relation between the ionosphere change and the sea state change cannot be accurately analyzed. An observation platform and a data collection platform are provided for the dynamic analysis between the two. And the data collected by the platform can provide strong support for the establishment of prediction models of ionosphere change, ocean information change and the like.

(2) The two-dimensional beam forming and super-resolution by using the magnetic antenna equipment have the effect that the traditional ionosphere observation means (such as a vertical measuring instrument and the like) cannot acquire the spatial information of the ionosphere, and the equipment can make up the defect. In order to meet the real-time requirement of signal processing, a large amount of data accumulated within several minutes needs to be subjected to fast arithmetic processing. It is therefore necessary to explore a method for reducing the amount of calculation without losing the calculation accuracy.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a control and signal processing system of an integrated detection receiving system of an ocean and an ionized layer.

The invention is realized in this way, a control and signal processing system of an integrated detection receiving system of ocean and ionized layer, the control and signal processing system of the integrated detection receiving system of ocean and ionized layer comprises a master control subsystem, an antenna switch controller, a receiver switch controller and a display control subsystem; the working states of the master control subsystem, the antenna switch controller and the receiver switch controller are connected with the display control platform through the Ethernet and are displayed in the display control platform; each subsystem is connected with the system control subsystem through a network cable to complete network connection and establish and control.

The master control subsystem is used for controlling the switch of the receiving wave gate of the antenna and the receiver through hardware programming;

the antenna switch controller and the receiver switch controller are used for receiving control signals and controlling the opening and closing of the antenna and the receiver; after storing a certain amount of data, the signal processor processes signals according to a signal processing principle to obtain ionosphere information;

and the display control subsystem, namely a display control platform, is connected with each part and subsystem through the Ethernet and is used for being responsible for the visualization of a control interface, the monitoring of equipment states and the storage and display of detection results of the master control system.

Furthermore, the master control subsystem is used for realizing parameter control of the offshore target detection signal, parameter control of the ionosphere detection signal and time sequence parameter control of the time sequence control subsystem; the ionosphere-offshore target detection synchronous control is realized through a control program of the master control subsystem, and an operation interface is displayed in the display control subsystem and is operated on the interface; the timing control design principle of the receiving system is as follows: and the receiving synchronization with the conventional HFSWR time sequence ensures the priority of the work task of the radar.

The main control subsystem takes a computer host as a main body, and the control mode of the ocean-ionosphere detection system is embodied in the main control subsystem; the synchronous working time sequence control and the detection signal frequency control of other subsystems are completed by writing programs and establishing network communication with the Ethernet and other subsystems.

Further, the antenna switch controller and the receiver switch controller are used for controlling the opening and closing of the receiving wave gate by receiving a control signal of the master control subsystem; when the transmitter of the radar and the vertical measuring instrument transmits signals, the antenna and the receiver of the receiving system are closed, and when one pulse of the transmitter is transmitted, the switch of the antenna and the receiver is opened to receive echo signals.

Furthermore, the display control subsystem is a platform interacting with a user, is realized by using a general computer, and is used for displaying the working state monitoring information state, the assigned parameter and control information, the ionosphere detection result display, the ocean information detection result RD spectrum display, the frequency optimization result and the ocean-ionosphere dynamics analysis result of each subsystem, and is also responsible for processing the echo signal, and the state report of the system is also displayed in the subsystem.

The ocean information detection equipment is reconstructed based on radar and comprises an ocean information detection transmitter, a transmitting antenna, a receiving antenna, a receiver and a signal processing and data processing machine, wherein the transmitter transmits a P4 code detection signal to a power amplifier, filters the detection signal by a group of band-pass filters, and then transmits the detection signal through the transmitting antenna; after receiving the echo, the receiving antenna performs digital sampling from the receiver, and sends the echo data to a signal processing and data processor for analysis after down-conversion;

the ionosphere detection equipment is modified by a vertical measuring instrument, and ionosphere detection signals transmitted by the vertical measuring instrument are linear frequency modulation signals pointing to the sky vertically;

the time sequence synchronous control device takes the time sequence controller as a core, takes the ARM and the FPGA as main bodies, utilizes the GPIO interface of the FPGA to generate a plurality of paths of time sequence control signals which can be configured by software, and respectively provides synchronous working time sequences and trigger signals for the antenna and the receiver switch controller.

Furthermore, in the time sequence synchronous controller, after receiving time sequence parameters sent by the upper computer, the time sequence controller generates each path of time sequence signals through the FPGA and is connected to each subsystem through a GPIO interface in response; after each subsystem receives the corresponding analog control signal, starting a corresponding working mode; the time sequence parameters comprise a trigger signal, the pulse width of a synchronous signal and the opening and closing time length of a transmitter.

Another object of the present invention is to provide a method for controlling and processing signals of an integrated detection and reception system for the ocean and the ionosphere, which uses the system for controlling and processing signals of an integrated detection and reception system for the ocean and the ionosphere, wherein the method for controlling and processing signals of an integrated detection and reception system for the ocean and the ionosphere comprises the following steps:

the method comprises the following steps that firstly, a master control subsystem controls the switch of an antenna and a receiving wave gate of a receiver by utilizing hardware programming to realize parameter control of an offshore target detection signal, parameter control of an ionosphere detection signal and time sequence parameter control of a time sequence control subsystem; and a time sequence synchronous controller generates a plurality of paths of time sequence control signals which can be configured by software by utilizing a GPIO (general purpose input/output) interface of the FPGA, and provides synchronous working time sequences and trigger signals for receiving wave gates of an antenna and a receiver respectively. The step has the function of issuing control parameters for the antenna switch controller and the receiver switch controller, so that the receiving system is matched with the original radar system in time sequence, and the synchronous detection is ensured.

Secondly, the radar transmitter detects signals of the P4 code, and the transmitter of the vertical measuring instrument device filters the linear frequency modulation detection signals through respective power amplifiers and respective band-pass filters, and then sends the linear frequency modulation detection signals through respective transmitting antennas; receiving control signals through respective antenna switch controllers and respective receiver switch controllers, and controlling the antennas and the receivers to be switched on and off; the step is used for enabling the antenna switch controller and the receiver switch controller to work according to functions after receiving the control parameters, namely switching of the switch state.

And step three, the echo receiving part consists of two sets of equipment. The antenna array is a 4X 4 uniform plane antenna array formed by adopting a group of 16 magnetic antennas. The receiving antenna of the vertical measuring instrument keeps the original working mode of receiving the echo of the vertical measuring instrument, and the magnetic antenna planar array can issue commands through the master control to switch the working mode. Selecting to receive the ionized layer echo of the radar or the echo of the plumb measuring instrument by selecting the information of the following radar or the plumb measuring instrument, such as the working time sequence, the working frequency, the pulse width and the like, and detecting the space position of the ionized layer; the step has the function of defining the specific equipment type, the arrangement form and the respective function of the receiving antenna, and the antenna switch controller has a defined function object.

And step four, after the receiving antenna receives the echo, firstly, the receiver part carries out digital sampling, down-conversion and other processing on the analog signal, converts the data into a form which can be identified by a signal processing function and then sends the form to a signal machine for analyzing the echo data. After storing a certain amount of data, the signal processor performs signal processing according to a signal processing principle, and a specific processing mode is described later. This step has the effect of signal processing the received signal. In particular, by means of the echoes of the magnetic antenna array device, ionospheric spatial distribution information can be obtained in the processing results.

Connecting each part and each subsystem through the display control subsystem by using the Ethernet to perform data interaction, and realizing processing of echo signals, visualization of a control interface of a master control system, monitoring of equipment states and storage and display of detection results; the step has the effect of visualizing the issuing control parameters, the feedback results of the working states of all the submodules and the signal processing results, and more conveniently carrying out system regulation and control and analysis of echo information.

Further, in the first step, in the master control subsystem, the working mode of the HFSWR radar multi-purpose pulse system is designed to have a pulse repetition period relation of two detection signals as follows:

PRT_ionosphere＝N×PRT_Oceans，N＞1；

Wherein, PRT_IonosphereFor ionospheric probe pulse repetition period, PRT_OceansThe pulse repetition period is detected for ocean information, and N is a positive integer. When the respective transmitting system is closed, the receiving system starts to work; the working mode of the magnetic antenna array is controlled by the system issued command, and the corresponding working mode and time sequence are determined by an external trigger mode; and when the ionosphere detection is carried out for frequency sweeping, skipping 1-2 frequency points close to the ocean detection signal.

Further, in the second step, in the radar device, a sending signal in a pulse is set as s (t), and an expression of s (t) is as follows:

wherein, P represents the number of P4 codes in a pulse, T is the width of a code, namely the width of a pulse is PT; rect (-) represents a rectangular function,f_cis the carrier frequency of the signal and,is a phase encoding value, i ═ 0,1, …, P-1; let the pulse weightWith a complex period of T_sThe probe waveform is represented as:

where n is the number of pulses. The echo signal is represented as:

r(t)＝S(t-τ)exp(j(2πf_d(t+τ)))+n(t)；

where τ is the time delay, f_dFor Doppler shift, n (t) is white additive Gaussian noise.

The processing of the echo data is as follows: pulse compression is carried out firstly, and then coherent accumulation is carried out, so that the range-Doppler spectrum of the target information is obtained. The P4 code has good autocorrelation characteristic, and during pulse compression, the transmitted signal is used as a reference signal and is correlated with an echo signal to obtain distance information. The correlation operation is as follows:

wherein r is_r(t) is the distance spectrum; r is_r(t) dividing by the number of pulses into n parts, namely:

r_r(t)＝[r_r1(t),r_r2(t),...,r_rn(t)]；

the split distance spectra are rearranged to:

and performing FFT processing on the distance spectrums of a plurality of signal periods according to columns to obtain the Doppler information of the target. The result obtained after two-dimensional processing is a range-doppler spectrum.

Further, in the second step, the ionosphere detection signal emitted by the vertical measurement instrument is a chirp signal pointing to the sky vertically, and the waveform expression is as follows:

wherein f (n) ═ f_c+ N Δ f, N ═ 1,2 … N for the carrier frequency, f_cIs the initial carrier frequency, delta f is the step frequency interval, n is the nth pulse number; k is the frequency modulation slope, B is the signal bandwidth, and T is the signal period; the ionospheric echo signal is represented as:

r(t)＝s(t+τ)+n(t)；

wherein, τ is time delay, and n (t) is additive white Gaussian noise. Calculating the cross-correlation of r (t) with s (t) yields:

the time delay tau of the ionosphere echo can be obtained by searching the extreme value of R (u)_iIonospheric virtual height h ═ c τ_i2; respectively processing echo signals with different frequencies to obtain an ionosphere echo spectrogram;

obtaining the maximum electron concentration of each layer according to the reflection trace in the ionosphere echo spectrogram, wherein the maximum plasma frequency corresponding to the layer is as follows:

further, in the third step, 16 magnetic antennas are used as array elements to form a 4 × 4 uniform antenna planar array, the normalized gain of the directional diagram of the magnetic antennas in the zenith direction is 1, the echo of the ionosphere in the zenith direction can be received, and two-dimensional beam forming in the horizontal and pitching directions of the area array antenna is performed, that is, the position of the ionosphere can be further positioned on the basis of the distance information.

The array element 1 is a reference phase reference point and is located at an origin position, the whole planar array is located on an xoy plane, the working modes are divided into two types, and the two types are embodied in a signal processing part in the fourth step. The method is specifically divided into the following two modes:

mode 1, synchronous with offshore object detection. The local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system are set to be the same as the receiving local oscillation signal and the receiving frequency of the offshore target detection, and the time sequence is synchronous. The difference of the directional diagrams of the magnetic antenna and the electric antenna enables the echo gain in the zenith direction or other high-altitude directions to be improved, and the ionospheric echo can be received more effectively. The method for obtaining the range-doppler spectrum by signal processing is the same as that of the offshore target detection subsystem.

2-dimensional space beam forming is carried out on echo data by taking an ionosphere echo point, and the direction of an incoming wave is assumed to beWherein the content of the first and second substances,for pitch angle, θ ∈ [0,2 π ]]Is the pitch angle of the signal; defining the position of array element as c_n＝(x_n,y_n) Unit vector of far field signal isThe phase difference of the array element n with respect to the origin of coordinates is expressed as:

wherein λ is the wavelength of the electromagnetic wave; planar array steering vector extrapolation:

to pairWeight vector when directional incoming wave is used for beam forming ^*Representing taking conjugation; according to the principle of pattern multiplication, the beamforming expression is:

wherein the content of the first and second substances,is the directional diagram of a single magnetic antenna array element.

The dimensionality reduction is performed in consideration of the spatial complexity of the 2-dimensional beamforming. The E-plane pattern of the magnetic antenna is an "8" shape. For any one pitch angleThe horizontal angle of the pattern in the E plane is related to the horizontal angle. The H-plane directional pattern of the magnetic antenna is a circle, and the directional gain of the H-plane directional pattern is a circle with the normalized amplitude smaller than 1 for any horizontal angle theta', and is independent of the pitch angle. Namely, the pitch angle does not affect the beam forming result of the horizontal angle, and two beam forming results in the horizontal direction and the pitch direction can be respectively obtained to obtain two groups of azimuth information. The calculation steps are as follows:

(1) calculating and obtaining parameters, including the spatial position of the array element of the magnetic antenna, selecting a reference antenna as a coordinate 0 point to perform two-dimensional uniform planar array arrangement to obtain the spatial position coordinate of the array element, and selecting a wavelength, a pulse repetition period and a transmission beam pointing parameter according to a working mode;

(2) performing signal processing of pulse compression and coherent accumulation on echo data to obtain an RD spectrum; selecting a target point from the RD spectrum to obtain target point data;

(3) copying multiple copies of echo data, and for directional antennas, beam forming must be limited within a certain spatial range; the correct beam forming result can be ensured when the deviation from the normal direction is not more than +/-20 degrees; weighting a plurality of angle values near the pointing angle of the transmitting beam according to the pointing direction of the transmitting beam by the weighting vector angle;

(4) the beam forming in the horizontal direction is performed, and the beam forming result without influencing the horizontal angle by the pitch angle is fixedTemporary fetchingAn E surface directional diagram of the magnetic antenna is not an omnidirectional directional diagram, and a directional function of an array element needs to be considered; the normalized directivity shape function of the magnetic antenna isSubstituting into a beam forming formula, and calculating to obtain theta of a horizontal angle₀The beam forming result of (a);

(5) making beam forming in the pitching direction to make theta equal to theta₀，θ₀＝θ₀I.e. equivalent to multiplying the weight vector by a factor theta₀The resulting loss of the weighting is lost,and calculating to obtain a beam forming result in the pitching direction.

And calculating to obtain beam forming results of a plurality of spatial angles according to a beam forming calculation method, and finally obtaining spectral data of distance-speed-spatial orientation three-dimensional information so as to complete positioning of the spatial position of the ionosphere.

And 2, synchronizing the mode 2 with the working mode of the plumb measuring instrument. Setting the local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system to be the same as the receiving local oscillation signal and the receiving frequency of the vertical measuring instrument and to be synchronous with the time sequence; the receiving antenna of the vertical measuring instrument can only receive the ionosphere echo in the single direction of the zenith, and when the vertical measuring instrument works, the transmitted signal can leak in other directions. When the receiving antenna array is added, echoes of transmitting signals in other directions can be received, so that ionospheric echoes except the zenith direction can be received, the ionospheric exploration space range is expanded, and the signal processing mode is the same as that of the mode 1. Compared with a vertical measuring instrument, the mode can obtain the ionosphere height, namely distance information, and can also obtain spatial distribution information and Doppler information.

The two working modes are controlled by parameters sent by the master control system to switch the working modes when the whole detection equipment is started.

For a 4 x 4 planar array, acquiring ionosphere spatial orientation information by adopting a two-dimensional MUSIC method. After more pulse compression and coherent accumulation data are acquired, each group selects a data point corresponding to an ionosphere echo to realize two-dimensional super resolution. The steering vector of the array is the same as the steering vector during beam forming, and the expression is as follows:

ionospheric echo signals are treated as far-field narrowband signals. Setting the ionosphere orientation in space toThe ionospheric echo is the aforementioned r (t). The amplitude of the echo received by the magnetic antenna is modulated by the direction diagram. The expression of the echo received by the nth array element is as follows:

where n (t) is 0-mean Gaussian white noise. K ionospheric echoes are observed in the RD spectrum in total with the azimuth ofThe received signal expression of the whole planar array is:

X(t)＝A(t)S(t)+N(t)；

in the formula:

X(t)＝[x₁(t),x₂(t),...,x_N(t)]^T

accepting a data vector for the N dimension;

is a signal vector;

is a steering vector for the received data. N (t) is white Gaussian noise. And after constructing a receiving signal model with the array element antenna as the magnetic antenna, calculating according to a two-dimensional MUSIC algorithm. The method comprises the following steps:

(1) calculating covariance matrix of received signal R (t) E (X (t)^T) E represents expect;

(2) decomposing the characteristic values of R (t), arranging the characteristic values from large to small and arranging the corresponding characteristic vectors from large to small; selecting a vector space formed by stretching the eigenvectors corresponding to the first k large eigenvalues as a signal subspace and recording the signal subspace as U_sThe rest of the feature vectors are noise subspaces and are marked as U_n；

(3) From the orthogonality of the signal subspace and the noise subspace,at U_nShould be 0, the expression should be a minimum, and the solution should be takenThe problem of (2) translates into the following mathematical problem:

(4) taking the reciprocal of the formula in the step (3) to obtain the formulaThe two-dimensional peak expression of (a):

for super-resolution algorithms, in order to ensure that the signal-to-noise ratio of the data before processing is sufficiently large, it is not usually selected to reduce the number of fast beats to reduce the amount of calculation. One idea of reducing the amount of computation of super-resolution is to reduce the amount of computation by improving the angle search step size. Because the result of beam forming is existed before super-resolution processing, the prior information obtained by beam forming can be fully utilized. The method comprises the following steps: the beam forming is firstly carried out on the data to obtain the approximate spatial angle range of the ionized layer, and the calculated amount is greatly reduced by utilizing the prior information, namely, the angle search is carried out in the range instead of the whole angle space.

By combining all the technical schemes, the invention has the advantages and positive effects that: the invention provides a control and signal processing system of an integrated detection receiving system of ocean and ionosphere, in particular to a novel system sea detection high-frequency radar receiving system which can simultaneously complete the tasks of sea target detection and ionosphere information acquisition.

The invention designs a novel ocean-ionosphere information integrated detection high-frequency ground wave radar system by utilizing the advantages and the technology of radar networking according to the detection and receiving principles of the existing high-frequency ground wave radar, magnetic antenna array equipment and an ionosphere verticality measuring instrument, realizes the synchronous acquisition of ocean-ionosphere information, and provides powerful data support for the research of the dynamic relation between the ionosphere and the ocean.

The key innovation point of the invention is also the technical effect that a receiving system control method and a signal processing method of the ocean information-ionosphere integrated detection system are designed. The ionosphere vertical measurement and the ocean information are synchronously obtained by combining the special characteristics of the magnetic antenna, the mutual interference between the ionosphere vertical measurement and the ocean information is avoided, and the distance, Doppler frequency and space distribution condition of the ionosphere can be obtained in real time.

The ionosphere verticality measuring instrument is combined with the high-frequency ground wave radar and the magnetic antenna array, so that the ionosphere information and the ocean information can be synchronously acquired; one is that the receiving system is synchronous with the original radar and the original vertical measuring instrument through a system time sequence control method without mutual interference, and the ability of acquiring the ionosphere information in real time is increased from the time perspective; and secondly, aiming at the characteristic that the space directional diagram of the magnetic antenna is different from that of the omnidirectional antenna, the 2-dimensional beam forming method adopting the dimension reduction processing can save the computing capability on the premise of ensuring the measurement precision, and the super-resolution processing method is added to more finely acquire the space direction.

Drawings

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

Fig. 1 is a schematic structural diagram of a control and signal processing system of an integrated detection and reception system for the ocean and the ionosphere according to an embodiment of the present invention.

Fig. 2 is a timing relationship between subsystems of a control and signal processing system of an integrated detection and reception system for ocean and ionosphere according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of frequency variation of a transmission signal according to an embodiment of the present invention.

Fig. 4 is a diagram illustrating the autocorrelation of a P4 code waveform according to an embodiment of the present invention.

Fig. 5 is a 16-magnetic antenna array element arrangement diagram provided by the embodiment of the invention.

Fig. 6 is a schematic diagram of simulation of dual target echo RD spectra according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of simulation of horizontal angle beamforming according to an embodiment of the present invention.

Fig. 8 is a schematic diagram of a simulation of pitch angle beamforming provided by an embodiment of the present invention.

FIG. 9 is a schematic diagram of a two-dimensional super-resolution process according to an embodiment of the present invention.

Fig. 10 is a flowchart of a method for controlling and processing signals of an integrated detection and reception system for the ocean and the ionosphere according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In view of the problems in the prior art, the present invention provides a control and signal processing system for an integrated detection and reception system for ocean and ionosphere, and the present invention is described in detail with reference to the accompanying drawings and embodiments. The technical solution of the present invention is further described below with reference to the accompanying drawings.

Fig. 1 is a system block diagram of the receiving system, which includes a master control subsystem, an antenna switch controller, a receiver switch controller and a display control subsystem. The functions and principles of the modules in the invention are as follows: the master control subsystem controls the switch of the receiving wave gate of the antenna and the receiver through hardware programming; and the antenna switch controller and the receiver switch controller receive the control signal and control the opening and closing of the antenna and the receiver. After storing a certain amount of data, the signal processor starts to process signals according to the signal processing principle described above to obtain ionosphere information; the working states of the master control subsystem, the antenna switch controller and the receiver switch controller are connected with the display control platform through the Ethernet and are displayed in the display control platform; the display control platform is realized by using a general computer, and displays the working state monitoring information state, the assigned parameters and control information, the ionosphere detection result display, the ocean information detection result RD spectrum display, the frequency preference result and the ocean-ionosphere dynamics analysis result of each subsystem.

FIG. 2 is a diagram of the relationship between ionosphere detection and marine information detection timing sequences, wherein the ionosphere detection emission period is required to be an integral multiple of the marine information detection emission period. And when the radar transmits signals, the ionosphere detection system also needs to close the receiving equipment to prevent the devices from being damaged.

FIG. 3 is a diagram of ionosphere sounding versus marine information sounding frequency. If the radar equipment works at a certain frequency within a certain time, the simultaneous emission is guaranteed not to interfere with each other, and the working frequency of the vertical measuring instrument is required to be avoided. In this constraint relation, the receiving system strictly allocates the working time sequence according to the corresponding working mode, so as to ensure the normal operation of the whole system.

Fig. 5 is a schematic diagram of a spatial layout of a magnetic antenna receiving array in this embodiment. 16 magnetic antennas are distributed into a 4 multiplied by 4 uniform plane array, and the horizontal angle and the space angle of the incoming wave direction can be estimated by taking an origin antenna as a reference array element.

The technical solution of the present invention will be further described with reference to the following examples.

As shown in fig. 1, the system for controlling and processing signals of an integrated detection and reception system for ocean and ionosphere provided by the embodiment of the present invention includes a master control subsystem, an antenna switch controller, a receiver switch controller, and a display control subsystem; each subsystem is connected with the master control subsystem through a network cable to complete system control and information transmission.

And the master control subsystem is used for controlling the switch of the receiving wave gate of the antenna and the receiver through hardware programming. The main control subsystem is realized by a computer host, and a control program of the system is integrated in the computer. Parameters of antenna and receiver switch control programs are issued through the control programs, the parameters are transmitted through coding, and parameter data are decoded and read at a switch controller.

The antenna switch controller and the receiver switch controller are used for receiving control signals and controlling the opening and closing of the antenna and the receiver; the main control chip of the controller is ARM, is connected with the main control subsystem and the display control platform through Ethernet, receives the control instruction and the system parameters, and outputs the system state. And after receiving the signals transmitted by the master control subsystem, the ARM decodes and reads the parameters and distributes the parameters to the FPGA module. And through configuring FPGA parameters, controlling the FPGA to generate and output each sequential logic circuit, and feeding back the working state of each sequential logic circuit to an equipment state monitoring result interface in the master control subsystem.

The signal processor is implemented by a high-performance computer. And processing the signals received by the receiver. The receiver uses the FPGA module to process the received analog signal echo, including signal sampling, digital frequency conversion and the like, and the echo is processed into a form capable of being processed by a computer. After storing a certain amount of data, the signal processor processes signals according to the signal processing principle to obtain ionospheric space distribution information; the processed result is displayed in the display control subsystem, and the working state is fed back to the equipment state monitoring result interface in the master control subsystem.

And the display control subsystem, namely a display control platform, is connected with each part and subsystem through the Ethernet and is used for visualizing a control interface of the master control system, displaying the state monitoring results of all the subsystems and displaying the ocean information and the ionosphere detection results. The display control platform consists of 4 displays, and respectively displays a parameter setting interface, the working states of the master control subsystem and each system, a magnetic antenna array echo signal processing result graph (namely an RD spectrogram) and a verticality measuring instrument receiving antenna echo signal processing graph. The working states of the master control subsystem, the antenna switch controller and the receiver switch controller are connected with the display control platform through the Ethernet and are displayed in the display control platform;

as shown in fig. 10, the method for controlling and processing signals of an integrated detection and reception system of the ocean and the ionosphere according to the embodiment of the present invention includes the following steps:

s101, the master control subsystem controls the switch of an antenna and a receiving wave gate of a receiver by using hardware programming to realize parameter control of an offshore target detection signal, parameter control of an ionosphere detection signal and time sequence parameter control of a time sequence control subsystem; and a time sequence synchronous controller generates a plurality of paths of time sequence control signals which can be configured by software by utilizing a GPIO (general purpose input/output) interface of the FPGA, and provides synchronous working time sequences and trigger signals for receiving wave gates of an antenna and a receiver respectively.

S102, a transmitter of the radar system detects signals of the P4 code, and a transmitter of the vertical measuring instrument system filters and removes the chirp detection signals through respective power amplifiers and respective band-pass filters, and then sends the signals through respective transmitting antennas; receiving control signals through respective antenna switch controllers and respective receiver switch controllers, and controlling the antennas and the receivers to be switched on and off;

and S103, the echo receiving part consists of two sets of equipment. The antenna array comprises a vertical measuring instrument receiving antenna and a uniform plane antenna array formed by adopting a group of 16 magnetic antennas. The receiving antenna of the vertical measuring instrument keeps the original working mode of receiving the echo of the vertical measuring instrument, and the magnetic antenna planar array can issue commands through the master control to switch the working mode. Selecting to receive the ionized layer echo of the radar or the echo of the plumb measuring instrument by selecting the information of the following radar or the plumb measuring instrument, such as the working time sequence, the working frequency, the pulse width and the like, and detecting the space position of the ionized layer;

and S104, after the receiving antenna receives the echo, the receiver part performs digital sampling, down-conversion and other processing on the analog signal, converts the data into a form which can be identified by a signal processing function, and sends the form to a signal machine for analyzing the echo data. After storing a certain amount of data, the signal processor processes signals according to a signal processing principle, wherein a specific processing mode is the mode of the invention;

and S105, the display control subsystem is connected with all the parts and subsystems by utilizing the Ethernet to perform data interaction, so that the processing of echo signals, the visualization of a control interface of the master control system, the monitoring of equipment states and the storage and display of detection results are realized.

The system structure of the invention is shown in figure 1 and comprises a master control subsystem, an antenna switch controller, a receiver switch controller and a display control subsystem. The main control subsystem has the functions of parameter control of an offshore target detection signal, parameter control of an ionosphere detection signal and time sequence parameter control of a time sequence control subsystem, and ionosphere-offshore target detection synchronous control can be realized in a control program of the subsystem. The operation interface is displayed on the display control subsystem, and the operation can be carried out on the interface. The timing control design principle of the receiving system is as follows: and the receiving synchronization with the conventional HFSWR time sequence ensures the priority of the work task of the radar. And the antenna switch controller and the receiver switch controller receive the control signal of the master control subsystem to control the opening and closing of the receiving wave gate. When the transmitter of the radar and the vertical measuring instrument transmits signals, the antenna and the receiver of the receiving system need to be closed, and when one pulse of the transmitter is transmitted, the switch of the antenna and the receiver is opened to receive echo signals. The display control subsystem is a platform for interacting with a user and is also responsible for processing echo signals, and a status report of the system is also displayed in the subsystem. Each subsystem is connected with the system control subsystem through a network cable to complete network connection and establish and control.

The main control subsystem takes a computer host as a main body, and the control mode of the ocean-ionosphere detection system is embodied here. The synchronous working time sequence control and the detection signal frequency control of other subsystems are completed by writing programs and establishing network communication with the other subsystems by using Ethernet.

The logic relationship and the frequency relationship of the synchronous operation timing control design are shown in fig. 2 and 3. The HFSWR radar adopts a pulse system working mode. In order to ensure the synchronization between the two signals, the pulse repetition period relation of the two detection signals is designed as follows:

PRT_ionosphere＝N×PRT_Oceans，N＞1

Wherein, PRT_IonosphereFor ionospheric probe pulse repetition period, PRT_OceansThe pulse repetition period is detected for ocean information, and N is a positive integer. In the figure, example N is 2. It is also necessary for the receiving devices to satisfy a synchronization relationship in which the receiving systems start operating when the respective transmitting systems are turned off. The working mode of the magnetic antenna array is controlled by the system issued command, and the corresponding working mode and time sequence are determined by an external trigger mode. In order to avoid conflict and guarantee the premise of preferential detection of ocean information, 1-2 frequency points close to ocean detection signals need to be skipped when the ionosphere detection is carried out frequency sweeping.

The signal that the radar transmitted is P4 sign indicating number, and the transmitter passes through power amplifier with P4 sign indicating number detected signal, and after a set of band-pass filter filtration edulcoration, send out through transmitting antenna. After receiving the echo, the receiving antenna carries out digital sampling from the receiver, and the echo data is sent to a signal processing and data processing machine for analysis after down-conversion. Let the transmit signal in a pulse be s (t) whose expression is:

where P denotes the number of P4 codes in a pulse, and T is the width of a code, i.e., a pulse width PT. rect (-) represents a rectangular function,f_cis the carrier frequency of the signal and,i is 0,1, …, P-1. Let the pulse repetition period be T_sThe probe waveform can be expressed as:

where n is the number of pulses. The echo signal may be represented as:

r(t)＝S(t-τ)exp(j(2πf_d(t+τ)))+n(t)

where τ is the time delay, f_dFor Doppler shift, n (t) is white additive Gaussian noise. The processing of the echo data is as follows: pulse compression is carried out firstly, and then coherent accumulation is carried out, so that the range-Doppler spectrum of the target information is obtained. The P4 code has good autocorrelation characteristic (see figure 4), and during pulse compression, the transmitted signal is used as a reference signal and is correlated with the echo signal to obtain distance information. The correlation operation is as follows:

wherein r is_r(t) is the distance spectrum. r is_r(t) dividing by the number of pulses into n parts, namely:

r_r(t)＝[r_r1(t),r_r2(t),...,r_rn(t)]

the split distance spectra are rearranged to:

and performing FFT processing on the distance spectrums of a plurality of signal periods according to columns to obtain the Doppler information of the target. The result obtained after two-dimensional processing is a range-doppler spectrum.

The ionosphere detection signal emitted by the vertical measuring instrument is a linear frequency modulation signal which points to the sky vertically. The waveform expression is:

wherein f (n) ═ f_c+ N Δ f, N ═ 1,2 … N for the carrier frequency, f_cFor the initial carrier frequency, Δ f is the step frequency interval and n is the nth number of pulses. And K is the frequency modulation slope, B is the signal bandwidth, and T is the signal period. Similarly, the ionospheric echo signal can be expressed as:

r(t)＝s(t+τ)+n(t)

where τ is the time delay and n (t) is additive white gaussian noise. Calculating the cross-correlation of r (t) with s (t) yields:

the time delay tau of the ionosphere echo can be obtained by searching the extreme value of R (u)_i. So the ionosphere virtual height h ═ c τ_i/2. And respectively carrying out the processing on the echo signals with different frequencies to obtain an ionosphere echo spectrogram. According to the reflection trace in the ionosphere echo spectrum, the maximum electron concentration of each layer can be obtained, and the maximum plasma frequency corresponding to the layer is as follows:

however, only the ionospheric height information can be acquired by this method, and azimuth information and doppler information cannot be acquired in space. In the radar system, the adopted receiving antenna is an electric antenna, and a directional diagram of the electric antenna has null in the zenith direction and cannot receive an echo.

In order to solve the problem, the system is additionally provided with a group of devices for receiving ionospheric echoes, the devices form a 4 x 4 uniform antenna planar array by taking 16 magnetic antennas as array elements, the normalized gain of a directional pattern of the magnetic antennas in the zenith direction is 1, and the ionospheric echoes in the zenith direction can be received. And the area array antenna can perform two-dimensional beam forming in the horizontal and pitching directions, so that the position of the ionosphere can be further positioned on the basis of distance information. The spatial structure of the array elements is shown in fig. 5. The array element 1 is a reference phase reference point and is positioned at the origin position, and the whole planar array is positioned on the xoy plane. The working modes can be divided into two types:

mode 1, synchronous with offshore object detection. The local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system are set to be the same as the receiving local oscillation signal and the receiving frequency of the offshore target detection, and the time sequence is synchronous. The difference in the magnetic and electric antenna patterns results in an increase in the echo gain in the zenith or other high altitude directions. Ionospheric echoes are received more efficiently. The method for obtaining the range-doppler spectrum by signal processing is the same as that of the offshore target detection subsystem. In order to obtain the spatial orientation, 2-dimensional spatial beam forming is carried out on echo data from an ionosphere echo point. In the figure, the incoming wave direction is assumed to beWherein the content of the first and second substances,for pitch angle, θ ∈ [0,2 π ]]Is the pitch angle of the signal. Defining the position of array element as c_n＝(x_n,y_n) Unit vector of far field signal isThe phase difference of the array element n with respect to the origin of coordinates can be expressed as:

where λ is the electromagnetic wavelength. The steering vector of the planar array can be derived:

to pairWeight vector when directional incoming wave is used for beam forming ^*Indicating that conjugation was taken. According to the principle of pattern multiplication, the beamforming expression is:

wherein the content of the first and second substances,is the directional diagram of a single magnetic antenna array element.

The dimensionality reduction is performed here, taking into account the spatial complexity of the 2-dimensional beamforming. The E-plane pattern of the magnetic antenna is an "8" shape. For any one pitch angleThe horizontal angle of the pattern in the E plane is related to the horizontal angle. The H-plane directional pattern of the magnetic antenna is a circle, and the directional gain of the H-plane directional pattern is a circle with the normalized amplitude smaller than 1 for any horizontal angle theta', and is independent of the pitch angle. I.e. the pitch angle does not affect the beam forming result for the horizontal angle. This provides a theoretical basis for the dimension reduction treatment. Two beamforming results in the horizontal and elevation directions can then be obtained, respectively, to obtain two sets of bearing information. Calculating stepThe method comprises the following steps:

1. and calculating and obtaining parameters. The method comprises the following steps of selecting the spatial position of the array element of the magnetic antenna (selecting a reference antenna as a coordinate 0 point to perform two-dimensional uniform planar array arrangement to obtain the spatial position coordinate of the array element), and selecting parameters such as wavelength, pulse repetition period, transmission beam direction and the like according to a working mode, thereby facilitating subsequent calculation.

2. And performing signal processing such as pulse compression, coherent accumulation and the like on the echo data to obtain an RD spectrum. And selecting a target point from the RD spectrum to obtain target point data.

3. The echo data is copied in multiple copies. Because the E-plane directional pattern of the magnetic antenna is not an omnidirectional antenna directional pattern, when the horizontal projection direction of the true incoming wave direction deviates from the normal direction of the array element greatly (taking fig. 5 as an example, the θ direction in the figure is the projection angle of the incoming wave direction on the horizontal plane, and the X-axis positive direction is the normal direction at this time), the weighted value of the true incoming wave direction is not the maximum. Therefore, for such directional antennas, the beam forming must be limited to a certain spatial range to ensure the accuracy. The simulation experiment shows that the correct beam forming result can be ensured when the deviation of the normal direction is not more than +/-20 degrees. According to the direction of the transmitting beam, weighting vector angles are weighted by a plurality of angle values near the direction angle of the transmitting beam, and the weighted value of the real echo direction is ensured to be the maximum.

3. First, beam forming is performed in the horizontal direction. From the pitch angle without affecting the beam forming result of the horizontal angle, fixedTemporary fetchingThe E-plane pattern of the magnetic antenna is not an omni-directional pattern and needs to consider the directional function of the array elements. The normalized directivity shape function of the magnetic antenna isThe horizontal angle theta can be calculated by substituting the beam forming formula with the reference value₀The beamforming result of (1).

4. Making beam forming in the pitching direction to make theta equal to theta₀，θ₀＝θ₀. I.e. equivalent to multiplying the weight vector by a factor theta₀Resulting in a loss of weighting.The beam forming result in the elevation direction can be calculated.

And calculating to obtain beam forming results of a plurality of spatial angles according to the beam forming calculation method, and finally obtaining spectral data of distance-speed-spatial orientation three-dimensional information so as to complete positioning of the space position of the ionosphere.

And 2, synchronizing the mode 2 with the working mode of the plumb measuring instrument. At this time, the local oscillation signal, the receiving frequency and the receiving time sequence of the receiving system are set to be the same as the receiving local oscillation signal and the receiving frequency of the vertical measuring instrument, and the time sequence is synchronous. The receiving antenna of the vertical measuring instrument can only receive the ionosphere echo in the single direction of the zenith, and when the vertical measuring instrument works, the transmitted signal can leak in other directions. In conventional research, such leakage is often avoided in order to ensure energy concentration of the plumbing fixture in the zenith direction. When the receiving antenna array is added, the echoes of the transmitted signals in other directions can be received, so that the ionospheric echoes except the zenith direction can be received, and the ionospheric detection space range is expanded. The signal processing method is the same as that in mode 1, and will not be described here. Compared with the vertical measuring instrument, the vertical measuring instrument can additionally obtain spatial distribution information, Doppler information and the like in addition to the height (distance) information of an ionized layer.

The two working modes are controlled by parameters sent by the master control system to switch the working modes when the whole detection equipment is started.

Sometimes, in order to further acquire more accurate ionospheric spatial azimuth information, the conventional beamforming angle measurement is limited by the array aperture, so that the constraint brought by the array aperture needs to be broken through by means of a super-resolution method. For a 4 x 4 planar array, the two-dimensional MUSIC approach can be used. After more pulse compression and coherent accumulation data are acquired, each group selects a data point corresponding to an ionosphere echo to realize two-dimensional super resolution. The steering vector of the array is the same as the steering vector during beamforming, and is given by:

ionospheric echo signals are treated as far-field narrowband signals. Setting the ionosphere orientation in space toThe ionospheric echo is the aforementioned r (t). The amplitude of the echo received by the magnetic antenna is modulated by the direction diagram. The expression of the echo received by the nth array element is as follows:

where n (t) is 0-mean Gaussian white noise. K ionospheric echoes are observed in the RD spectrum in total with the azimuth ofThe received signal expression of the whole planar array is:

X(t)＝A(t)S(t)+N(t)

in the formula:

X(t)＝[x₁(t),x₂(t),...,x_N(t)]^T

accepting a data vector for the N dimension;

is a signal vector;

is a steering vector for the received data. N (t) is white Gaussian noise. And after constructing a receiving signal model with the array element antenna as the magnetic antenna, calculating according to a two-dimensional MUSIC algorithm. The method comprises the following steps:

1. calculating covariance matrix of received signal R (t) E (X (t)^T) And E represents expectation.

2. And (d) decomposing the characteristic values of the R (t), wherein the characteristic values are arranged from large to small, and the corresponding characteristic vectors are also arranged from large to small. Selecting a vector space formed by stretching the eigenvectors corresponding to the first k large eigenvalues as a signal subspace and recording the signal subspace as U_sThe rest of the feature vectors are noise subspaces and are marked as U_n。

3. From the orthogonality of the signal subspace and the noise subspace,at U_nShould be 0. In practice, due to the influence of noise, this expression should be a minimum. Thus solving forThe problem of (2) translates into the following mathematical problem:

4. taking the reciprocal of the above formula to obtain the productThe two-dimensional peak expression of (a):

and obtaining a super-resolution result through two-dimensional spectral peak search. In the specific calculation, in order to reduce the calculation amount, the data can be firstly subjected to beam forming to obtain the approximate spatial angle range of the ionized layer, and then the super-resolution processing is performed in the range, so that the search range can be reduced, and the calculation amount can be saved.

The time sequence control subsystem takes a time sequence controller as a core. The time sequence controller takes ARM and FPGA as main bodies, utilizes the GPIO interface of the FPGA to generate a plurality of paths of time sequence control signals which can be configured by software, and provides synchronous working time sequences and trigger signals for the antenna and the receiver switch controller respectively. The time sequence controller generates each path of time sequence signals through the FPGA after receiving time sequence parameters (such as trigger signals, pulse width of synchronous signals, opening and closing time length of a transmitter and the like) sent by the upper computer, and then is connected to each subsystem through a GPIO (general purpose input/output) interface of the response. And after each subsystem receives the corresponding analog control signal, starting a corresponding working mode.

The display control platform is connected with each part and each subsystem through the Ethernet and is responsible for functions of visualization of a control interface of the master control system, monitoring of equipment states, storage and display of detection results and the like. The detailed system architecture is given by fig. 6.

The key innovation point of the invention is also the technical effect that a receiving system control method and a signal processing method of the ocean information-ionosphere integrated detection system are designed. The ionosphere vertical measurement and the ocean information are synchronously obtained by combining the special characteristics of the magnetic antenna, the mutual interference between the ionosphere vertical measurement and the ocean information is avoided, and the distance, Doppler frequency and space distribution condition of the ionosphere can be obtained in real time.

The ionosphere verticality measuring instrument is combined with the high-frequency ground wave radar and the magnetic antenna array, so that the ionosphere information and the ocean information can be synchronously acquired. One is that the receiving system is synchronous with the original radar and the original vertical measuring instrument through a system time sequence control method without mutual interference, and the ability of acquiring the ionosphere information in real time is increased from the aspect of time. And secondly, aiming at the characteristic that the space directional diagram of the magnetic antenna is different from that of the omnidirectional antenna, the 2-dimensional beam forming method adopting the dimension reduction processing can save the computing capability on the premise of ensuring the measurement precision, and the super-resolution processing method is added to more finely acquire the space direction.

Demonstration part (/ experiment/simulation// positive experimental data capable of demonstrating the inventive aspects of the invention, etc.)

The rationality of this scheme is verified by a set of results of signal processing. And (3) giving an RD spectrogram, wherein a horizontal angle, namely a pitch angle beam forming result and a two-dimensional super-resolution result are respectively shown in the figures 6-9. Two ionospheric echoes are set in the simulation, the radial distances to the radar are 50km and 150km respectively, and the corresponding Doppler frequency shifts are 2Hz and 0Hz respectively. (in the RD spectrum, Doppler shift corresponds to velocity information, and 2Hz is converted to 150 km/s). One of the points is taken as beam forming and super resolution, the horizontal angle is 10 degrees, and the azimuth angle is 15 degrees. The radar has the working frequency of 2MHz, adopts a pulse system, has the pulse width of 8us and the pulse repetition period of 4 ms. The echo signal-to-noise ratio is set to 0db, and 512 pulses are taken for processing. The 4 x 4 uniform planar array element spacing is half a wavelength and the reference array element arrangement is as shown in figure 5. The signal-to-noise ratio of the super-resolution algorithm is set to be 20db (because the super-resolution algorithm takes an echo point in the RD spectrum as a snapshot data point for processing, the signal-to-noise ratio is improved during the RD spectrum processing, the signal-to-noise ratio is reasonably set), and the number of the snapshots is 1024.

In the simulation process of the system signal processing, the RD spectrum simulates echoes of two small ionized layers in space. The location of the ionosphere and the doppler frequency parameters of the echoes are selected to approximate the parameters observed in previous experiments. The parameter setting of the radar in the simulation is the same as the actual parameter setting principle. As can be seen from the RD spectrum of FIG. 6, after the matched filtering and pulse compression processing, the velocity (Doppler) information and distance information corresponding to the target can be displayed, that is, the target with a Doppler frequency of 2Hz at a distance of 50km corresponds to the target point with a velocity of 150m/s at a distance of 50km in the RD spectrum, and the target with a Doppler frequency of 0Hz at a distance of 150km corresponds to the target point with a velocity of 0m/s at a distance of 150km in the RD spectrum, and the signal-to-noise ratio is effectively improved. The next step is to obtain two-dimensional orientation information. Coarse resolution is first performed by beamforming. According to the two-dimensional beam forming processing method for reducing the dimension, the obtained beam forming processing results in the horizontal direction and the pitching direction are respectively 10 degrees and 15 degrees and are consistent with preset parameters, and the effectiveness of the method is verified by a simulation result. And then, fine resolution is carried out by adopting a two-dimensional super-resolution method. In the processing result of the 2D-MUSIC, the yellow position in the graph is the target angle obtained by super resolution, and it can be seen that the angle information obtained by super resolution is consistent with the preset parameters and is more accurate compared with beam forming. Limited by computer performance, the velocity (doppler) and range resolution performance in RD spectra in simulations is not optimal. The practical system adopts a high-performance computer, can process more pulses and improves the resolution capability.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When used in whole or in part, can be implemented in a computer program product that includes one or more computer instructions. When loaded or executed on a computer, cause the flow or functions according to embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions may be transmitted from one website site, computer, server, or data center to another website site, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL), or wireless (e.g., infrared, wireless, microwave, etc.)). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that includes one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.