Method and device for separating ionospheric O-waves and X-waves

Abstract

The present invention provides a method and device for separating ionospheric O waves and X waves, and the method comprises: obtaining signal echo data of the ionosphere at multiple times within 24 hours, and preprocessing the signal echo data at each time to obtain a frequency-height diagram at each time; determining the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency-height diagram at each time according to the tracing branches of the O waves and X waves in the F2 layer of the frequency-height diagram at each time, and fitting to obtain a phase compensation function and an amplitude compensation function; separating the O waves and X waves in the frequency-height diagram at multiple times based on the phase compensation function and the amplitude compensation function. The present invention obtains the phase compensation function and the amplitude compensation function through the tracing branches of the O waves and X waves in the F2 layer, and substitutes them into the original data to realize the separation and extraction of the O waves and the X waves, so that the separated results are still saved in the form of original data, which is convenient for storing the separation results and also convenient for further processing of the separated original data.

Description

Technical Field

[0001] The present invention relates to the technical field of ionospheric detection, and in particular to a method and a device for separating ionospheric O-waves and X-waves. Background Art

[0002] The ionospheric altimeter utilizes the characteristic of reflection when the signal collides with the same-frequency ion group in the air. When detecting the ionosphere, the altimeter transmitter located on the ground transmits a sweep signal and starts timing. The receiving end located on the ground waits to receive the echo signal and records the time scale when the echo signal arrives completely. Different sweep frequencies will result in different time scales. Combined with the propagation speed of electromagnetic waves in a vacuum, the virtual height of the ionosphere corresponding to different sweep frequency points can be obtained. After receiving a series of sweep electromagnetic waves, a two-dimensional image with the echo frequency on the x-axis and the virtual height of the ionosphere on the y-axis can be obtained, which is called a frequency-height map. Various information and parameters of the ionosphere can be obtained by analyzing and inverting the frequency-height map.

[0003] According to the propagation theory of electromagnetic waves in plasma, during the propagation of electromagnetic waves in the ionosphere, under the action of electric and magnetic fields, two elliptically polarized wave components with perpendicular principal axes and opposite rotation directions, namely O waves and X waves, will be differentiated. The two waves will experience attenuation and be incident on the receiver in pairs. Both will appear at the same time in the detection receiving window period of the ionospheric altimeter, resulting in two traces on the frequency-height diagram. When interpreting the parameters of the ionospheric frequency-height diagram, the two traces that appear at the same time will greatly affect the accuracy of the parameter interpretation, thereby reducing the accuracy of the frequency-height diagram inversion.

[0004] At present, the main methods for separating O-wave and X-wave in ionospheric high-frequency images are the traditional phase-shift cancellation method and image processing method. The traditional phase-shift cancellation method mainly uses the propagation characteristics of O-wave and X-wave to achieve phase addition and subtraction after phase shift to eliminate O-wave or X-wave, which is often achieved by using dual-channel orthogonal antennas and hardware phase shifters; the image processing method mainly uses deep neural networks to extract O-wave or X-wave traces. The dilemma faced by the traditional phase-shift cancellation method is that when using hardware phase shifters for phase shifting, the actual phase shift requirements of different frequency points are not the same, and the actual phase shift requirements of the overall detection system will change with the changes in time and space, and the elimination effect obtained by using a fixed phase shift value is not ideal; the dilemma faced by the image processing method combined with deep neural networks is that a large number of labeled training samples are required, and it takes a long time to adjust the parameters and retrain each time, and image processing can only process the traces on the image, and cannot actually eliminate the O-wave or X-wave components in the original data. Summary of the invention

[0005] The present invention provides a method and device for separating ionospheric O-waves and X-waves, so as to solve the defect of unsatisfactory separation effect of O-waves and X-waves in the prior art, and realize a convenient and accurate method for separating ionospheric O-waves and X-waves.

[0006] The present invention provides a method for separating ionospheric O-waves and X-waves, comprising:

[0007] Acquire signal echo data of the ionosphere at multiple times within 24 hours, and pre-process the signal echo data at each time to obtain a frequency-height diagram at each time;

[0008] Determine the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment;

[0009] A phase compensation function and an amplitude compensation function are obtained by fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height graph at each moment;

[0010] The O wave and the X wave in the frequency-height diagram at multiple moments are separated based on the phase compensation function and the amplitude compensation function.

[0011] According to a method for separating ionospheric O waves and X waves provided by the present invention, before the step of determining the phase compensation parameter and the amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O waves and the X waves in the F2 layer of the frequency height diagram at each moment, the method further comprises:

[0012] Traversing the peak value of each frequency point in the frequency-height graph at each moment from high to low, and determining a double bifurcation portion where two peak values ​​appear simultaneously;

[0013] determining a point at a higher range gate position in the double bifurcation portion as an O-wave trace, and determining a point at a lower range gate position as an X-wave trace;

[0014] The trace branches of the O wave and the X wave in the F2 layer are determined according to the O wave trace and the X wave trace.

[0015] According to a method for separating ionospheric O waves and X waves provided by the present invention, the step of determining the phase compensation parameter and the amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O waves and the X waves in the F2 layer of the frequency height diagram at each moment specifically comprises:

[0016] In the case where both the O-wave trace and the X-wave trace exist at the frequency point, the amplitude and the phase shift when the difference between two peak points in the data sequence of the frequency point is maximized are determined as the phase compensation parameter and the amplitude compensation parameter;

[0017] In the case that only O-wave traces or X-wave traces exist at the frequency point, the phase compensation parameter and the amplitude compensation parameter of the frequency point are determined according to the type of traces to be separated.

[0018] According to a method for separating ionospheric O waves and X waves provided by the present invention, before the step of fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment to obtain a phase compensation function and an amplitude compensation function, the method further includes:

[0019] The O wave and the X wave in the F2 layer of the frequency height diagram at each moment are eliminated and separated based on the phase compensation parameter and the amplitude compensation parameter.

[0020] According to a method for separating ionospheric O waves and X waves provided by the present invention, after the step of eliminating and separating the O waves and X waves in the F2 layer of the frequency height diagram at each moment based on the phase compensation parameter and the amplitude compensation parameter, the method further comprises:

[0021] The separation effect of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment is observed, and when the separation effect does not meet the preset separation condition, a low confidence value is set for the phase compensation parameter and the amplitude compensation parameter.

[0022] According to a method for separating ionospheric O waves and X waves provided by the present invention, the step of fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment to obtain a phase compensation function and an amplitude compensation function specifically comprises:

[0023] The phase compensation parameter and the amplitude compensation parameter corresponding to the frequency height diagram at each moment are unwound and clustered, and the phase compensation function and the amplitude compensation function are obtained by fitting.

[0024] The present invention also provides a device for separating ionospheric O-waves and X-waves, comprising:

[0025] An acquisition module is used to acquire signal echo data of the ionosphere at multiple times within 24 hours, and pre-process the signal echo data at each time to obtain a frequency-height diagram at each time;

[0026] A determination module, for determining a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment;

[0027] A fitting module, used for fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment to obtain a phase compensation function and an amplitude compensation function;

[0028] A separation module is used to separate O waves and X waves in the frequency-height diagrams at multiple moments based on the phase compensation function and the amplitude compensation function.

[0029] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for separating ionospheric O-waves and X-waves as described in any one of the above is implemented.

[0030] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for separating ionospheric O-waves and X-waves as described in any one of the above is implemented.

[0031] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the method for separating ionospheric O-waves and X-waves as described in any one of the above is implemented.

[0032] The method and device for separating ionospheric O-waves and X-waves provided by the present invention obtain a phase compensation function and an amplitude compensation function through the tracing branches of the F2 layer O-waves and X-waves, and substitute the phase compensation function into the original data to realize the separation and extraction of the O-waves and X-waves, so that the separated results are still stored in the form of original data, which is convenient for storing the separation results and further processing the separated original data, and can avoid the interference caused by the simultaneous existence of O-waves and X-waves when the original data is used for direction finding. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a schematic flow chart of the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0035] Figure 2 It is a schematic diagram for displaying a frequency-height diagram in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0036] Figure 3 It is a phase compensation parameter diagram for displaying multiple moments in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0037] Figure 4 It is a phase compensation parameter diagram for displaying multiple moments after unwinding in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0038] Figure 5 It is a schematic diagram for showing a phase compensation function in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0039] Figure 6 It is a schematic diagram for showing a frequency-height diagram for eliminating X-waves in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0040] Figure 7 It is a phase compensation parameter diagram corresponding to multiple moments in a case of eliminating O waves in the method for separating ionospheric O waves and X waves provided by the present invention;

[0041] Figure 8 It is a phase compensation parameter diagram at multiple moments after unwinding corresponding to a case of eliminating O waves in the method for separating ionospheric O waves and X waves provided by the present invention;

[0042] Fig. 9 It is a schematic diagram of a phase compensation function corresponding to a case of eliminating O waves in the method for separating ionospheric O waves and X waves provided by the present invention;

[0043] Fig.10 It is a schematic diagram of a frequency-height diagram of case 1 in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0044] Fig.11 It is a schematic diagram of the OX separation after the separation in the case 1 of the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0045] Fig.12 It is a schematic diagram of a frequency-height diagram of case 2 in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0046] Fig.13 It is a schematic diagram of the OX separation after the separation in Case 2 of the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0047] Fig.14 It is a frequency-height diagram schematic diagram of case 3 in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0048] Fig.15 It is a schematic diagram of the OX separation after the case 3 in the method for separating ionospheric O-waves and X-waves provided by the present invention;

[0049] Fig.16 It is a schematic structural diagram of the device for separating ionospheric O-waves and X-waves provided by the present invention;

[0050] Fig.17 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Combine the following Figures 1 to 15 The present invention introduces the separation method of ionospheric O-wave and X-wave, as shown in FIG. Figure 1 As shown, the method includes:

[0053] Step 101, acquiring signal echo data of the ionosphere at multiple times within 24 hours, and preprocessing the signal echo data at each time to obtain a frequency-height diagram at each time;

[0054] Based on the ionospheric altimeter and the dual dipole antenna, the signal echo data of the ionosphere at multiple times within 24 hours are obtained. Among them, 24 hours refers to 24 hours from any time.

[0055] Specifically, the detection mode of the ionospheric altimeter is set to the sweep detection mode, and its coding mode, start and end frequency points, frequency step, transmission duty cycle, number of sweep single-point detections and other parameters are set, and the frequency group detection time is calculated. Among them, the detection blind area caused by the length of the code sequence for coding and modulating the signal should be lower than the lower limit of the target detection range, and the maximum detection distance should be sufficient to cover the entire target detection range.

[0056] Among them, appropriately increasing the number of detections of a single frequency point is helpful to obtain a more obvious echo, but too many times are not conducive to eliminating O waves or X waves. Generally, 8 to 16 times are sufficient.

[0057] In a feasible implementation manner, the detection blind area caused by the length of the code sequence used to encode and modulate the signal is less than 60 km, and the maximum detection distance determined by the transmission duty cycle and the signal coding length is greater than 300 km.

[0058] The signal echo data at multiple different times within 24 hours are received by two dipole antennas with phase difference. After preprocessing the acquired dual-channel signal echo data, the signal echo data at each time is sorted into a frequency-height map matrix, and nonlinear energy clustering is performed on it to suppress background noise, clutter and interference, and then it is processed into the form of a frequency-height map, such as Figure 2 shown.

[0059] There is no strict orthogonal requirement for the placement angles of the dual dipole antennas. They can be placed in an interlaced manner in an area where sky wave echo signals can be received.

[0060] It should be noted that after summing up the results obtained from multiple detections of each frequency point, the phase information must be retained, and the summation result is used as the final phase result of the frequency point.

[0061] In a specific implementation, a threshold is designed for the frequency-height map matrix based on the peak energy minus 5 dBm, and a sigmoid nonlinear function is used to suppress background noise, clutter and interference to achieve nonlinear energy clustering, that is, frequency points whose energy difference with the peak point is within 5 dBm are retained in the frequency-height map matrix, and the retained frequency points are processed into the form of a frequency-height map.

[0062] Step 102, determining a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment;

[0063] It should be noted that the frequency-height diagram obtained at each moment contains the frequency points corresponding to the F1 layer and the F2 layer in the ionosphere. The present application realizes the separation of the O-wave and X-wave of the entire ionosphere by tracing the tracing branches of the O-wave and the X-wave corresponding to the F2 layer.

[0064] Specifically, it is difficult to automatically batch identify the echo tracings below the F2 layer, and the echo phase difference between the dual channels at the same frequency point is not easy to change with time. At the same time, the echo tracings of the F2 layer have the characteristics of diurnal variation, that is, the tracings at high frequency points during the day will fall back to low frequency points at night. Therefore, by utilizing the diurnal variation characteristics of the ionosphere, more accurate phase shift and amplitude parameters can be iteratively obtained based on the tracing branches of the F2 layer O waves and X waves, that is, the phase compensation parameters and amplitude compensation parameters of each frequency point in the frequency-height diagram at each moment, which are used to separate the ionospheric O waves and X waves.

[0065] Specifically, for the frequency-height graph corresponding to the signal echo data at different times within 24 hours, the O-wave and X-wave tracing branches of the F2 layer are automatically distinguished, and the O-wave and X-wave tracing branches of the F2 layer of the frequency-height graph at each time are obtained. It should be noted that the collection of F2 layer tracing branches at each time should cover the entire detection frequency band as much as possible.

[0066] Step 103, obtaining a phase compensation function and an amplitude compensation function by fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height graph at each moment;

[0067] For the frequency-height graph at each moment within 24 hours, determine the tracing branches of the O wave and the X wave of the F2 layer in each frequency-height graph, and obtain the phase compensation parameters and amplitude compensation parameters of each frequency point in each frequency-height graph based on the tracing branches of the O wave and the X wave of the F2 layer, and obtain the frequency-phase parameter graph at different moments within 24 hours, such as Figure 3As shown; the phase compensation parameters are unwrapped and clustered, as shown Figure 4 As shown, finally, the clustered phase compensation parameters are fitted to obtain the phase compensation function, as shown in Figure 5 shown.

[0068] Optionally, the method of obtaining the amplitude compensation function is similar to the method of obtaining the phase compensation function, and thus will not be described in detail.

[0069] In another feasible implementation, since the result of the amplitude compensation parameter is usually relatively fixed, compensation may be performed directly in the frequency-height graph based on the determined amplitude compensation parameter.

[0070] Step 104 : Separate the O wave and the X wave in the frequency-height diagram at multiple moments based on the phase compensation function and the amplitude compensation function.

[0071] Substituting the fitted phase compensation function and amplitude compensation function into the original data, we can obtain the frequency-height diagram with X-wave removed and the frequency-height diagram with O-wave eliminated, respectively. The original data is the data received by the double dipole antenna.

[0072] The present invention obtains a phase compensation function and an amplitude compensation function through the tracing branches of the O-wave and the X-wave of the F2 layer, and substitutes the phase compensation function into the original data to realize the separation and extraction of the O-wave and the X-wave, so that the separated results are still stored in the form of original data, which is convenient for storing the separation results and further processing the separated original data, and can avoid the interference caused by the simultaneous existence of the O-wave and the X-wave when the original data is used for direction finding.

[0073] In addition, it should be noted that the separation methods of O-wave and X-wave in ionospheric high-frequency images are mainly traditional phase shift cancellation method and image processing method. Among them, the traditional phase shift cancellation method mainly uses the propagation characteristics of O-wave and X-wave to achieve phase addition and subtraction after phase shift to eliminate O-wave or X-wave, which is often achieved by using dual-channel orthogonal antennas and hardware phase shifters.

[0074] When using a hardware phase shifter to shift phase, the actual phase shift requirements of different frequency points are not the same, and with the change of time and space, the actual phase shift requirements of the overall detection system will change. The elimination effect obtained by using a fixed phase shift value is not ideal. Therefore, the use of traditional phase shift cancellation method requires high accuracy of hardware equipment.

[0075] The present application realizes the separation of O-wave and X-wave by substituting the phase compensation function and amplitude compensation function obtained based on the O-wave and X-wave tracing of the F2 layer into the original data. Self-calibration can be achieved based on the data of the two receiving channels. On the one hand, O-wave and X-wave separation can be achieved by using a portable dual-dipole antenna without the need for additional hardware equipment. On the other hand, self-calibration can be achieved based on the data of the two receiving channels without the need for additional in-machine calibration and open-loop calibration. There is no need to change the original detection timing, process and signal processing method of the ionospheric altimeter. The application has extremely strong versatility and greatly reduces the requirements for hardware equipment.

[0076] Furthermore, the image processing method is to use deep neural networks to extract O-wave or X-wave tracings. This method requires a large number of labeled training samples when training the neural network. It takes a long time to adjust the parameters and retrain each time. In addition, image processing can only process the tracings on the image and cannot actually eliminate the O-wave or X-wave components in the original data.

[0077] The present application realizes the separation of O-wave and X-wave by substituting the acquired phase compensation function and amplitude compensation function into the original data, thereby eliminating the components of O-wave and X-wave in the original data, which is conducive to further application of the separated original data.

[0078] In the method for separating ionospheric O waves and X waves of the present invention, before the step of determining the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O waves and X waves in the F2 layer of the frequency height diagram at each moment, the method further includes:

[0079] Traversing the peak value of each frequency point in the frequency-height graph at each moment from high to low, and determining a double bifurcation portion where two peak values ​​appear simultaneously;

[0080] determining a point at a higher range gate position in the double bifurcation portion as an O-wave trace, and determining a point at a lower range gate position as an X-wave trace;

[0081] The trace branches of the O wave and the X wave in the F2 layer are determined according to the O wave trace and the X wave trace.

[0082] First, for each moment of the frequency-height diagram, the virtual height range of the target trace is set to 130 km to 450 km to reduce the interference of ground waves, two-hop or multi-hop echoes, and on this basis, the trace branch of the F2 layer in the frequency-height diagram is obtained. The virtual height range of the target trace is obtained according to the highest position of the one-hop ionospheric detection echo of the empirical model.

[0083] Furthermore, for the extraction of the O-wave and X-wave tracing branches of the F2 layer in the frequency-height map, as shown in Figure 2As shown, the peak values ​​of each frequency point are traversed from the high frequency point to the low frequency point, and the double bifurcation part where two peak points appear at the same time is distinguished.

[0084] For the bifurcation portion, the trace at the higher range gate position is determined as the O-wave trace, and the trace at the lower range gate position is determined as the X-wave trace. Figure 6 As shown, Figure 6 The continuous red frequency points are the X-wave traces.

[0085] It should be noted that there is no O wave at the higher frequency at the end of the bifurcation, only X wave, and the only peak point of this frequency point is taken as the X wave trace.

[0086] The O-wave trace and X-wave trace of the F2 layer in the frequency-height diagram at each moment are extracted in the above-mentioned manner.

[0087] In the method for separating ionospheric O waves and X waves of the present invention, the step of determining the phase compensation parameter and the amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O waves and the X waves in the F2 layer of the frequency height diagram at each moment specifically comprises:

[0088] In the case where both the O-wave trace and the X-wave trace exist at the frequency point, the amplitude and the phase shift when the difference between two peak points in the data sequence of the frequency point is maximized are determined as the phase compensation parameter and the amplitude compensation parameter;

[0089] Specifically, when separating the O-wave and X-wave traces of the F2 layer in the frequency-height diagram, a set of orthogonal dipole antennas is set up. , the signals received by the two antennas are and According to the propagation properties of O-waves and X-waves, under ideal conditions, O-waves and X-waves can be regarded as two circularly polarized waves with opposite rotation directions. and According to the propagation characteristics, the phase shift of antenna a is -90° and 90° respectively. and Antenna signal with b Adding together we get the O wave and the X wave, as shown below:

[0090] ;

[0091] ;

[0092] However, in actual situations, the phase difference between the two channels will not be exactly 90°, and due to the interference of the external environment and the characteristics of the internal circuit, the actual phase shift at each frequency point is different and the amplitude is inconsistent. Therefore, when applying this method, it is necessary to change the phase shift and amplitude of each frequency point according to the actual situation. After optimization, the O wave and X wave are as follows:

[0093] ;

[0094] ;

[0095] In the formula, α represents the amplitude, represents phase shift, and the subscript represents the number of channels.

[0096] When O-wave and X-wave traces exist at the same frequency, there are two peak points in the data sequence of the corresponding frequency. and When , a method for iterative optimization of phase shift and amplitude can be proposed: Assuming that the electromagnetic wave amplitude and phase shift are and , the target sequence is y, and the independent variable sequence is x, then the optimization problem is transformed into facing sequence, if the sequence of the corresponding frequency points on the coherent accumulation matrix is ​​changed and It reaches the maximum, that is, the difference between the two peak points in the data sequence of the corresponding frequency point is maximized.

[0097] To this end, further simplify it to: The corresponding frequency sequence of its own coherent accumulation matrix and The amplitude and phase shift values ​​are iterated as shown below:

[0098] ;

[0099] Where A and B are the correlation matrices of the two channels a and b respectively, i is the corresponding frequency point, and the two peak points are and Represents the respective positions of the O wave and the X wave at the frequency point. Substituting the predetermined positions of the O wave and the X wave into the above formula, it is easy to know that the corresponding optimal iterative phase shift is consistent under different amplitudes. Therefore, the method of first assuming that the amplitude is a fixed iterative phase shift and then performing amplitude iteration on the basis of the optimal iterative phase shift is adopted to obtain the optimal phase shift and amplitude of the current frequency point as the phase compensation parameter and amplitude compensation parameter.

[0100] In the case that only O-wave traces or X-wave traces exist at the frequency point, the phase compensation parameter and the amplitude compensation parameter of the frequency point are determined according to the type of traces to be separated.

[0101] At a certain frequency point, there is only one O wave or X wave trace, that is, there is only one peak point in the data sequence of the corresponding frequency point. In the case of , the iteration goal is to strengthen or weaken the extreme point according to whether the target to be eliminated is X wave or O wave, that is, according to the tracing category.

[0102] The same method of completing phase shift iteration and then performing amplitude iteration is used to obtain the optimal phase shift and amplitude compensation for the current frequency point, as shown in the following formula:

[0103] ;

[0104] Thus, the phase compensation parameters and amplitude compensation parameters in this case are obtained.

[0105] It should be noted that, for the above-mentioned method of iteratively acquiring phase compensation parameters and amplitude compensation parameters, the iteration range of the amplitude compensation parameter should not be set too large, so as to avoid increasing the interference of bad detection points on the amplitude compensation parameter as much as possible.

[0106] In the method for separating ionospheric O waves and X waves of the present invention, before the step of fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment to obtain the phase compensation function and the amplitude compensation function, the method further includes:

[0107] The O wave and the X wave in the F2 layer of the frequency height diagram at each moment are eliminated and separated based on the phase compensation parameter and the amplitude compensation parameter.

[0108] The phase compensation parameters and amplitude compensation parameters obtained after the optimization iteration are substituted into the original data, and two new frequency-height maps are drawn to eliminate the O-wave and X-wave of the F2 layer tracing branch respectively. On the basis of the frequency-height map with the O-wave eliminated, a notch filter is made on the frequency-height map with the X-wave eliminated, and the O-wave energy and the X-wave energy are corresponded to the maximum and minimum values ​​of the image energy to achieve the separation of the O-wave and the X-wave, thereby achieving the separation of the O-wave and the X-wave of the F2 layer on each frequency-height map.

[0109] In the method for separating ionospheric O waves and X waves of the present invention, after the step of eliminating and separating the O waves and X waves in the F2 layer of the frequency height diagram at each moment based on the phase compensation parameter and the amplitude compensation parameter, the method further includes:

[0110] The separation effect of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment is observed, and when the separation effect does not meet the preset separation condition, a low confidence value is set for the phase compensation parameter and the amplitude compensation parameter.

[0111] For each frequency height graph in which the O wave and the X wave are eliminated, the separation effect of the O wave and the X wave of the F2 layer tracing branch is observed. When the separation effect does not meet the preset separation conditions, that is, when the separation effect is poor, the confidence value of the used parameters can be manually set according to the separation effect, and a low confidence value can be set for the parameters with poor separation effect.

[0112] Optionally, the preset separation condition is determined empirically.

[0113] When fewer frequency-height graphs are obtained, setting a low confidence value is of great help to the subsequent parameter fitting. If more frequency-height graphs are obtained, the confidence value method can be omitted. Based on the statistical characteristics, Gaussian function fitting can be used to obtain better fitting results and the best iterative parameters for each frequency point.

[0114] In the method for separating ionospheric O waves and X waves of the present invention, the step of fitting the phase compensation function and the amplitude compensation function according to the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment specifically includes:

[0115] The phase compensation parameter and the amplitude compensation parameter corresponding to the frequency height diagram at each moment are unwound and clustered, and the phase compensation function and the amplitude compensation function are obtained by fitting.

[0116] For each frequency-height graph acquired within 24 hours, after obtaining its phase compensation parameters and amplitude compensation parameters in the above manner, the phase compensation parameters are unwrapped and clustered to remove free points. When the number of parameter groups is small, the average of each frequency point is taken and a polynomial curve is fitted. The frequency-phase shift fitting function covering the entire frequency band is extended at both ends of the curve to obtain a phase compensation function. When obtaining the frequency-amplitude compensation function, that is, the amplitude compensation function, unwrapping is not required.

[0117] This process will obtain the frequency-phase shift fitting function for eliminating X waves, the frequency-phase shift fitting function for eliminating O waves, and the frequency-amplitude compensation function.

[0118] Furthermore, the obtained phase compensation function and amplitude compensation function are substituted into the original data to obtain the frequency-height map with X-wave eliminated and the frequency-height map with O-wave eliminated, respectively. On the basis of the frequency-height map with O-wave eliminated, a notch filter is performed on the frequency-height map with X-wave eliminated, and the O-wave energy and the X-wave energy are corresponded to the maximum and minimum values ​​of the image energy, thereby realizing the separation of O-wave and X-wave.

[0119] It should be noted that when using a notch filter to reconstruct the O-wave and X-wave dual-mode frequency-height map, the background noise needs to be suppressed to the middle value of the O-wave energy and the X-wave energy, so as to clearly display the separated results. At the same time, the iteratively obtained amplitude compensation function only plays a role in further strengthening the weakening effect to counter various interferences in the environment and possible distortion of polarized waves.

[0120] Since the echo tracing of the F2 layer has the characteristic of diurnal variation, the phase compensation function and frequency compensation function obtained in the present application are stable over a long period of time, and can stably separate the O wave and X wave of the detection data within a week, that is, the tracing extraction of the O wave or X wave can be completed without re-obtaining new parameters.

[0121] In a specific implementation method of eliminating the X-wave trace branch of the F2 layer, the detection data at 12:00 on May 22, 2024 is taken and sorted into a frequency-height diagram. The peak values ​​of each frequency point are traversed from the high frequency point to the low frequency point, and the double bifurcation part where two peak points appear at the same time is distinguished, and the trace branches of the X-wave and O-wave of the F2 layer are determined. The original frequency-height diagram sorted according to the detection data is as follows: Figure 2 As shown, the frequency diagram of the separated X wave is as follows Figure 6 shown.

[0122] In a specific implementation of phase calibration for eliminating X-waves, 7 sets of detection data on May 22, 2024 are uniformly taken to search for the best phase for eliminating X-waves at each time point, such as Figure 3 As shown, after phase unwrapping, Figure 4 As shown, the best phase compensation function for eliminating X waves is Figure 5 shown.

[0123] In a specific implementation of phase calibration for eliminating O waves, 7 sets of detection data on May 22, 2024 are uniformly taken to search for the best phase for eliminating O at each time point, such as Figure 7 As shown, after phase unwrapping, Figure 8 As shown, the best phase compensation function for eliminating O wave is obtained, such as Fig. 9 shown.

[0124] In a specific frequency sweep observation implementation, as case 1, the phase amplitude parameters obtained on May 22, 2024 are used to separate the O wave and X wave of the detection data at 8:30 on May 24, 2024. The 16-bit complementary code with a period of 1.6384ms and a duty cycle of 5% is set for frequency sweep detection, so that the detection blind area caused by the code sequence length of the signal coding modulation is less than 60km and the maximum detection distance is greater than 300km. The original frequency height diagram obtained is as follows: Fig.10 As shown, the frequency height diagram obtained after separating the O wave and the X wave is as follows Fig.11 shown.

[0125] In a specific frequency sweep observation implementation, as case 2, the phase amplitude parameters obtained on May 22, 2024 are used to separate the O wave and X wave of the detection data at 10:32 on May 27, 2024. The 16-bit complementary code with a period of 1.6384ms and a duty cycle of 5% is set for frequency sweep detection, so that the detection blind area caused by the code sequence length of the signal coding modulation is less than 60km and the maximum detection distance is greater than 300km. The original frequency height diagram obtained is as follows: Fig.12 As shown, the frequency height diagram obtained after separating the O wave and the X wave is as follows Fig.13 shown.

[0126] In a specific frequency sweep observation implementation, as case 3, the phase amplitude parameters obtained on May 22, 2024 are used to separate the O wave and X wave of the detection data at 16:00 on May 29, 2024. The 16-bit complementary code with a period of 1.6384ms and a duty cycle of 5% is set for frequency sweep detection, so that the detection blind area caused by the code sequence length of the signal coding modulation is less than 60km and the maximum detection distance is greater than 300km. The original frequency height diagram obtained is as follows Fig.14 As shown, the frequency height diagram obtained after separating the O wave and the X wave is as follows Fig.15 shown.

[0127] The following is a description of the ionospheric O-wave and X-wave separation device provided by the present invention. The ionospheric O-wave and X-wave separation device described below and the ionospheric O-wave and X-wave separation method described above can be referred to each other.

[0128] like Fig.16 As shown, the ionospheric O-wave and X-wave separation device includes an acquisition module 1601, a determination module 1602, a fitting module 1603 and a separation module 1604:

[0129] The acquisition module 1601 is used to acquire the signal echo data of the ionosphere at multiple times within 24 hours, and pre-process the signal echo data at each time to obtain the frequency-height diagram at each time;

[0130] Based on the ionospheric altimeter and the dual dipole antenna, the signal echo data of the ionosphere at multiple times within 24 hours are obtained. Among them, 24 hours refers to 24 hours from any time.

[0131] Specifically, the detection mode of the ionospheric altimeter is set to the sweep detection mode, and its coding mode, start and end frequency points, frequency step, transmission duty cycle, number of sweep single-point detections and other parameters are set, and the frequency group detection time is calculated. Among them, the detection blind area caused by the length of the code sequence for coding and modulating the signal should be lower than the lower limit of the target detection range, and the maximum detection distance should be sufficient to cover the entire target detection range.

[0132] Among them, appropriately increasing the number of detections of a single frequency point is helpful to obtain a more obvious echo, but too many times are not conducive to eliminating O waves or X waves. Generally, 8 to 16 times are sufficient.

[0133] In a feasible implementation manner, the detection blind area caused by the length of the code sequence used to encode and modulate the signal is less than 60 km, and the maximum detection distance determined by the transmission duty cycle and the signal coding length is greater than 300 km.

[0134] The signal echo data at multiple different times within 24 hours are received by two dipole antennas with phase difference. After preprocessing the acquired dual-channel signal echo data, the signal echo data at each time is sorted into a frequency-height map matrix, and nonlinear energy clustering is performed on it to suppress background noise, clutter and interference, and then it is processed into the form of a frequency-height map, such as Figure 2 shown.

[0135] There is no strict orthogonal requirement for the placement angles of the dual dipole antennas. They can be placed in an interlaced manner in an area where sky wave echo signals can be received.

[0136] It should be noted that after summing up the results obtained from multiple detections of each frequency point, the phase information must be retained, and the summation result is used as the final phase result of the frequency point.

[0137] In a specific implementation, a threshold is designed for the frequency-height map matrix based on the peak energy minus 5 dBm, and a sigmoid nonlinear function is used to suppress background noise, clutter and interference to achieve nonlinear energy clustering, that is, frequency points whose energy difference with the peak point is within 5 dBm are retained in the frequency-height map matrix, and the retained frequency points are processed into the form of a frequency-height map.

[0138] A determination module 1602 is used to determine a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment;

[0139] It should be noted that the frequency-height diagram obtained at each moment contains the frequency points corresponding to the F1 layer and the F2 layer in the ionosphere. The present application realizes the separation of the O-wave and X-wave of the entire ionosphere by tracing the tracing branches of the O-wave and the X-wave corresponding to the F2 layer.

[0140] Specifically, it is difficult to automatically batch identify the echo tracings below the F2 layer, and the echo phase difference between the dual channels at the same frequency point is not easy to change with time. At the same time, the echo tracings of the F2 layer have the characteristics of diurnal variation, that is, the tracings at high frequency points during the day will fall back to low frequency points at night. Therefore, by utilizing the diurnal variation characteristics of the ionosphere, more accurate phase shift and amplitude parameters can be iteratively obtained based on the tracing branches of the F2 layer O waves and X waves, that is, the phase compensation parameters and amplitude compensation parameters of each frequency point in the frequency-height diagram at each moment, which are used to separate the ionospheric O waves and X waves.

[0141] Specifically, for the frequency-height graph corresponding to the signal echo data at different times within 24 hours, the O-wave and X-wave tracing branches of the F2 layer are automatically distinguished, and the O-wave and X-wave tracing branches of the F2 layer of the frequency-height graph at each time are obtained. It should be noted that the collection of F2 layer tracing branches at each time should cover the entire detection frequency band as much as possible.

[0142] A fitting module 1603 is used to obtain a phase compensation function and an amplitude compensation function by fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height graph at each moment;

[0143] For the frequency-height graph at each moment within 24 hours, determine the tracing branches of the O wave and the X wave of the F2 layer in each frequency-height graph, and obtain the phase compensation parameters and amplitude compensation parameters of each frequency point in each frequency-height graph based on the tracing branches of the O wave and the X wave of the F2 layer, and obtain the frequency-phase parameter graph at different moments within 24 hours, such as Figure 3 As shown; the phase compensation parameters are unwrapped and clustered, as shown Figure 4 As shown, finally, the clustered phase compensation parameters are fitted to obtain the phase compensation function, as shown in Figure 5 shown.

[0144] Optionally, the method of obtaining the amplitude compensation function is similar to the method of obtaining the phase compensation function, and thus will not be described in detail.

[0145] In another feasible implementation, since the result of the amplitude compensation parameter is usually relatively fixed, compensation may be performed directly in the frequency-height graph based on the determined amplitude compensation parameter.

[0146] The separation module 1604 is used to separate the O wave and the X wave in the frequency-height diagram at multiple moments based on the phase compensation function and the amplitude compensation function.

[0147] Substituting the fitted phase compensation function and amplitude compensation function into the original data, we can obtain the frequency-height diagram with X-wave removed and the frequency-height diagram with O-wave eliminated, respectively. The original data is the data received by the double dipole antenna.

[0148] The present invention obtains a phase compensation function and an amplitude compensation function through the tracing branches of the O-wave and the X-wave of the F2 layer, and substitutes the phase compensation function into the original data to realize the separation and extraction of the O-wave and the X-wave, so that the separated results are still stored in the form of original data, which is convenient for storing the separation results and further processing the separated original data, and can avoid the interference caused by the simultaneous existence of the O-wave and the X-wave when the original data is used for direction finding.

[0149] Fig.17 An example of a physical structure diagram of an electronic device is shown in FIG. Fig.17As shown, the electronic device may include: a processor 1710, a communication interface 1720, a memory 1730 and a communication bus 1740, wherein the processor 1710, the communication interface 1720 and the memory 1730 communicate with each other through the communication bus 1740. The processor 1710 may call the logic instructions in the memory 1730 to execute the method for separating the ionospheric O-wave and the X-wave, the method comprising: acquiring the signal echo data of the ionosphere at multiple times within 24 hours, and preprocessing the signal echo data at each time to obtain the frequency-height diagram at each time; determining the phase compensation parameter and the amplitude compensation parameter of each frequency point in the frequency-height diagram at each time according to the trace branches of the O-wave and the X-wave in the F2 layer of the frequency-height diagram at each time; fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each time to obtain the phase compensation function and the amplitude compensation function; and separating the O-wave and the X-wave in the frequency-height diagram at multiple times based on the phase compensation function and the amplitude compensation function.

[0150] In addition, the logic instructions in the above-mentioned memory 1730 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0151] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the method for separating ionospheric O waves and X waves provided by the above methods, the method including: acquiring signal echo data of the ionosphere at multiple times within 24 hours, and preprocessing the signal echo data at each time to obtain a frequency-height diagram at each time; determining a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency-height diagram at each time according to the tracing branches of the O waves and X waves in the F2 layer of the frequency-height diagram at each time; fitting a phase compensation function and an amplitude compensation function according to the phase compensation parameters and the amplitude compensation parameters corresponding to the frequency-height diagram at each time; and separating the O waves and X waves in the frequency-height diagrams at multiple times based on the phase compensation function and the amplitude compensation function.

[0152] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the method for separating ionospheric O waves and X waves provided by the above methods, the method comprising: acquiring signal echo data of the ionosphere at multiple times within 24 hours, and preprocessing the signal echo data at each time to obtain a frequency-height diagram at each time; determining a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency-height diagram at each time according to the tracing branches of the O waves and X waves in the F2 layer of the frequency-height diagram at each time; fitting a phase compensation function and an amplitude compensation function according to the phase compensation parameters and the amplitude compensation parameters corresponding to the frequency-height diagram at each time; and separating the O waves and X waves in the frequency-height diagrams at multiple times based on the phase compensation function and the amplitude compensation function.

[0153] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0154] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating ionospheric O-waves and X-waves, characterized in that: include: Acquire signal echo data of the ionosphere at multiple times within 24 hours, and pre-process the signal echo data at each time to obtain a frequency-height diagram at each time; Determine the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment; A phase compensation function and an amplitude compensation function are obtained by fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height graph at each moment; The O wave and the X wave in the frequency-height diagram at multiple moments are separated based on the phase compensation function and the amplitude compensation function.

2. The method for separating ionospheric O-waves and X-waves according to claim 1, characterized in that: Before the step of determining the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment, the method further comprises: Traversing the peak value of each frequency point in the frequency-height graph at each moment from high to low, and determining a double bifurcation portion where two peak values ​​appear simultaneously; determining a point at a higher range gate position in the double bifurcation portion as an O-wave trace, and determining a point at a lower range gate position as an X-wave trace; The trace branches of the O wave and the X wave in the F2 layer are determined according to the O wave trace and the X wave trace.

3. The method for separating ionospheric O-waves and X-waves according to claim 1, characterized in that: The step of determining the phase compensation parameter and amplitude compensation parameter of each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment specifically comprises: In the case where both the O-wave trace and the X-wave trace exist at the frequency point, the amplitude and the phase shift when the difference between two peak points in the data sequence of the frequency point is maximized are determined as the phase compensation parameter and the amplitude compensation parameter; In the case that only O-wave traces or X-wave traces exist at the frequency point, the phase compensation parameter and the amplitude compensation parameter of the frequency point are determined according to the type of traces to be separated.

4. The method for separating ionospheric O-waves and X-waves according to claim 1, characterized in that: Before the step of fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency height diagram at each moment to obtain the phase compensation function and the amplitude compensation function, the method further includes: The O wave and the X wave in the F2 layer of the frequency height diagram at each moment are eliminated and separated based on the phase compensation parameter and the amplitude compensation parameter.

5. The method for separating ionospheric O-waves and X-waves according to claim 4, characterized in that: After the step of eliminating and separating the O wave and the X wave in the F2 layer of the frequency height diagram at each moment based on the phase compensation parameter and the amplitude compensation parameter, the method further includes: The separation effect of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment is observed, and when the separation effect does not meet the preset separation condition, a low confidence value is set for the phase compensation parameter and the amplitude compensation parameter.

6. The method for separating ionospheric O-waves and X-waves according to any one of claims 1 to 5, characterized in that: The step of fitting the phase compensation function and the amplitude compensation function according to the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height graph at each moment specifically includes: The phase compensation parameter and the amplitude compensation parameter corresponding to the frequency height diagram at each moment are unwound and clustered, and the phase compensation function and the amplitude compensation function are obtained by fitting.

7. An ionospheric O-wave and X-wave separation device, characterized in that: include: An acquisition module is used to acquire signal echo data of the ionosphere at multiple times within 24 hours, and pre-process the signal echo data at each time to obtain a frequency-height diagram at each time; A determination module, for determining a phase compensation parameter and an amplitude compensation parameter for each frequency point in the frequency height diagram at each moment according to the tracing branches of the O wave and the X wave in the F2 layer of the frequency height diagram at each moment; A fitting module, used for fitting the phase compensation parameter and the amplitude compensation parameter corresponding to the frequency-height diagram at each moment to obtain a phase compensation function and an amplitude compensation function; A separation module is used to separate O waves and X waves in the frequency-height diagrams at multiple moments based on the phase compensation function and the amplitude compensation function.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for separating ionospheric O waves and X waves as described in any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for separating ionospheric O-waves and X-waves as claimed in any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for separating ionospheric O-waves and X-waves as claimed in any one of claims 1 to 6 is implemented.

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