Imaging method and device of vehicle-mounted frequency modulation continuous wave ice radar and electronic equipment

Abstract

The invention provides an imaging method and device of a vehicle-mounted frequency modulation continuous wave ice radar and electronic equipment, and can be applied to the technical field of glacier detection and the technical field of signal processing. The method comprises the steps of performing frequency mixing processing on a difference frequency time sequence signal to be extracted based on a predetermined delay line corresponding to a predetermined delay duration so as to extract a nonlinear phase from the difference frequency time sequence signal to be extracted; estimating the nonlinear phase to obtain an estimated emission nonlinear phase; correcting the difference frequency time sequence signal of the shallow surface layer of the ice cover according to the estimated emission non-linear phase to obtain a corrected time sequence signal of which the non-linear phase is removed; according to a predetermined function, removing a residual phase from the corrected time sequence signal to obtain a target time sequence signal; performing motion error compensation on the target time sequence signal according to the motion compensation function to obtain a compensation time sequence signal; and performing Fourier transform processing on the compensation time sequence signal to obtain an image corresponding to the target object.

Description

Technical Field

[0001] The present disclosure relates to the fields of glacier detection technology and signal processing technology, and more specifically, to an imaging method, device and electronic equipment of a vehicle-mounted frequency-modulated continuous-wave ice radar. Background Art

[0002] Compared with traditional pulse radar, FMCW radar has the advantages of higher range resolution, stronger penetration and the ability to eliminate range blind spots. Therefore, FMCW radar is widely used in the field of high-precision ranging and imaging. The vehicle-mounted FMCW ice radar can be used to detect shallow glaciers, and the measured data can be used to calculate the accumulation rate of the ice sheet surface, which is an important parameter for calculating the mass balance of glaciers and ice sheets and estimating sea level rise.

[0003] In the process of realizing the concept of the present disclosure, the inventors found that at least one problem in the related art is that the detection of the frequency modulated continuous wave radar is affected by the nonlinear phase, thereby reducing the measurement accuracy and the imaging resolution. Summary of the invention

[0004] In view of this, the present disclosure provides an imaging method, device and electronic equipment of a vehicle-mounted frequency modulated continuous wave ice radar.

[0005] One aspect of the present disclosure provides an imaging method of a vehicle-mounted frequency modulated continuous wave ice radar, comprising:

[0006] Based on a predetermined delay line corresponding to a predetermined delay time, a mixing process is performed on the difference frequency timing signal to be extracted to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is the difference between the transmitted nonlinear phase and the received nonlinear phase after a predetermined delay time; the nonlinear phase is estimated to obtain an estimated transmitted nonlinear phase; based on the estimated transmitted nonlinear phase, the difference frequency timing signal of the shallow surface layer of the ice sheet is corrected to obtain a corrected timing signal from which the nonlinear phase has been removed; based on a predetermined function, the residual phase is removed from the corrected timing signal to obtain a target timing signal; based on a motion compensation function, the target timing signal is motion error compensated to obtain a compensated timing signal; the compensated timing signal is Fourier transformed to obtain an imaging corresponding to the target object.

[0007] According to an embodiment of the present disclosure, based on a predetermined delay line corresponding to a predetermined delay time length, a difference frequency timing signal to be extracted is mixed so as to extract a nonlinear signal from the difference frequency timing signal to be extracted, including: based on a predetermined delay line corresponding to a predetermined delay time length, obtaining a difference frequency timing signal to be extracted corresponding to a predetermined delay time length; constructing an ideal difference frequency timing signal according to the difference frequency timing signal to be extracted; and conjugate multiplying the difference frequency timing signal to be extracted and the ideal difference frequency timing signal to achieve mixing of the difference frequency timing signal to be extracted and the ideal difference frequency timing signal.

[0008] According to an embodiment of the present disclosure, the difference frequency timing signal of the shallow layer of the ice cover is corrected according to the estimated transmission nonlinear phase to obtain a corrected timing signal with the nonlinear phase removed, including: determining an integral path corresponding to the difference frequency timing signal of the shallow layer of the ice cover according to the estimated transmission nonlinear phase; performing a matching Fourier transform on the difference frequency timing signal of the shallow layer of the ice cover according to the integral path corresponding to the difference frequency timing signal of the shallow layer of the ice cover to obtain a corrected timing signal with the nonlinear phase removed.

[0009] According to an embodiment of the present disclosure, the residual phase is removed from the correction timing signal according to a predetermined function to obtain a target timing signal, including: multiplying the predetermined function with the correction timing signal to remove the residual phase from the correction timing signal to obtain the target timing signal.

[0010] According to an embodiment of the present disclosure, motion error compensation is performed on a target timing signal according to a motion compensation function to obtain a compensated timing signal, including: performing an inverse fast Fourier transform in distance and an inverse fast Fourier transform in azimuth to obtain a target time domain signal; multiplying the target time domain signal by the compensation function to obtain a compensated timing signal to perform motion error compensation on the target timing signal.

[0011] According to an embodiment of the present disclosure, Fourier transform processing is performed on the compensation timing signal to obtain imaging corresponding to the target object, including: compressing and interpolating the compensation timing signal to obtain a focusing timing signal; performing a fast Fourier transform in distance and an inverse fast Fourier transform in azimuth on the focusing timing signal to obtain imaging corresponding to the target object.

[0012] According to an embodiment of the present disclosure, the compensation timing signal is compressed and interpolated to obtain a focusing timing signal, including: multiplying the compensation timing signal with a filter function to obtain a compressed signal to complete the focusing of the target object at a reference distance; interpolating the compressed signal to obtain a focusing timing signal to complete the focusing of the target object at a distance other than the reference distance.

[0013] According to an embodiment of the present disclosure, the filter function includes a range-frequency modulation filter function, which is obtained according to the movement speed of the ice radar and the shortest distance from the target object to the movement direction of the ice radar.

[0014] A second aspect of the present disclosure provides an imaging device of a vehicle-mounted frequency modulated continuous wave ice radar, comprising:

[0015] A mixing module, used for mixing the difference frequency timing signal to be extracted based on a predetermined delay line corresponding to a predetermined delay time length, so as to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is a difference between a transmitting nonlinear phase and a receiving nonlinear phase after a predetermined delay time length;

[0016] An estimation module, used for estimating the nonlinear phase to obtain an estimated transmission nonlinear phase;

[0017] A correction module, used to correct the difference frequency time series signal of the shallow surface layer of the ice sheet according to the estimated transmission nonlinear phase, so as to obtain a corrected time series signal with the nonlinear phase removed;

[0018] A removal module, used for removing the residual phase from the correction timing signal according to a predetermined function to obtain a target timing signal;

[0019] A compensation module, used for performing motion error compensation on the target timing signal according to a motion compensation function to obtain a compensated timing signal;

[0020] The imaging module is used to perform Fourier transform processing on the compensated time series signal to obtain an imaging corresponding to the target object.

[0021] Another aspect of the present disclosure provides an electronic device, comprising:

[0022] one or more processors;

[0023] a memory for storing one or more programs,

[0024] When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described above.

[0025] According to an embodiment of the present disclosure, a nonlinear phase is extracted from a difference frequency timing signal to be extracted of a frequency modulated continuous wave radar through mixing processing, and a transmission nonlinear phase in the nonlinear phase is estimated using a coherent integration method. The estimated transmission nonlinear phase is used to correct the difference frequency timing signal of the shallow surface layer of the ice sheet, and then a compensation function is used to perform range migration correction on the target timing signal from which the nonlinear phase has been removed, to obtain an imaging corresponding to the target object. Due to the correction of the nonlinear phase, the measurement accuracy of the radar is higher and a smaller error can be maintained even when applied to large-range measurements at longer distances. The nonlinear correction is combined with the range migration correction to achieve high-resolution imaging of underground targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0027] Figure 1 The working principle diagram of the vehicle-mounted frequency modulated continuous wave ice radar according to the embodiment of the present disclosure is schematically shown;

[0028] Figure 2 A flow chart schematically shows an imaging method of a vehicle-mounted frequency modulated continuous wave ice radar according to an embodiment of the present disclosure;

[0029] Figure 3 Schematically shows the initial imaging effect without any correction according to the embodiment of the present disclosure;

[0030] Figure 4 Schematically illustrates an ideal imaging effect according to an embodiment of the present disclosure;

[0031] Figure 5 The imaging effect without nonlinear phase correction according to the embodiment of the present disclosure is schematically shown;

[0032] Figure 6 The imaging effect of the imaging method of the vehicle-mounted frequency modulated continuous wave ice radar according to the embodiment of the present disclosure is schematically shown;

[0033] Figure 7 A schematic cross-sectional diagram of range imaging according to an embodiment of the present disclosure is schematically shown;

[0034] Figure 8 The imaging process of the vehicle-mounted FMCW ice radar according to the embodiment of the present disclosure is schematically shown;

[0035] Fig. 9 A block diagram of an imaging device of a vehicle-mounted frequency modulated continuous wave ice radar according to an embodiment of the present disclosure is schematically shown;

[0036] Fig.10A block diagram of an electronic device suitable for implementing an imaging method of a vehicle-mounted frequency modulated continuous wave ice radar according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0038] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0039] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0040] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0041] In the embodiments of the present disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0042] In the embodiments of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

[0043] Since most shallow ice radar equipment is a frequency modulated continuous wave system, which belongs to an ultra-wideband system, there is usually a nonlinear phase in the transmission signal of the ice radar, which will reduce the measurement accuracy and imaging quality of the radar, especially when it comes to large-scale detection at a long distance. At the same time, the nonlinear phase will also cause large side lobes in the imaging, resulting in unclear separation between glacier layers, resulting in errors in calculating the accumulation rate and affecting the inversion of related parameters.

[0044] Existing FMCW radar imaging technology is mostly used for imaging ground targets, and there is almost no mature imaging technology for underground targets. Although nonlinear correction is performed in related technologies, motion compensation is not performed on the corrected results, resulting in the inability to focus on some targets, resulting in low resolution of the generated images.

[0045] In view of this, an embodiment of the present disclosure provides an imaging method of a vehicle-mounted frequency modulated continuous wave ice radar, comprising:

[0046] Based on a predetermined delay line corresponding to a predetermined delay time, a mixing process is performed on the difference frequency timing signal to be extracted to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is the difference between the transmitted nonlinear phase and the received nonlinear phase after a predetermined delay time; the nonlinear phase is estimated to obtain an estimated transmitted nonlinear phase; based on the estimated transmitted nonlinear phase, the difference frequency timing signal of the shallow surface layer of the ice sheet is corrected to obtain a corrected timing signal from which the nonlinear phase has been removed; based on a predetermined function, the residual phase is removed from the corrected timing signal to obtain a target timing signal; based on a motion compensation function, the target timing signal is motion error compensated to obtain a compensated timing signal; the compensated timing signal is Fourier transformed to obtain an imaging corresponding to the target object.

[0047] Figure 1 The working principle diagram of the vehicle-mounted FMCW ice radar according to an embodiment of the present disclosure is schematically shown.

[0048] It should be noted that Figure 1 What is shown are merely examples of application scenarios to which the embodiments of the present disclosure can be applied, in order to help those skilled in the art understand the technical content of the present disclosure, but it does not mean that the embodiments of the present disclosure cannot be used in other devices, systems, environments or scenarios.

[0049] like Figure 1 As shown, the snowmobile drags the on-board FMCW radar device along the direction parallel to the ice surface at a constant speed V, where the x-axis is parallel to the ice surface, the y-axis is the ice depth direction, O is the origin of the coordinate system, and the beam width of the radar is shown in the figure.

[0050] According to an embodiment of the present disclosure, taking 9 radar detection target points as an example, they are (-20, 60), (0, 60), (20, 60), (-20, 80), (0, 80), (20, 80), (-20, 100), (0, 100), and (20, 100), respectively.

[0051] According to an embodiment of the present disclosure, when the radar scans the target point Q (x c ,y c ), the antenna phase center is at point Q' (x n ,y n ). According to the imaging geometry, the instantaneous slant range R between the radar antenna phase center position and the target point can be obtained according to the following formula (1).

[0052] (1)

[0053] in, , t r is the distance to speed time, t m is the azimuth slow time, R0 is the shortest distance between point Q' and point Q (zero Doppler slant distance), .

[0054] According to the embodiment of the present disclosure, the above formula (1) is r =0 first-order Taylor expansion It can be expressed as formula (2).

[0055] (2)

[0056] in, It is the range migration error caused by platform motion during radar frequency modulation.

[0057] According to an embodiment of the present disclosure, the transmission signal of the vehicle-mounted frequency modulation continuous wave radar is a linear frequency modulation continuous wave signal in a sawtooth shape. It can be expressed as the following formula (3).

[0058] (3)

[0059] Among them, T p is the frequency modulation width, is the center frequency of the transmitted signal, K r is the modulation frequency in the distance direction, .

[0060] By comparing the above formula (2) with the traditional synthetic aperture radar, it can be seen that the modulation time of the FMCW signal is relatively long and is no longer applicable to the stop-and-go model of the traditional synthetic aperture radar.

[0061] Figure 2 The flowchart of the imaging method of the vehicle-mounted frequency modulated continuous wave ice radar according to the embodiment of the present disclosure is schematically shown.

[0062] like Figure 2 As shown, the method 200 includes operations S210 to S260.

[0063] In operation S210, a mixing process is performed on the difference frequency time series signal to be extracted based on a predetermined delay line corresponding to a predetermined delay time length, so as to extract a nonlinear phase from the difference frequency time series signal to be extracted.

[0064] In operation S220, the nonlinear phase is estimated to obtain an estimated transmit nonlinear phase.

[0065] In operation S230, the difference frequency time series signal of the shallow layer of the ice sheet is corrected according to the estimated transmission nonlinear phase to obtain a corrected time series signal from which the nonlinear phase has been removed.

[0066] In operation S240, the residual phase is removed from the correction timing signal according to a predetermined function to obtain a target timing signal.

[0067] In operation S250, motion error compensation is performed on the target time series signal according to the motion compensation function to obtain a compensated time series signal.

[0068] In operation S260, Fourier transform processing is performed on the compensated time series signal to obtain an imaging corresponding to the target object.

[0069] According to an embodiment of the present disclosure, the nonlinear phase is the difference between the transmission nonlinear phase and the reception nonlinear phase after a predetermined delay time, the transmission nonlinear phase corresponds to the transmission signal, and the reception nonlinear phase corresponds to the reception signal. The nonlinear phase can be expressed as the following formula (4).

[0070] (4)

[0071] in, is the nonlinear phase in the difference frequency time series signal to be extracted, τ ref The scheduled delay time is is the transmitting nonlinear phase, To receive nonlinear phase.

[0072] According to an embodiment of the present disclosure, a mixer may be used to perform mixing processing on the difference frequency timing signal to be extracted, where the difference frequency timing signal to be extracted is an echo signal received by the receiving antenna of the radar after a predetermined delay time. It can be expressed as the following formula (5).

[0073] (5)

[0074] Where c is the speed of electromagnetic waves in the ice layer, and c=0.185 m / ns is commonly used.

[0075] According to an embodiment of the present disclosure, a coherent integration method may be used to estimate a transmission nonlinear phase from a difference frequency timing signal to be extracted.

[0076] According to the embodiments of the present disclosure, the detection distance of the shallow ice radar is short, and it can only accurately detect about 100 m in the ice layer. Therefore, the maximum round-trip delay time of the electromagnetic wave in the ice layer is only about 1 us. Therefore, when the delay time is very small, the estimated emission nonlinear phase can be obtained by the Lagrange middle value theorem. , the estimated phase can be expressed as the following formula (6).

[0077] (6)

[0078] Where C is a constant.

[0079] According to an embodiment of the present disclosure, matched Fourier transform can be used to correct the difference frequency time series signal of the shallow surface layer of the ice sheet to obtain a corrected time series signal with the nonlinear phase removed.

[0080] According to an embodiment of the present disclosure, the predetermined function It can be expressed as the following formula (7).

[0081] (7)

[0082] in, Represents the distance frequency.

[0083] According to an embodiment of the present disclosure, the residual phase is an additional phase term introduced into the difference frequency timing signal to be extracted due to the modulation characteristics of the transmitted signal and the movement of the radar platform. The existence of the residual phase will affect the distance resolution and imaging quality of the radar signal, so the residual phase is eliminated through a predetermined function.

[0084] According to an embodiment of the present disclosure, the motion error is the error generated by the vehicle-mounted FMCW ice radar platform during continuous motion. IPMC It can be expressed as the following formula (8).

[0085] (8)

[0086] in, is the azimuthal frequency and λ is the wavelength.

[0087] According to the embodiment of the present disclosure, in order to better reflect the effect of the imaging method of the vehicle-mounted FMCW ice radar of the embodiment of the present disclosure, the vehicle-mounted FMCW ice radar is simulated according to the simulation parameters shown in Table 1 below, so as to Figure 3~Figure 7 The effect of the imaging method of the vehicle-mounted FMCW ice radar in the embodiment of the present disclosure is illustrated. Figure 1 Take 9 target points in as an example.

[0088] Table 1

[0089]

[0090] Among them, FMCW (Frequency Modulated Continuous Wave) is the abbreviation of frequency modulated continuous wave, RF (Radio Frequency) is the abbreviation of radio frequency, and PRF (pulse repetition frequency) is the pulse repetition frequency.

[0091] Figure 3 The figure schematically shows the initial imaging effect without any correction according to the embodiment of the present disclosure.

[0092] like Figure 3 As shown in the figure, the horizontal axis represents the azimuth migration, and the vertical axis represents the range migration. Due to the influence of the nonlinear phase, the migration of the 9 target points in the range direction is more obvious. The nonlinear phase added in the simulation can be expressed as the following formula (9).

[0093] (9)

[0094] Among them, A sl is the first periodic term parameter, here we take , is the second periodic term parameter, take a1 is the cubic nonlinear term coefficient, , a2 is the coefficient of the fourth-order nonlinear term, .

[0095] Figure 4 The ideal imaging effect according to the embodiment of the present disclosure is schematically shown.

[0096] like Figure 4 As shown, the images of the nine target points are all well focused.

[0097] According to an embodiment of the present disclosure, the abscissa represents the azimuth migration, and the ordinate represents the distance migration.

[0098] Figure 5 The imaging effect without nonlinear phase correction according to the embodiment of the present disclosure is schematically shown.

[0099] like Figure 5 As shown in the figure, the horizontal axis represents the azimuth migration, and the vertical axis represents the range migration. Due to the lack of nonlinear phase correction, the 9 target points have obvious tailing in the range direction, the imaging cannot be focused, and the range information is inaccurate, which affects the subsequent calculation of the accumulation rate.

[0100] Figure 6 The imaging effect of the imaging method of the vehicle-mounted frequency modulated continuous wave ice radar according to an embodiment of the present disclosure is schematically shown.

[0101] like Figure 6 As shown in the figure, the horizontal axis represents the azimuth migration and the vertical axis represents the distance migration. Figure 6 and Figure 5 It can be clearly seen that the imaging that corrects the nonlinear phase and then compensates for the motion error can effectively suppress the tailing in the range direction, and the imaging of the target point is more focused.

[0102] Figure 7 A cross-sectional schematic diagram of range imaging according to an embodiment of the present disclosure is schematically shown.

[0103] like Figure 7 As shown, in the cross-sectional view at (0, 80), the curve after correction by the embodiment 200 is closer to the ideal state.

[0104] According to an embodiment of the present disclosure, a nonlinear phase is extracted from a difference frequency timing signal to be extracted of a frequency modulated continuous wave radar through mixing processing, and a transmission nonlinear phase in the nonlinear phase is estimated using a coherent integration method. The estimated transmission nonlinear phase is used to correct the difference frequency timing signal of the shallow surface layer of the ice sheet, and then a compensation function is used to perform range migration correction on the target timing signal from which the nonlinear phase has been removed, to obtain an imaging corresponding to the target object. Due to the correction of the nonlinear phase, the measurement accuracy of the radar is higher and a smaller error can be maintained even when applied to large-range measurements at longer distances. The nonlinear correction is combined with the range migration correction to achieve high-resolution imaging of underground targets.

[0105] According to an embodiment of the present disclosure, based on a predetermined delay line corresponding to a predetermined delay time length, a difference frequency timing signal to be extracted is mixed so as to extract a nonlinear signal from the difference frequency timing signal to be extracted, including: based on a predetermined delay line corresponding to a predetermined delay time length, obtaining a difference frequency timing signal to be extracted corresponding to a predetermined delay time length; constructing an ideal difference frequency timing signal according to the difference frequency timing signal to be extracted; and conjugate multiplying the difference frequency timing signal to be extracted and the ideal difference frequency timing signal to achieve mixing of the difference frequency timing signal to be extracted and the ideal difference frequency timing signal.

[0106] According to an embodiment of the present disclosure, the difference frequency timing signal to be extracted can be expressed as the following formula (10).

[0107] (10)

[0108] According to the embodiment of the present disclosure, an ideal difference frequency timing signal is constructed according to the difference frequency timing signal to be extracted. The process can be expressed as the following formula (10).

[0109] (11)

[0110] According to an embodiment of the present disclosure, the mixing result obtained by conjugate multiplying the difference frequency timing signal to be extracted and the ideal difference frequency timing signal can be expressed as the following formula (12).

[0111] (12)

[0112] The nonlinear phase is expressed as .

[0113] According to an embodiment of the present disclosure, the difference frequency timing signal of the shallow layer of the ice sheet is corrected according to the estimated transmission nonlinear phase to obtain a corrected timing signal with the nonlinear phase removed, including: determining an integral path corresponding to the difference frequency timing signal to be extracted according to the target estimated phase; and performing a matching Fourier transform on the difference frequency timing signal to be extracted according to the integral path corresponding to the difference frequency timing signal to be extracted to obtain a corrected timing signal with the nonlinear phase removed.

[0114] According to the embodiments of the present disclosure, the matched Fourier transform is similar to the traditional Fourier transform form, and the difference frequency timing signal to be extracted can be converted into a linear expression by simply changing the integral path, thereby removing the nonlinear phase.

[0115] According to an embodiment of the present disclosure, the integral path corresponding to the difference frequency timing signal to be extracted It can be expressed as the following formula (13).

[0116] (13)

[0117] According to an embodiment of the present disclosure, based on the determined integration path, the process of matching Fourier transform of the difference frequency time series signal of the shallow surface layer of the ice sheet can be expressed as the following formula (14).

[0118] (14)

[0119] in, To correct the timing signal, is the difference frequency time series data of the shallow layer of the ice sheet to be corrected, the distance frequency The value range is , is the sampling frequency of the analog-to-digital converter.

[0120] According to an embodiment of the present disclosure, the corrected timing signal after matching Fourier transform can be expressed as the following formula (15).

[0121] (15)

[0122] According to the embodiments of the present disclosure, after the nonlinear phase is corrected by matching Fourier transform, each target point is focused into a Sinque function at the corresponding position, the trailing side lobes are effectively suppressed, the main peak is clearer, closer to the real physical scene, and the distortion caused by the nonlinear effect is reduced.

[0123] According to an embodiment of the present disclosure, the residual phase is removed from the correction timing signal according to a predetermined function to obtain a target timing signal, including: multiplying the predetermined function with the correction timing signal to remove the residual phase from the correction timing signal to obtain the target timing signal.

[0124] According to an embodiment of the present disclosure, the removal of the residual phase can be performed in the frequency domain by multiplying the above formula (7) with the above formula (15) to remove the residual video phase other than the nonlinear phase. The target timing signal has more accurate phase information, which can make the radar detection result have a smaller error, so as to facilitate the subsequent range migration correction and imaging.

[0125] According to an embodiment of the present disclosure, motion error compensation is performed on a target timing signal according to a motion compensation function to obtain a compensated timing signal, including: performing an inverse fast Fourier transform in distance and an inverse fast Fourier transform in azimuth to obtain a target time domain signal; multiplying the target time domain signal by the compensation function to obtain a compensated timing signal to perform motion error compensation on the target timing signal.

[0126] According to an embodiment of the present disclosure, the target time domain signal includes range information in the time domain and azimuth information in the frequency domain. The compensation function is usually designed based on the motion model of the radar platform (such as speed, acceleration, etc.) and the modulation characteristics of the signal.

[0127] According to an embodiment of the present disclosure, the value range of the azimuth frequency in the above formula (8) can be . PRF is the frequency modulated pulse repetition frequency.

[0128] According to the embodiments of the present disclosure, after the nonlinear characteristics are corrected, motion error compensation is performed to further improve the accuracy of vehicle-mounted FMCW ice radar imaging and reduce blur and distortion caused by platform motion.

[0129] According to an embodiment of the present disclosure, Fourier transform processing is performed on the compensation timing signal to obtain imaging corresponding to the target object, including: compressing and interpolating the compensation timing signal to obtain a focusing timing signal; performing a fast Fourier transform in distance and an inverse fast Fourier transform in azimuth on the focusing timing signal to obtain imaging corresponding to the target object.

[0130] According to the embodiments of the present disclosure, the compensation timing signal is compressed and interpolated to obtain a focusing timing signal, which can not only achieve focusing at the reference distance, but also achieve focusing at the non-reference distance. For partial focusing at the non-reference distance, it is necessary to compensate for the residual RCMC (Range Cell Migration Correction) and residual SRC (Scene-to-Scene Range Cell Migration) and compress the residual orientation.

[0131] According to an embodiment of the present disclosure, a fast Fourier transform in distance and an inverse fast Fourier transform in azimuth are performed on the focus timing signal to obtain an imaging corresponding to the target object, including: performing a fast Fourier transform in distance and an inverse fast Fourier transform in azimuth on the focus timing signal, then multiplying the reference distance by a frequency shift function to move the target point to a corresponding position in the scene, and finally performing an inverse fast Fourier transform in azimuth to complete azimuth compression to obtain the target imaging.

[0132] According to an embodiment of the present disclosure, the compensation timing signal is compressed and interpolated to obtain a focusing timing signal, including: multiplying the compensation timing signal with a filter function to obtain a compressed signal to complete the focusing of the target object at a reference distance; interpolating the compressed signal to obtain a focusing timing signal to complete the focusing of the target object at a distance other than the reference distance.

[0133] According to an embodiment of the present disclosure, the compensation time series signal is multiplied by the filter function to achieve consistent compression, so that the signal of the target object at the reference distance is focused, and only partially focused at the non-reference distance. The compressed signal can be expressed as the following formula (16).

[0134] (16)

[0135] in, For compressed signal.

[0136] According to an embodiment of the present disclosure, in order to compensate for the residual phase at other positions and complete the residual RCMC, residual SRC and residual azimuth compression, an interpolation process may be performed. The replacement expression is as follows (17).

[0137] (17)

[0138] According to an embodiment of the present disclosure, for the above formula (17) at t r = 0, the interpolation variable substitution expression can be rewritten as follows (18).

[0139] (18)

[0140] According to an embodiment of the present disclosure, the above formula (18) is used to modify t in the above formula (16). r Replace to achieve interpolation.

[0141] According to the embodiments of the present disclosure, the signal after nonlinear phase correction and range migration correction is compressed and interpolated, so that the target object is focused at both the reference distance and the non-reference distance, making the imaging details more prominent.

[0142] According to an embodiment of the present disclosure, the filter function includes a range-frequency modulation filter function, which is obtained according to the movement speed of the ice radar and the shortest distance from the target object to the movement direction of the ice radar.

[0143] According to an embodiment of the present disclosure, a filter function is constructed to compress the compensation time series signal, thereby achieving focusing of the target object at a reference distance. The filter function can be expressed as the following formula (19).

[0144] (19)

[0145] Among them, R c is the shortest distance from the target object to the direction of movement of the ice radar.

[0146] In order to better understand the overall imaging process of the vehicle-mounted FMCW ice radar in the embodiment of the present disclosure, the following will be Figure 8 The whole processing process is further explained.

[0147] Figure 8 The imaging process diagram of the vehicle-mounted FMCW ice radar according to an embodiment of the present disclosure is schematically shown.

[0148] like Figure 8 As shown, the embodiment 800 includes operations S810 to S880.

[0149] In operation S810, a difference frequency timing signal to be extracted is input.

[0150] In operation S820, a nonlinear phase is estimated.

[0151] In operation S830, matching Fourier transform is performed on the difference frequency time series signal of the shallow surface layer of the ice sheet to remove the nonlinear phase.

[0152] In operation S840, the residual phase is removed, and an inverse fast Fourier transform in the range direction and a fast Fourier transform in the azimuth direction are performed, and operation S850 is performed.

[0153] In operation S850, motion error compensation is performed.

[0154] In operation S860, compression processing and interpolation processing are performed, and a fast Fourier transform in the range direction is performed, and then operation S870 is performed.

[0155] In operation S870, the reference distance is translated, and an inverse fast Fourier transform is performed in the azimuth direction, and operation S880 is performed.

[0156] In operation S880, imaging corresponding to the target object is output.

[0157] Fig. 9 A block diagram of a device for denoising ice radar-based horizon data according to an embodiment of the present disclosure is schematically shown.

[0158] like Fig. 9 As shown, the apparatus 900 includes a mixing module 910 , an estimation module 920 , a correction module 930 , a removal module 940 , a compensation module 950 , and an imaging module 960 .

[0159] A mixing module is used to perform mixing processing on the difference frequency timing signal to be extracted based on a predetermined delay line corresponding to a predetermined delay time length, so as to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is the difference between the transmitted nonlinear phase and the received nonlinear phase after the predetermined delay time length.

[0160] The estimation module is used to estimate the nonlinear phase to obtain an estimated transmission nonlinear phase.

[0161] The correction module is used to correct the difference frequency time series signal of the shallow surface layer of the ice sheet according to the estimated transmission nonlinear phase, so as to obtain the corrected time series signal with the nonlinear phase removed.

[0162] The removal module is used to remove the residual phase from the correction timing signal according to a predetermined function to obtain the target timing signal.

[0163] The compensation module is used to perform motion error compensation on the target timing signal according to the motion compensation function to obtain a compensated timing signal.

[0164] The imaging module is used to perform Fourier transform processing on the compensated time series signal to obtain an imaging corresponding to the target object.

[0165] According to an embodiment of the present disclosure, the mixing module 910 includes a obtaining submodule, a constructing submodule and a conjugating submodule.

[0166] The obtaining submodule is used to obtain the difference frequency timing signal to be extracted corresponding to the predetermined delay time length based on the predetermined delay line corresponding to the predetermined delay time length.

[0167] The construction submodule is used to construct an ideal difference frequency timing signal according to the difference frequency timing signal to be extracted.

[0168] The conjugate submodule is used to perform conjugate multiplication on the difference frequency timing signal to be extracted and the ideal difference frequency timing signal to achieve mixing of the difference frequency timing signal to be extracted and the ideal difference frequency timing signal.

[0169] According to an embodiment of the present disclosure, the correction module 930 includes a determination submodule and an acquisition submodule.

[0170] The determination submodule is used to determine the integration path corresponding to the difference frequency timing signal to be extracted according to the estimated transmission nonlinear phase.

[0171] A submodule is obtained, which is used to perform a matching Fourier transform on the difference frequency time series signal to be extracted according to an integral path corresponding to the difference frequency time series signal to be extracted, so as to obtain a correction time series signal with the nonlinear phase removed.

[0172] According to an embodiment of the present disclosure, the removal module 940 includes a removal submodule.

[0173] The removal submodule is used to multiply the predetermined function with the correction timing signal to remove the residual phase from the correction timing signal to obtain the target timing signal.

[0174] According to an embodiment of the present disclosure, the compensation module 950 includes a transform submodule and an obtain submodule.

[0175] The transformation submodule is used to perform inverse fast Fourier transform in the range and fast Fourier transform in the azimuth on the target time series signal to obtain the target time domain signal.

[0176] The submodule is used to multiply the target time domain signal by the compensation function to obtain a compensated time series signal to perform motion error compensation on the target time series signal.

[0177] According to an embodiment of the present disclosure, the imaging module 960 includes a processing submodule and an obtaining submodule.

[0178] The processing submodule is used to compress and interpolate the compensation timing signal to obtain a focusing timing signal.

[0179] A submodule is obtained, which is used to perform a fast Fourier transform in the range and an inverse fast Fourier transform in the azimuth on the focusing time series signal to obtain an imaging corresponding to the target object.

[0180] According to an embodiment of the present disclosure, the processing submodule includes a first focusing unit and a second focusing unit.

[0181] The first focusing unit is used to multiply the compensation timing signal with the filter function to obtain a compression signal to complete focusing of the target object at a reference distance.

[0182] The second focusing unit is used to perform interpolation processing on the compressed signal to obtain a focusing timing signal to complete focusing of the target object at a distance other than the reference distance.

[0183] According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits, or at least part of the functions of any one of them can be implemented in one module. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be split into multiple modules for implementation. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be at least partially implemented as hardware circuits, such as field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), systems on chips, systems on substrates, systems on packages, application specific integrated circuits (ASICs), or can be implemented by hardware or firmware in any other reasonable way of integrating or packaging circuits, or can be implemented in any one of the three implementation methods of software, hardware, and firmware, or in any appropriate combination of any of them. Alternatively, according to the embodiments of the present invention, one or more of the modules, submodules, units, and subunits can be at least partially implemented as computer program modules, and when the computer program modules are run, the corresponding functions can be performed.

[0184] For example, any of the mixing module 910, the estimation module 920, the correction module 930, the removal module 940, the compensation module 950, and the imaging module 960 can be combined in one module / unit / subunit for implementation, or any of the modules / units / subunits can be split into multiple modules / units / subunits. Alternatively, at least part of the functions of one or more of the modules / units / subunits can be combined with at least part of the functions of other modules / units / subunits and implemented in one module / unit / subunit. According to an embodiment of the present disclosure, at least one of the mixing module 910, the estimation module 920, the correction module 930, the removal module 940, the compensation module 950 and the imaging module 960 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware and firmware or in any appropriate combination of any of them. Alternatively, at least one of the mixing module 910, the estimation module 920, the correction module 930, the removal module 940, the compensation module 950 and the imaging module 960 can be at least partially implemented as a computer program module, and when the computer program module is executed, the corresponding function can be performed.

[0185] Fig. 9 A block diagram of an electronic device suitable for implementing the method described above according to an embodiment of the present disclosure is schematically shown. Fig. 9 The electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0186] like Fig. 9 As shown, the electronic device 900 according to an embodiment of the present disclosure includes a processor 901, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 902 or a program loaded from a storage part 908 into a random access memory (RAM) 903. The processor 901 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a dedicated microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 901 may also include an onboard memory for caching purposes. The processor 901 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0187] In RAM 903, various programs and data required for the operation of electronic device 900 are stored. Processor 901, ROM 902 and RAM 903 are connected to each other via bus 904. Processor 901 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 902 and / or RAM 903. It should be noted that the program can also be stored in one or more memories other than ROM 902 and RAM 903. Processor 901 can also perform various operations of the method flow according to the embodiment of the present disclosure by executing the program stored in the one or more memories.

[0188] According to an embodiment of the present disclosure, the electronic device 900 may further include an input / output (I / O) interface 909, which is also connected to the bus 904. The electronic device 900 may further include one or more of the following components connected to the input / output (I / O) interface 909: an input portion 906 including a keyboard, a mouse, etc.; an output portion 907 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 908 including a hard disk, etc.; and a communication portion 909 including a network interface card such as a LAN card, a modem, etc. The communication portion 909 performs communication processing via a network such as the Internet. A drive 910 is also connected to the input / output (I / O) interface 909 as needed. A removable medium 911, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 910 as needed, so that a computer program read therefrom is installed into the storage portion 908 as needed.

[0189] According to an embodiment of the present disclosure, the method flow according to an embodiment of the present disclosure can be implemented as a computer software program. For example, an embodiment of the present disclosure includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 909, and / or installed from the removable medium 911. When the computer program is executed by the processor 901, the above-mentioned functions defined in the system of the embodiment of the present disclosure are executed. According to an embodiment of the present disclosure, the system, equipment, device, module, unit, etc. described above can be implemented by a computer program module.

[0190] The present disclosure also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present disclosure is implemented.

[0191] According to an embodiment of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium. For example, it may include, but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device.

[0192] For example, according to an embodiment of the present disclosure, the computer-readable storage medium may include the ROM 902 and / or the RAM 903 described above and / or one or more memories other than the ROM 902 and the RAM 903 .

[0193] An embodiment of the present disclosure also includes a computer program product, which includes a computer program, which contains program code for executing the method provided by the embodiment of the present disclosure. When the computer program product runs on an electronic device, the program code is used to enable the electronic device to implement the ice radar-based layer data denoising method provided by the embodiment of the present disclosure.

[0194] When the computer program is executed by the processor 901, the above functions defined in the system / device of the embodiment of the present disclosure are executed. According to the embodiment of the present disclosure, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0195] In one embodiment, the computer program may be based on a tangible storage medium such as an optical storage device, a magnetic storage device, etc. In another embodiment, the computer program may also be transmitted and distributed in the form of a signal on a network medium, and downloaded and installed through the communication part 909, and / or installed from a removable medium 911. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0196] According to an embodiment of the present disclosure, the program code for executing the computer program provided by the embodiment of the present disclosure can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level process and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on the remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, using an Internet service provider to connect through the Internet).

[0197] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0198] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An imaging method of a vehicle-mounted frequency modulated continuous wave ice radar, comprising: Based on a predetermined delay line corresponding to the predetermined delay time, mixing processing is performed on the difference frequency timing signal to be extracted, so as to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is a difference between a transmitted nonlinear phase and a received nonlinear phase after a predetermined delay time; estimating the nonlinear phase to obtain an estimated transmit nonlinear phase; Correcting the ice sheet shallow layer difference frequency time series signal according to the estimated transmission nonlinear phase to obtain a corrected time series signal from which the nonlinear phase has been removed; According to a predetermined function, removing the residual phase from the correction timing signal to obtain a target timing signal; According to the motion compensation function, the target time series signal is subjected to motion error compensation to obtain a compensated time series signal; The compensated time series signal is subjected to Fourier transform processing to obtain an imaging corresponding to the target object.

2. The method according to claim 1, wherein: The mixing process is performed on the difference frequency time series signal to be extracted based on the predetermined delay line corresponding to the predetermined delay time length to extract the nonlinear signal from the difference frequency time series signal to be extracted, including: Based on a predetermined delay line corresponding to the predetermined delay time length, obtaining a difference frequency timing signal to be extracted corresponding to the predetermined delay time length; Constructing an ideal difference frequency timing signal according to the difference frequency timing signal to be extracted; The difference frequency timing signal to be extracted and the ideal difference frequency timing signal are conjugate multiplied to achieve mixing of the difference frequency timing signal to be extracted and the ideal difference frequency timing signal.

3. The method according to claim 1, wherein: The method of correcting the ice cover shallow layer difference frequency time series signal according to the estimated transmission nonlinear phase to obtain a corrected time series signal with the nonlinear phase removed includes: Determining an integral path corresponding to the ice sheet shallow layer difference frequency time series signal according to the estimated transmission nonlinear phase; According to the integration path corresponding to the ice cover shallow layer difference frequency time series signal, the ice cover shallow layer difference frequency time series signal is matched with Fourier transform to obtain a correction time series signal with the nonlinear phase removed.

4. The method according to claim 1, wherein: The step of removing the residual phase from the correction timing signal according to a predetermined function to obtain a target timing signal comprises: The predetermined function is multiplied by the corrected timing signal to remove the residual phase from the corrected timing signal to obtain the target timing signal.

5. The method according to claim 1, wherein: The step of performing motion error compensation on the target timing signal according to the motion compensation function to obtain a compensated timing signal includes: Performing an inverse fast Fourier transform in terms of range and an inverse fast Fourier transform in terms of azimuth on the target time series signal to obtain a target time domain signal; The target time domain signal is multiplied by the compensation function to obtain the compensated time sequence signal, so as to perform motion error compensation on the target time sequence signal.

6. The method according to claim 1, wherein: The performing Fourier transform processing on the compensated time series signal to obtain an image corresponding to the target object includes: Compressing and interpolating the compensation timing signal to obtain a focusing timing signal; The focusing timing signal is subjected to a fast Fourier transform in the range and an inverse fast Fourier transform in the azimuth to obtain an image corresponding to the target object.

7. The method according to claim 6, wherein: The compressing and interpolating the compensation timing signal to obtain the focusing timing signal comprises: Multiplying the compensated timing signal by a filter function to obtain a compressed signal to complete focusing of the target object at a reference distance; The compressed signal is interpolated to obtain a focusing timing signal to complete focusing of the target object at a distance other than the reference distance.

8. The method according to claim 7, wherein: The filter function comprises a distance-frequency modulation filter function, and the distance-frequency modulation filter function is obtained according to the movement speed of the ice radar and the shortest distance from the target object to the movement direction of the ice radar.

9. An imaging device of a vehicle-mounted frequency modulated continuous wave ice radar, comprising: A mixing module, configured to perform mixing processing on the difference frequency timing signal to be extracted based on a predetermined delay line corresponding to the predetermined delay time length, so as to extract a nonlinear phase from the difference frequency timing signal to be extracted, wherein the nonlinear phase is a difference between a transmitted nonlinear phase and a received nonlinear phase after a predetermined delay time length; An estimation module, used to estimate the nonlinear phase to obtain an estimated transmission nonlinear phase; A correction module, configured to correct the ice sheet shallow layer difference frequency time series signal according to the estimated transmission nonlinear phase, so as to obtain a corrected time series signal from which the nonlinear phase has been removed; A removal module, used for removing the residual phase from the correction timing signal according to a predetermined function to obtain a target timing signal; A compensation module, used for performing motion error compensation on the target timing signal according to a motion compensation function to obtain a compensated timing signal; The imaging module is used to perform Fourier transform processing on the compensated time series signal to obtain an imaging corresponding to the target object.

10. An electronic device, comprising: one or more processors; a memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 8.

Images