A method and apparatus for estimating phase difference change rate measurements guided by time difference measurements

Abstract

The application discloses a kind of phase difference change rate measurement estimation method and device guided by time difference measurement, comprising: obtaining the two-way IQ signal of the same pulse signal of radiation source;Calculate the TDOA rough value of two-way IQ signal;Two-way IQ signal is cross-correlated operation, according to the cross-correlation operation result, curve fitting is carried out in the coordinate point near the TDOA rough value, to calculate TDOA accurate value;Calculate the ambiguous phase difference of two-way IQ signal, and use TDOA accurate value to the ambiguous phase difference is deambiguated, obtain accurate phase difference;Linear fitting is carried out to the accurate phase difference of multiple pulse signals in predetermined time period, and the slope of phase difference curve obtained by fitting is calculated, and the phase difference change rate is obtained.The phase difference change rate obtained by the application has high precision, can obtain unambiguous phase difference under certain conditions, and has small operation amount, is easy to engineering implementation, is especially suitable for real-time requirement high airborne electronic countermeasure reconnaissance equipment and warning equipment.

Description

Technical Field

[0001] This invention belongs to the field of radiation source localization technology, and relates to single-station passive localization technology, and in particular to a method and device for estimating the rate of change of phase difference guided by time difference measurement. Background Technology

[0002] Single-station passive positioning plays a crucial role in electronic reconnaissance applications. Non-cooperative passive positioning of radiation source targets is a key task of electronic reconnaissance. The electronic reconnaissance station first obtains its own position coordinates through a navigation system, then measures parameters such as phase difference, time difference, frequency, and direction of arrival of the radiation source signal. Based on this, various positioning models are used to calculate the radiation source's position coordinates, thus completing the entire positioning process. Interferometers are commonly used in electronic reconnaissance for measuring the direction of arrival of radiation sources. They can be used not only for radar signals but also for communication signals. By measuring the phase difference between signals received by antennas located on different wavefronts, the direction of arrival can be obtained after processing the phase difference, and this can be used as a basis for passive positioning of radiation source targets. Furthermore, phase difference measurement technology has wide applications in many fields, including laser ranging, geological exploration, and ultrasonic measurement, all of which require accurate estimation of the phase difference between two signals received by sensors.

[0003] High-precision measurement of the interferometer's phase difference is a prerequisite for high-precision direction finding, and a high-precision phase difference is also a prerequisite for fitting a high-precision rate of change of phase difference. Interferometer direction finding uses the measured value of the phase difference to estimate the azimuth angle of the radiation source. In traditional phase difference measurement methods, the phase difference has a period of 2π. If it exceeds 2π, phase difference ambiguity will occur, and the true direction of the incoming wave cannot be distinguished. The interferometer direction finding error is related to the distance between the two antennas. To obtain high direction finding accuracy, the distance between the two antennas must be long enough, i.e., a long baseline must be used. However, due to the limited distance between different antennas on a single platform, the baseline length is not long enough, especially for small mobile platforms like fighter jets, where the phase difference is small and phase difference ambiguity exists.

[0004] One quantifiable value that can be obtained for a radiation source is the signal arrival time. Since the distance to the radiation source is unknown, the relative change in its arrival time contains information about the target's state. In traditional measurement schemes, to obtain this information, it is necessary to accurately measure the signal time characteristics in order to obtain the target's velocity and distance information, and thus the location information of the radiation source. Therefore, this method has the disadvantages of being slow and inaccurate. Summary of the Invention

[0005] The present invention aims to propose a method and apparatus for estimating the rate of change of phase difference guided by time difference measurement, so as to improve the accuracy and real-time performance of phase difference measurement.

[0006] According to one aspect of the present invention, a method for estimating the rate of change of phase difference is disclosed, comprising:

[0007] Acquire two IQ signals from the same pulse signal from the radiation source;

[0008] Calculate the arrival time difference between the two IQ signals to obtain a rough TDOA value;

[0009] Cross-correlation is performed on the two IQ signals. Based on the cross-correlation result, curve fitting is performed near the coordinate point corresponding to the rough value of TDOA, and the precise value of TDOA is calculated based on the fitted curve.

[0010] Calculate the ambiguous phase difference between the two IQ signals, and use the precise TDOA value to deambiguate the ambiguous phase difference to obtain the precise phase difference;

[0011] Linear fitting is performed on the precise phase difference of multiple pulse signals within a predetermined time period, and the slope of the fitted phase difference curve is calculated to obtain the phase difference change rate.

[0012] In other examples, the process of performing cross-correlation on the two IQ signals, and then performing curve fitting near the coordinate points corresponding to the approximate TDOA value based on the cross-correlation result, to calculate the precise TDOA value based on the fitted curve, includes:

[0013] Perform cross-correlation calculation on the two IQ signals;

[0014] The parabolic curve of the cross-correlation function is fitted using the multiple delays in the above cross-correlation operation and the magnitude of the cross-correlation operation results corresponding to the delays;

[0015] Based on the parabolic curve, the delay corresponding to the maximum value of the cross-correlation function is obtained by interpolation calculation. The delay is then multiplied by the sampling interval in the cross-correlation operation to obtain the precise TDOA value of the two IQ signals.

[0016] In other examples, the process of deblurring the blurred phase difference using the precise TDOA value to obtain the precise phase difference includes:

[0017] Calculate the fuzzy number K;

[0018] The unambiguous phase difference value is calculated using the following formula:

[0019] In the formula, This is the fuzzy phase difference obtained through cross-correlation calculation.

[0020] According to another aspect of the present invention, a method for estimating the rate of change of phase difference is disclosed, comprising:

[0021] Obtain the rough time difference of arrival of the two IQ signals;

[0022] Obtain the cross-correlation results corresponding to the time difference between the coarse and fine IQ signals when the two signals are separated by several sampling intervals. Perform curve fitting on the cross-correlation results and calculate the time delay corresponding to the maximum cross-correlation value by interpolation as the fine time difference between the two IQ signals.

[0023] Cross-correlation is performed on the two IQ signals, and the phase of the cross-correlation calculation result is taken as the fuzzy phase difference between the two IQ signals. The fuzzy phase difference is then defuzzified using the precise time difference of arrival to obtain a fuzzy and accurate phase difference.

[0024] Linear fitting is performed on the precise phase difference of multiple pulse signals within a predetermined time period, and the slope of the fitted phase difference curve is calculated to obtain the phase difference change rate.

[0025] According to another aspect of the present invention, a phase difference change rate measurement and estimation device is disclosed, comprising:

[0026] The TDOA coarse value calculation unit is used to obtain the coarse arrival time difference between the two IQ signals;

[0027] The TDOA precision value calculation unit is used to obtain the cross-correlation results corresponding to the time difference between the coarse and fine IQ signals, which are separated by several sampling intervals. The cross-correlation results are curve fitted, and the time delay corresponding to the maximum cross-correlation value is calculated by interpolation as the precision arrival time difference between the two IQ signals.

[0028] A phase difference calculation unit is used to perform cross-correlation on two IQ signals, take the phase of the cross-correlation calculation result as the fuzzy phase difference between the two IQ signals, and use the precise time difference of arrival to defuzzify the fuzzy phase difference to obtain an unfuzzy, precise phase difference; and

[0029] The phase difference change rate calculation unit is used to perform linear fitting on the precise phase difference of multiple pulse signals within a predetermined time period, and calculate the slope of the fitted phase difference curve to obtain the phase difference change rate.

[0030] Compared with existing technologies, the phase difference change rate obtained by this invention has higher accuracy, can obtain unambiguous phase difference under certain conditions, and has low computational load, making it easy to implement in engineering. It is particularly suitable for airborne electronic countermeasures reconnaissance equipment and alarm equipment with high real-time requirements. Attached Figure Description

[0031] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1A schematic diagram illustrating the use of two sensors on a single station (platform) to receive target signals;

[0033] Figure 2 This is a schematic diagram of the workflow of the phase difference change rate measurement estimation method guided by time difference measurement according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the composition of a radiation source detection system according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the phase difference change rate measurement and estimation device according to an embodiment of the present invention;

[0036] Figure 5 , Figure 6 This is a schematic diagram illustrating the trend of phase difference variation and the accuracy of phase difference measurement. Detailed Implementation

[0037] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] Figure 1 This diagram illustrates the use of two sensors on a single station (platform) to receive target signals. As shown, taking an airborne platform as an example, ○ represents two antenna elements located on the same airborne platform, △ represents the target, and Δτ... 1,k Δτ represents the time delay between the first antenna element receiving the k-th pulse signal and the target emitting the k-th pulse signal. 2,k The second antenna unit receives the k-th pulse signal relative to the target emitting the k-th pulse signal, and v represents the aircraft's speed.

[0040] Figure 2 This is a schematic diagram illustrating the workflow of a phase difference change rate measurement estimation method guided by time difference measurement according to an embodiment of the present invention. Figure 2 As shown, the method includes the following steps:

[0041] Step 100: Acquire the two IQ signals of the same pulse signal from the radiation source;

[0042] A radiation signal from a radiation source reaches two spatially separated antenna elements on a single platform. After filtering, noise floor amplification, and analog down-conversion, an intermediate frequency (IF) signal is obtained. The IF signal is then converted from analog to digital to obtain a digital signal. Finally, the digital signal is subjected to a Hilbert transform to obtain an IQ signal (complex signal).

[0043] Assume the k-th pulse signal emitted by the target is:

[0044]

[0045] Among them, a[1+a m sin(2πf m n k t s [)] represents amplitude modulation information, t s n is the sampling interval. k =[0,1,2,…,N-1]+(k-1)T / t s .

[0046] The signal received by the first antenna element is:

[0047]

[0048] Where, n 1,k =n k +Δn 1,k ,Δn 1,k =ceil(Δτ) 1,k / t s ).

[0049] The signal received by the second antenna element is:

[0050]

[0051] Where, n 2,k =n k +Δn 2,k ,Δn 2,k =ceil(Δτ) 2,k / t s ).

[0052] Step 200: Calculate the arrival time difference of the two IQ signals to obtain a rough TDOA value;

[0053] For example, the approximate TDOA value of the two IQ signals is obtained by detecting the envelope feature of the IQ signal, that is, by detecting the arrival time of the pulse leading edge of the two IQ signals respectively, and then calculating the difference between the arrival times of the pulse leading edge of the two IQ signals to obtain the approximate TDOA value.

[0054] The TDOA coarse value is calculated by calculating the TDOA coarse value of multiple pulse signals within a predetermined time period, and the average value is calculated after filtering the multiple TDOA coarse values ​​as the final TDOA coarse value.

[0055] Step 300: Perform cross-correlation calculation on the two IQ signals. Based on the cross-correlation result, perform curve fitting near the coordinate points corresponding to the approximate TDOA value to calculate the precise TDOA value based on the fitted curve. Specifically, this includes the following steps:

[0056] Step 301: Perform cross-correlation calculation on the two IQ signals;

[0057] One of the two IQ signals, for example, the second IQ signal IQ2(tm), is digitally delayed by dc sampling intervals to obtain the signal IQ2(tm-dc). The signal IQ2(tm-dc) is then delayed left and right by 0 to n sampling intervals (where n can be a positive integer) to obtain the signal sequence IQ2(tm-dc-n), IQ2(tm-dc-n+1), ..., IQ2(tm-dc-1), IQ2(tm-dc), IQ2(tm-dc+1), ..., IQ2(tm-dc+n-1), IQ2(tm-dc+n) (2n+1 signals).

[0058] The other of the two IQ signals, namely the first IQ signal IQ1(tm), is paired with the signal IQ2(tm-dc-k) (k=-n,-n+1,…,n-1,n) in the above signal sequence and cross-correlation is performed to obtain the cross-correlation results χ(dc-n),χ(dc-n+1),……,χ(dc+n-1),χ(dc+n).

[0059] Step 302: Fit the parabolic curve of the cross-correlation function using the multiple delays in the above cross-correlation operation and the amplitude of the cross-correlation operation result corresponding to the delays;

[0060] The cross-correlation function is fitted to a parabolic curve using the delays dc-n, dc-n+1, ​​..., dc+n-1, dc+n and the corresponding amplitudes |χ(dc-n)|, |χ(dc-n+1)|, ..., |χ(dc+n-1)|, |χ(dc+n)|.

[0061] Step 303: Based on the parabolic curve, the delay dm corresponding to the maximum value of the cross-correlation function is obtained by interpolation calculation. The delay dm is multiplied by the sampling interval in the cross-correlation calculation to obtain the accurate TDOA value of the two IQ signals.

[0062] The final accurate TDOA value is obtained by calculating the precise TDOA values ​​of multiple pulse signals within a predetermined time period, filtering the multiple precise TDOA values, and then averaging them.

[0063] Step 400: Calculate the fuzzy phase difference between the two IQ signals, and use the TDOA precise value to defuzzify the fuzzy phase difference to obtain the precise phase difference;

[0064] Find the phase of the cross-correlation result of the two signals, which is the fuzzy phase difference between the two signals, where the first signal is IQ1(tm) and the second signal is IQ2(tm).

[0065] Next, the corresponding phase difference is calculated using the precise value of TDOA, and the ambiguous phase difference is defuzzified to obtain the final correct phase difference; the specific principle of defuzzification is introduced below.

[0066] The phase difference can be obtained from the time delay of the signals received by the two antennas:

[0067]

[0068] Where f is the signal carrier frequency, N is the number of signal samples corresponding to the time delay of the signals received by the two antennas, and dt is the sampling time interval. s The sampling frequency is given. The phase difference can be obtained from the angle of incidence of the signal reaching the two antennas:

[0069]

[0070] Where D is the distance between the two antennas, λ is the signal wavelength, and θ is the angle of incidence. Let K be the phase difference obtained from actual measurement, with a value in the range [0, 360°), and K be the ambiguity number. Theoretically, the phase differences obtained by these two methods are equal, i.e.:

[0071]

[0072] The sample points corresponding to the precise time difference of the signals received by the two antennas can be obtained by using the cross-correlation method. The corresponding measurement error is ΔN, and the measurement error of the phase difference is... but:

[0073]

[0074] When the following conditions are met

[0075]

[0076] The ambiguity number K can be correctly resolved, and thus the correct phase difference can be obtained. As shown in the above equation, when the phase difference measurement error is constant, only by improving the phase difference measurement accuracy through certain methods can the phase difference be correctly resolved. The high-precision phase difference measurement method proposed in this invention is introduced below.

[0077] IQ1(tm) is cross-correlated with IQ1(tm-1), IQ2(tm), and IQ2(tm+1), respectively. Then, the phase corresponding to the cross-correlation result is taken. and This corresponds to the phase difference between the two signals. Due to the ambiguity of the actual measured phase difference, its range is [-π, π). and If three phase differences may experience a 2π jump, and it is determined that the change between two adjacent phase differences exceeds π, phase compensation of ±2π is required for the phase difference. Then, the phase difference after jump processing... and By averaging, a more accurate phase difference measurement value is obtained.

[0078] Using the precise TDOA value calculated above as a guide, the unambiguous value of the phase difference is obtained, that is:

[0079]

[0080] In the formula, The phase difference is an unambiguous value, i.e., the precise phase difference, where Δt is the calculated precise value of TDOA. Let K be the ambiguity value of the phase difference obtained through cross-correlation calculation, and let K be the ambiguity number. The ambiguity number can be calculated using the above formula:

[0081]

[0082] In the formula, round means rounding to the nearest integer.

[0083] Once the ambiguity number K is obtained, the unambiguous phase difference value can be obtained.

[0084] Step 500: Perform linear fitting on the precise phase difference of multiple pulse signals within a predetermined time period, and calculate the slope of the fitted phase difference curve to obtain the phase difference change rate.

[0085] The phase difference of multiple pulses over a period of time (such as one or more radar dwell periods) is calculated, and a linear fit is performed on multiple phase difference values ​​to obtain a more accurate phase difference value. Furthermore, the slope of the fitted phase difference curve, i.e., the rate of change of the phase difference, is calculated.

[0086] This invention utilizes pulse leading-edge detection and subtraction to obtain a coarse time difference between two signals as a guide. Then, it acquires the cross-correlation value corresponding to the time difference between the left and right sides of the coarse time difference, ranging from 0 to n sampling intervals. The cross-correlation results are then curve-fitted, and the time delay corresponding to the maximum cross-correlation value is calculated through interpolation, which is the precise time difference between the two signals. In other words, a coarse time difference is first obtained using the computationally inefficient pulse leading-edge detection method, and then a more accurate correlation method is used to find the maximum and minimum values ​​near the coarse time difference through curve fitting and interpolation to obtain the precise time difference.

[0087] Cross-correlation is performed on the two signals, and the phase of the cross-correlation result is taken as the phase difference between the two signals. The phase difference is then de-ambiguously determined by measuring the time difference of arrival, resulting in a correct, unambiguous, and precise phase difference.

[0088] Finally, a linear fit is performed on the precise phase difference of multiple pulses within the radar dwell time period to further improve the measurement accuracy of the phase difference, and the slope of the fitted phase difference curve is calculated.

[0089] By employing the above method, the present invention overcomes the problems of large computational load, insufficient accuracy, long calculation time, and ambiguity in existing phase difference measurement technologies.

[0090] Figure 3 This is a schematic diagram of a radiation source detection system according to an embodiment of the present invention. As shown in the figure, the system includes an antenna, a receiver, and a signal processor.

[0091] The antenna comprises at least two spatially separated antenna elements. Assume the k-th pulse signal emitted by the target is:

[0092]

[0093] Among them, a[1+a m sin(2πf m n k t s [)] represents amplitude modulation information, t s n is the sampling interval. k =[0,1,2,…,N-1]+(k-1)T / t s .

[0094] The signal received by the first antenna element is:

[0095]

[0096] Where, n 1,k =n k +Δn 1,k ,Δn 1,k =ceil(Δτ) 1,k / t s ).

[0097] The signal received by the second antenna element is:

[0098]

[0099] Where, n 2,k =n k +Δn 2,k ,Δn 2,k =ceil(Δτ) 2,k / t s ).

[0100] The receiver mainly includes an analog down-conversion module, an analog-to-digital converter (ADC) module, a Hilbert transform module, and a filtering module. The analog down-conversion module mixes the at least two RF signals from the antenna with the local oscillator to output an intermediate frequency (IF) signal, reducing the sampling rate of the subsequent ADC. The ADC module receives the IF signal from the analog down-conversion module and performs digital sampling, converting the analog signal into a digital signal. The Hilbert transform module performs a Hilbert transform on the digital IF signal output from the ADC module to obtain the in-phase component I and the vertical component Q, resulting in the complex signal IQ.

[0101] The signal processor includes a phase difference change rate measurement and estimation device, which receives two IQ signals to perform phase difference measurement. Figure 4 This is a schematic diagram of a phase difference change rate measurement and estimation device according to an embodiment of the present invention. As shown in the figure, the device includes:

[0102] The TDOA coarse value calculation unit 401 includes a pulse arrival time detection module and a difference calculation module.

[0103] The pulse arrival time detection module is connected to the receiver output and is used to detect the arrival time of signals radiated from a distant radiation source at the two antennas. This module includes an envelope detection module and a pulse feature detection module. The envelope detection module calculates the envelope of the two pulse signals, i.e., the amplitude of the radio frequency signal received by the antennas; the pulse feature detection module receives the pulse signal amplitude output by the envelope detection module and detects the time corresponding to the pulse feature point, i.e., the pulse arrival time.

[0104] The difference calculation module is connected to the output of the pulse arrival time detection module. It is used to calculate the difference between the arrival times of the above signals at the two antennas, obtain the signal arrival time difference when the two antennas receive the same signal, and obtain a rough TDOA value. The pulse arrival time detection module detects the arrival times of the two signals at the half-amplitude of the pulse envelope corresponding to the rising edge of the pulse, and subtracts the pulse arrival times pairwise to obtain the time difference between the pulse arrival times of the two antennas.

[0105] Since the accuracy of pulse arrival time difference is affected by the accuracy of pulse feature point detection, and the pulse amplitude is easily affected by interference and fluctuates, the feature points based on the pulse amplitude are easily affected by interference. Therefore, the pulse arrival time difference obtained in this process is a rough value of TDOA.

[0106] In another example, the TDOA coarse value calculation unit also includes a statistical filtering module, which averages and filters the TDOA coarse values ​​of multiple pulses over a period of time (such as the radar illumination dwell time) to reduce random measurement and calculation errors.

[0107] The TDOA accurate value calculation unit 402 includes a cross-correlation operation module 4021, a curve fitting module 4022, and an interpolation module 4023.

[0108] The cross-correlation calculation module 4021 is connected to the receiver output and is used to perform cross-correlation calculations on the IQ signals from the two antennas. Specifically, the cross-correlation calculation module is used to perform the following operations:

[0109] Receives two IQ signals from the output of the Hilbert transform module;

[0110] The second IQ signal is delayed left and right by 0 to n sampling intervals (where n can be a positive integer), and the outputs are IQ2(tm-dc-n), IQ2(tm-dc-n+1), ..., IQ2(tm-dc-1), IQ2(tm-dc), IQ2(tm-dc+1), ..., IQ2(tm-dc+n-1), IQ2(tm-dc+n).

[0111] Pair IQ1(tm) with the above IQ2(tm-dc-k) (k=-n,-n+1,……,n-1,n) and perform cross-correlation operation to obtain the cross-correlation operation results χ(dc-n),χ(dc-n+1),……,χ(dc+n-1),χ(dc+n).

[0112] The cross-correlation operation is performed according to the following formula:

[0113]

[0114] The amplitude of the cross-correlation signal is:

[0115]

[0116] The curve fitting module 4022 is connected to the output of the cross-correlation calculation module and is used to perform curve fitting on the 2*n+1 cross-correlation function values ​​output by the cross-correlation calculation module. Specifically, the curve fitting module 4022 uses delays dc-n, dc-n+1, ​​..., dc+n-1, dc+n and the amplitudes |χ(dc-n)|, |χ(dc-n+1)|, ..., |χ(dc+n-1)|, |χ(dc+n)| corresponding to the above delays to fit the parabolic curve of the cross-correlation function, and calculates the delay dm corresponding to the maximum value of the function value through the interpolation module 4023. The delay dm corresponding to the maximum value is the accurate value of TDOA.

[0117] In another example, the TDOA precision value calculation unit also includes a statistical filtering module, which averages and filters the TDOA precision values ​​of multiple pulses over a period of time (such as the radar illumination dwell time) to obtain a more accurate TDOA precision value.

[0118] Traditional measurement schemes require precise measurement of signal time characteristics to obtain target velocity and distance information, and thus the location information of the radiation source. Therefore, traditional schemes are slow and computationally intensive. This invention adds a precise TDOA measurement module. Through cross-correlation calculations, curve fitting, and interpolation calculations in this module, more accurate TDOA measurements can be obtained than with traditional schemes, while significantly reducing computational load and facilitating engineering implementation. It is particularly suitable for airborne electronic countermeasures reconnaissance and warning equipment with high real-time requirements.

[0119] The phase difference calculation unit 403 includes a fuzzy phase difference calculation module 4031 and a defuzzification module 4032.

[0120] The fuzzy phase difference calculation module 4031 is also connected to the output of the cross-correlation operation module. It performs cross-correlation operations on IQ1(tm), IQ1(tm-1), IQ2(tm), and IQ2(tm+1), and then calculates the phase from the cross-correlation results. The result is shown in the following formula:

[0121]

[0122] This yields the phase difference between the two signals. However, the phase difference obtained directly in this process is ambiguous, with a range of [-π, π). and If three phase differences may experience a 2π jump, and it is determined that the change between two adjacent phase differences exceeds π, phase compensation of ±2π is required for the phase difference. Then, the phase difference after jump processing... and By averaging, a more accurate phase difference measurement value is obtained.

[0123] The defuzzing module 4032 is connected to the TDOA accurate value calculation unit 402 and the fuzzy phase difference calculation module 4031 respectively, and uses the TDOA accurate value to calculate the defuzzing value of the phase difference.

[0124] Specifically, the defuzzified value of the fuzzy phase difference is obtained by using the precise TDOA value calculated above as a guide:

[0125]

[0126] In the formula, The phase difference is an unambiguous value, i.e., the precise phase difference, where Δt is the calculated precise value of TDOA. Let K be the ambiguity value of the phase difference obtained through cross-correlation calculation, and let K be the ambiguity number. The ambiguity number can be calculated using the above formula:

[0127]

[0128] In the formula, round means rounding to the nearest integer.

[0129] After calculating the blur number K, the unambiguous phase difference value can be obtained.

[0130] Therefore, after obtaining the accurate TDOA value, under certain conditions, the phase difference defuzzification unit can calculate the fuzziness number and obtain an accurate phase difference without fuzziness.

[0131] The phase difference change rate calculation unit 404 is used to perform linear fitting on the precise phase difference of multiple pulse signals within a predetermined time period, and calculate the slope of the fitted phase difference curve to obtain the phase difference change rate.

[0132] The phase difference change rate calculation unit 404 performs linear fitting on the phase difference of multiple pulses within a certain period of time (the radar illumination dwell time) to obtain a more accurate phase difference, and calculates the slope of the fitted phase difference curve to obtain the phase difference change rate.

[0133] This invention obtains the phase difference change rate through cross-correlation calculation and linear fitting unit. Compared with traditional measurement schemes that can only obtain the phase difference change rate from the phase difference between consecutive time points, the phase difference change rate obtained by this invention has higher accuracy.

[0134] Example 1:

[0135] like Figure 1As shown, signal reception is achieved using a dual-antenna, dual-channel configuration with an antenna spacing of 10 meters and an antenna normal installation angle of 0 degrees on the positioning station. The AD sampling frequency is 1.25 GHz, and the AD sampling point width is 10 bits. The signal-to-noise ratio is 20 dB, the carrier frequency is 1.32 GHz, the signal pulse width is 0.5 μs, the pulse repetition interval is 2 ms, and the amplitude modulation characteristic of the signal envelope is 3 MHz / 0.03. The initial azimuth angle of the target is 60 degrees, the initial distance between the positioning station and the target is 200 km, the positioning station's speed is 200 m / s, and the direction is due north. A total of 50 pulses are generated. Figure 5 , Figure 6 This is a schematic diagram illustrating the trend of phase difference variation and the accuracy of phase difference measurement.

[0136] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring and estimating the rate of change of phase difference, characterized in that, include: Acquire two IQ signals from the same pulse signal from the radiation source; Calculate the arrival time difference between the two IQ signals to obtain a rough TDOA value; Cross-correlation is performed on the two IQ signals. Based on the cross-correlation result, curve fitting is performed near the coordinate point corresponding to the rough value of TDOA, and the precise value of TDOA is calculated based on the fitted curve. Calculate the ambiguous phase difference between the two IQ signals, and use the precise TDOA value to deambiguate the ambiguous phase difference to obtain the precise phase difference; Linear fitting is performed on the precise phase difference of multiple pulse signals within a predetermined time period, and the slope of the fitted phase difference curve is calculated to obtain the phase difference change rate. The step of performing cross-correlation on the two IQ signals, and then performing curve fitting near the coordinate points corresponding to the approximate TDOA value based on the cross-correlation result, to calculate the precise TDOA value based on the fitted curve, includes: Perform cross-correlation calculation on the two IQ signals; The parabolic curve of the cross-correlation function is fitted using the multiple delays in the above cross-correlation operation and the magnitude of the cross-correlation operation results corresponding to the delays; Based on the parabolic curve, the delay corresponding to the maximum value of the cross-correlation function is obtained by interpolation calculation. The delay is then multiplied by the sampling interval in the cross-correlation operation to obtain the precise TDOA value of the two IQ signals.

2. The method for measuring and estimating the rate of change of phase difference according to claim 1, characterized in that, The step of using the precise TDOA value to deblur the fuzzy phase difference to obtain the precise phase difference includes: Calculate fuzzy numbers K ; The unambiguous phase difference value is calculated using the following formula: In the formula, This is the fuzzy phase difference obtained through cross-correlation calculation.

3. The method for measuring and estimating the rate of change of phase difference according to claim 1 or 2, characterized in that, The predetermined time period is one or more radar dwell cycles.

4. A method for measuring and estimating the rate of change of phase difference, characterized in that, include: Obtain the rough time difference of arrival of the two IQ signals; The cross-correlation results corresponding to the time differences between the coarse and fine IQ signals, which are several sampling intervals apart, are obtained. Curve fitting is performed on the cross-correlation results, and the delay corresponding to the maximum cross-correlation value is calculated by interpolation as the fine-measured time difference between the two IQ signals. Specifically, a parabolic curve of the cross-correlation function is fitted using multiple delays in the cross-correlation calculation and the amplitude of the cross-correlation results corresponding to these delays. Based on the parabolic curve, the delay corresponding to the maximum cross-correlation function value is calculated using interpolation. Cross-correlation calculation is performed on the two IQ signals, and the phase of the cross-correlation calculation result is taken as the fuzzy phase difference between the two IQ signals. The fuzzy phase difference is then defuzzified using the precise time difference of arrival to obtain a fuzzy and accurate phase difference. Linear fitting is performed on the precise phase difference of multiple pulse signals within a predetermined time period, and the slope of the fitted phase difference curve is calculated to obtain the phase difference change rate.

5. The method for measuring and estimating the rate of change of phase difference according to claim 4, characterized in that, The predetermined time period is one or more radar dwell cycles.

6. A device for measuring and estimating the rate of change of phase difference, characterized in that, include: The TDOA coarse value calculation unit is used to obtain the coarse arrival time difference between the two IQ signals; The TDOA precision value calculation unit is used to obtain the cross-correlation calculation results corresponding to the time differences between the coarse and fine IQ signals, which are separated by several sampling intervals. The cross-correlation calculation results are then curve-fitted, and the delay corresponding to the maximum cross-correlation value is calculated by interpolation as the precision arrival time difference between the two IQ signals. Specifically, a parabolic curve of the cross-correlation function is fitted using multiple delays in the cross-correlation calculation and the amplitude of the cross-correlation calculation results corresponding to these delays. Based on the parabolic curve, the delay corresponding to the maximum cross-correlation function value is calculated using interpolation. A phase difference calculation unit is used to perform cross-correlation calculation on two IQ signals, take the phase of the cross-correlation calculation result as the fuzzy phase difference between the two IQ signals, and use the precise time difference of arrival to defuzzify the fuzzy phase difference to obtain an unfuzzy, precise phase difference; and The phase difference change rate calculation unit is used to perform linear fitting on the precise phase difference of multiple pulse signals within a predetermined time period, and calculate the slope of the fitted phase difference curve to obtain the phase difference change rate.

7. The phase difference change rate measurement and estimation device according to claim 6, characterized in that, The predetermined time period is one or more radar dwell cycles.

8. The phase difference change rate measurement and estimation device according to claim 6, characterized in that, The phase difference calculation unit calculates the fuzzy number. K And calculate the unambiguous phase difference value according to the following formula: In the formula, This is the fuzzy phase difference obtained through cross-correlation calculation.

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