An Interferometer Direction Finding Deambiguity Method under Low Signal-to-Noise Ratio

Abstract

The present invention discloses an interferometer direction finding deambiguation method under low signal-to-noise ratio, comprising obtaining N actual baselines, and obtaining M virtual baselines from the virtual baselines formed by the N actual baselines; for any obtained virtual baseline: taking the virtual baseline as a reference, obtaining the phase difference and baseline length of the virtual baseline of the reference and all actual baselines, and obtaining the ambiguity number of all actual baselines. The interferometer direction finding deambiguation method under low signal-to-noise ratio utilizes the phase difference measurement value of each virtual baseline to decouple and perform deambiguation processing respectively, rather than treating the phase difference of each baseline as a whole for step-by-step deambiguation, which can effectively improve the probability of correct deambiguation; it can reduce the requirement of the interferometer direction finding on the signal-to-noise ratio, and can also achieve a higher probability of correct deambiguation when the signal-to-noise ratio is low.

Description

Technical Field

[0001] The invention belongs to the technical field of interferometer direction finding and deambiguation, and in particular relates to an interferometer direction finding and deambiguation method under low signal-to-noise ratio. Background Art

[0002] In passive signal reconnaissance, the direction of arrival (DOA) is a very important parameter. Accordingly, the technology for estimating it is called direction finding technology. At present, the commonly used direction finding methods in the industry mainly include amplitude comparison direction finding, time difference direction finding, Doppler direction finding, spatial spectrum estimation direction finding, phase comparison direction finding, interferometer direction finding, etc. Since interferometer direction finding technology is fast, accurate, and easy to implement in FPGA, it has become the most practical and important one among many direction finding technologies, and is widely used in military and civilian fields such as radar, communication, and measurement and control technology.

[0003] The existing interferometer direction finding deambiguation processing technology based on multi-level virtual baselines uses the phase difference of multi-level virtual baselines to deambiguate step by step, that is, the phase difference of each baseline is treated as a whole and deambiguated step by step. However, the correctness of this process is closely related to the signal-to-noise ratio. Since the length of the virtual baseline is small, its true phase difference value is small, and the measurement result is greatly affected by the signal-to-noise ratio. The estimation error caused by this recursion will be multiplied, resulting in a large direction finding error. When the measurement error of one level of phase difference is large, it will directly affect the deambiguation result, resulting in a large error in the direction finding result. This phenomenon is particularly obvious under low signal-to-noise ratio conditions. Therefore, it is necessary to study the deambiguation processing technology under low signal-to-noise ratio to meet the needs of processing low signal-to-noise ratio signals in actual reconnaissance processes. Summary of the invention

[0004] The purpose of the present invention is to solve the problem raised in the background technology and to propose an interferometer direction finding deambiguation method under low signal-to-noise ratio.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention proposes an interferometer direction finding deambiguation method under low signal-to-noise ratio, comprising: obtaining The actual baseline, and the The virtual baseline is obtained from the actual baselines. A virtual baseline;

[0007] For any virtual baseline obtained: taking the virtual baseline as the reference, obtain the phase difference and baseline length of the virtual baseline of the reference and all the actual baselines, and obtain the fuzzy numbers of all the actual baselines;

[0008] According to the ambiguity number and phase difference of the actual baseline, the first unambiguous phase difference of each actual baseline is obtained;

[0009] According to the fact that the unambiguous phase difference of each baseline is proportional to the length of the baseline, as well as the phase difference and length of the virtual baseline of the reference and the length of the actual baseline, the second unambiguous phase difference of each actual baseline is obtained;

[0010] The deviations of the first unambiguous phase differences corresponding to all actual baselines relative to the second unambiguous phase differences are accumulated to obtain a relative deviation sum, and then the first unambiguous phase differences corresponding to the minimum relative deviation sum are used as the unambiguous phase differences of each actual baseline.

[0011] Preferably, Virtual baselines are used to collect Indicates that The actual baseline is used as a set Indicated, and the length of each baseline satisfies the following relationship:

[0012] ;

[0013] in, Indicates The length of the virtual baseline of the benchmark, Indicates The actual baseline length.

[0014] Preferably, taking the virtual baseline as a reference, obtaining the phase difference and baseline length between the virtual baseline of the reference and all actual baselines, and obtaining the fuzzy numbers of all actual baselines, comprises:

[0015] For any virtual baseline of a benchmark, the virtual baseline of the benchmark and Actual baseline according to are numbered in order, and The number of the virtual baseline representing the benchmark, Sequentially indicate The number of the actual baseline;

[0016] The phase difference between the virtual baseline and all actual baselines is unified by Represents, and the expression is as follows:

[0017] , ;

[0018] in, Indicates The phase difference of the virtual baseline of the reference, Indicates The phase difference of the actual baseline;

[0019] The virtual baseline and all actual baseline lengths of the benchmark are unified as Represents, and the expression is as follows:

[0020] , ;

[0021] The fuzzy numbers of the virtual baseline and all actual baselines are unified using It is expressed as follows:

[0022] ;

[0023] Among them, when When is the fuzzy number of the virtual baseline of the benchmark, and is 0, Indicates the number The actual baseline phase difference is Indicates the number The phase difference of the baseline, Indicates the number The actual baseline length, Indicates the number The length of the baseline, Indicates the number The fuzzy number of the baseline.

[0024] Preferably, the calculation formula of the first unambiguous phase difference is as follows:

[0025] , ;

[0026] in, Indicates the The virtual baseline is used as the benchmark. The first unambiguous phase difference of the actual baseline, Indicates The actual baseline phase difference, Indicates the number for The fuzzy number of the actual baseline;

[0027] Then take the The first unambiguous phase difference of all actual baselines is the set of .

[0028] Preferably, the calculation formula of the second unambiguous phase difference is as follows:

[0029] , ;

[0030] in, Indicates the The virtual baseline is used as the benchmark. The second unambiguous phase difference of the actual baseline, Indicates The length of the virtual baseline of the benchmark, Indicates The actual baseline length, Indicates The phase difference of the virtual baseline of the reference;

[0031] Then take the The set of the second unambiguous phase differences of all actual baselines is .

[0032] Preferably, the step of accumulating the deviations of the first unambiguous phase differences corresponding to all actual baselines relative to the second unambiguous phase differences to obtain a relative deviation sum, and then taking the first unambiguous phase differences corresponding to the minimum relative deviation sum as the unambiguous phase differences of each actual baseline, comprises:

[0033] The deviations of the first unambiguous phase difference corresponding to all actual baselines relative to the second unambiguous phase difference are accumulated to obtain a relative deviation sum, and the calculation formula of the relative deviation sum is as follows:

[0034] ;

[0035] in, Indicates the The virtual baseline is used as the reference, and the relative deviation of all actual baselines is summed;

[0036] for virtual baseline, we get The minimum relative deviation and the corresponding first unambiguous phase difference are taken as the unambiguous phase difference of each actual baseline.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The interferometer direction finding deambiguation method under low signal-to-noise ratio utilizes the phase difference measurement values ​​of each virtual baseline to decouple and perform deambiguation processing separately, rather than treating the phase difference of each baseline as a whole and deambiguating it step by step. This can effectively improve the probability of correct deambiguation; it can reduce the requirements of the interferometer direction finding on the signal-to-noise ratio, and can achieve a higher probability of correct deambiguation when the signal-to-noise ratio is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of the interferometer direction finding deambiguation method under low signal-to-noise ratio of the present invention;

[0040] Figure 2The one-dimensional interferometer antenna array in the embodiment of the present invention;

[0041] Figure 3 Schematic diagram showing the comparison of the correct deambiguation probability between the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 5 dB;

[0042] Figure 4 Schematic diagram showing the comparison of the correct deambiguation probability between the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 6 dB;

[0043] Figure 5 It is a schematic diagram comparing the correct deambiguation probability of the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 7dB;

[0044] Figure 6 Schematic diagram showing the comparison of the correct deambiguation probability between the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 8 dB;

[0045] Figure 7 It is a schematic diagram showing the comparison of the correct deambiguation probability between the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 9 dB;

[0046] Figure 8 It is a schematic diagram showing the comparison of the correct deambiguation probability between the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 10 dB;

[0047] Fig. 9 It is a schematic diagram comparing the correct deambiguation probability of the method proposed by the present invention and the traditional method when the signal-to-noise ratio is 11dB;

[0048] Fig.10 It is a schematic diagram comparing the correct deambiguation probability of the method proposed in the present invention and the traditional method when the signal-to-noise ratio is 12dB. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0050] like Figure 1-Figure 2 As shown, an interferometer direction finding deambiguation method under low signal-to-noise ratio is provided, including (first, the terms are explained as follows: baseline: an antenna pair consisting of two antenna array elements; actual baseline: a baseline composed of two actually existing antenna array elements; virtual baseline: a baseline that does not actually exist constructed by performing sum and difference operations on two actual baselines):

[0051] S1. Acquisition The actual baseline, and the The virtual baseline is obtained from the actual baselines. A virtual baseline;

[0052] It should be noted that, in this embodiment, Figure 2 As shown, the one-dimensional interferometer antenna array is For example, if the antenna composition is The actual baseline Antennas can be constructed virtual baselines, where the maximum number of virtual baselines is There is no restriction on the specific data used. It can be set according to actual needs. Virtual baselines are used to collect Indicates that The actual baseline is used as a set Indicated, and the length of each baseline satisfies the following relationship:

[0053] ;

[0054] in, Indicates The length of the virtual baseline of the benchmark, Indicates The length of the actual baseline; Respectively represent the length of the virtual baseline, Respectively represent the length of the actual baseline; Figure 2 The imaginary elements in represent virtual antennas. Angle represents the incident angle of the radiation source signal.

[0055] S2. For any virtual baseline obtained: taking the virtual baseline as a reference, obtain the phase difference and baseline length of the virtual baseline of the reference and all actual baselines (that is, obtain the phase difference and baseline length of the virtual baseline of the reference, and obtain the phase difference and baseline length of all actual baselines), and obtain the fuzzy numbers of all actual baselines, specifically including:

[0056] For any virtual baseline of a benchmark, the virtual baseline of the benchmark and Actual baseline according to are numbered in order, and The number of the virtual baseline representing the benchmark, Sequentially indicate The number of the actual baseline;

[0057] The phase difference between the virtual baseline and all actual baselines is unified by Represents, and the expression is as follows:

[0058] , ;

[0059] in, Indicates The phase difference of the virtual baseline of the reference, Indicates It should be noted that the specific process of obtaining the phase difference of the virtual baseline and the phase difference of the actual baseline belongs to the prior art, and the specific process will not be elaborated in detail.

[0060] The virtual baseline and all actual baseline lengths of the benchmark are unified as Represents, and the expression is as follows:

[0061] , ;

[0062] in, Indicates The length of the virtual baseline of the benchmark, Indicates The length of the actual baseline;

[0063] The fuzzy numbers of the virtual baseline and all actual baselines are unified using It is expressed as follows:

[0064] ;

[0065] Among them, when When , the fuzzy number of the virtual baseline of the reference is 0 (because the phase difference of each virtual baseline is unambiguous, the fuzzy number of each virtual baseline is 0, which belongs to the prior art), Indicates the number The actual baseline phase difference is Indicates the number The phase difference of the baseline (when When the value of is 2, is the phase difference of the virtual baseline, when Greater than 2, then is the phase difference of the actual baseline), Indicates the number The actual baseline length, Indicates the number The length of the baseline (when When the value of is 2, is the length of the virtual baseline, when Greater than 2, then is the actual baseline length), Indicates the number The fuzzy number of the baseline (when When the value of is 2, is the fuzzy number of the virtual baseline, when Greater than 2, then is the fuzzy number of the actual baseline).

[0066] S3. According to the fuzzy number and phase difference of the actual baseline, the first unambiguous phase difference of each actual baseline is obtained, and the calculation formula of the first unambiguous phase difference is as follows:

[0067] , ;

[0068] in, Indicates the The virtual baseline is used as the benchmark. The first unambiguous phase difference of the actual baseline, Indicates The actual baseline phase difference, Indicates the number for The fuzzy number of the actual baseline;

[0069] Then take the The first unambiguous phase difference of all actual baselines is the set of .

[0070] S4. According to the unambiguous phase difference of each baseline being proportional to the baseline length, as well as the phase difference and length of the virtual baseline of the reference and the length of the actual baseline, the second unambiguous phase difference of each actual baseline is obtained, and the calculation formula of the second unambiguous phase difference is as follows:

[0071] , ;

[0072] in, Indicates the The virtual baseline is used as the benchmark. The second unambiguous phase difference of the actual baseline, Indicates The length of the virtual baseline of the benchmark, Indicates The actual baseline length, Indicates The phase difference of the virtual baseline of the reference;

[0073] Then take the The set of the second unambiguous phase differences of all actual baselines is .

[0074] S5, accumulating the deviations of the first unambiguous phase differences corresponding to all actual baselines relative to the second unambiguous phase differences to obtain a relative deviation sum, and then taking the minimum relative deviation sum and the corresponding first unambiguous phase differences as the unambiguous phase differences of each actual baseline, specifically including:

[0075] The deviations of the first unambiguous phase difference corresponding to all actual baselines relative to the second unambiguous phase difference are accumulated to obtain a relative deviation sum, and the calculation formula of the relative deviation sum is as follows:

[0076] ;

[0077] in, Indicates the The virtual baseline is used as the reference, and the relative deviation of all actual baselines is summed;

[0078] for virtual baseline, we get The relative deviation and (based on the virtual baseline As a benchmark, follow the steps S1-S5 to obtain the corresponding relative deviation and, then use the virtual baseline As a benchmark, follow the steps S1-S5 to obtain the corresponding relative deviation and, and so on, to obtain the virtual baseline. The corresponding relative deviation and, that is, relative deviations and), taking the minimum relative deviation and the corresponding first unambiguous phase difference as the unambiguous phase difference of each actual baseline.

[0079] The unambiguous phase difference corresponding to the longest actual baseline among the unambiguous phase differences of the actual baselines calculated can be used to calculate the incident angle of the radiation source signal using the following formula: :

[0080] ;

[0081] in, represents the signal wavelength, represents the length of the longest actual baseline, Indicates the unambiguous phase difference corresponding to the longest actual baseline.

[0082] The number of antennas and the antenna spacing in the interferometer direction finding system need to be designed according to specific system indicators, which is not discussed in this application. Here is only a specific example:

[0083] A one-dimensional four-baseline interferometer direction-finding system consisting of five antennas, the actual baseline lengths are , the number of virtual baselines is selected as 4, and their construction methods and lengths are .

[0084] The incident angle of the radiation source signal is calculated using the phase difference after deambiguation. , when the angle If the difference from the true angle is less than a threshold (e.g., 2°), the deblurring is considered correct.

[0085] When the input signal frequency is 2.4GHz and the direction finding range is (That is, the incident angle is ), when the signal-to-noise ratio is 5~12dB, 1000 simulations are performed under each set of parameters. The correct defuzzification probability comparison between the proposed method and the traditional method is as follows: Figure 3-Figure 10 As shown, it can be seen from the accompanying drawings that: when the signal-to-noise ratio is between 5 and 10 dB (under low signal-to-noise ratio), the probability of correct deambiguation is significantly improved; for the method proposed in this application, when the signal-to-noise ratio is greater than or equal to 8 dB, more than 75% of the incident angle values ​​can achieve a 99% correct deambiguation probability; in contrast, in order to achieve a 99% correct deambiguation probability, the traditional method requires a signal-to-noise ratio greater than or equal to 11 dB.

[0086] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0087] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An interferometer direction finding deambiguation method under low signal-to-noise ratio, characterized in that: The interferometer direction finding deambiguation method under low signal-to-noise ratio comprises: Get The actual baseline, and the The virtual baseline is obtained from the actual baselines. A virtual baseline; For any virtual baseline obtained: taking the virtual baseline as the reference, obtain the phase difference and baseline length of the virtual baseline of the reference and all the actual baselines, and obtain the fuzzy numbers of all the actual baselines; According to the ambiguity number and phase difference of the actual baseline, the first unambiguous phase difference of each actual baseline is obtained; According to the fact that the unambiguous phase difference of each baseline is proportional to the length of the baseline, as well as the phase difference and length of the virtual baseline of the reference and the length of the actual baseline, the second unambiguous phase difference of each actual baseline is obtained; The deviations of the first unambiguous phase differences corresponding to all actual baselines relative to the second unambiguous phase differences are accumulated to obtain a relative deviation sum, and then the first unambiguous phase differences corresponding to the minimum relative deviation sum are used as the unambiguous phase differences of each actual baseline.

2. The interferometer direction finding deambiguation method under low signal-to-noise ratio as claimed in claim 1, characterized in that: Will Virtual baselines are used to collect Indicates that The actual baseline is used as a set Indicated, and the length of each baseline satisfies the following relationship: ； in, Indicates The length of the virtual baseline of the benchmark, Indicates The actual baseline length.

3. The interferometer direction finding deambiguation method under low signal-to-noise ratio as claimed in claim 2, characterized in that: The method of taking the virtual baseline as a reference, obtaining the phase difference and baseline length between the virtual baseline of the reference and all actual baselines, and obtaining the fuzzy numbers of all actual baselines includes: For any virtual baseline of a benchmark, the virtual baseline of the benchmark and Actual baseline according to are numbered in order, and The number of the virtual baseline representing the benchmark, Sequentially indicate The number of the actual baseline; The phase difference between the virtual baseline and all actual baselines is unified by Represents, and the expression is as follows: ， ； in, Indicates The phase difference of the virtual baseline of the reference, Indicates The phase difference of the actual baseline; The virtual baseline and all actual baseline lengths of the benchmark are unified as Represents, and the expression is as follows: ， ； The fuzzy numbers of the virtual baseline and all actual baselines are unified using It is expressed as follows: ； Among them, when When is the fuzzy number of the virtual baseline of the benchmark, and is 0, Indicates the number The actual baseline phase difference, Indicates the number The phase difference of the baseline, Indicates the number The actual baseline length, Indicates the number The length of the baseline, Indicates the number The fuzzy number of the baseline.

4. The interferometer direction finding deambiguation method under low signal-to-noise ratio as claimed in claim 2, characterized in that: The calculation formula of the first unambiguous phase difference is as follows: ， ； in, Indicates the The virtual baseline is used as the benchmark. The first unambiguous phase difference of the actual baseline, Indicates The actual baseline phase difference, Indicates the number for The fuzzy number of the actual baseline; Then take the The first unambiguous phase difference of all actual baselines is the set of .

5. The interferometer direction finding deambiguation method under low signal-to-noise ratio as claimed in claim 4, characterized in that: The calculation formula of the second unambiguous phase difference is as follows: ， ； in, Indicates the The virtual baseline is used as the benchmark. The second unambiguous phase difference of the actual baseline, Indicates The length of the virtual baseline of the benchmark, Indicates The actual baseline length, Indicates The phase difference of the virtual baseline of the reference; Then take the The set of the second unambiguous phase differences of all actual baselines is .

6. The interferometer direction finding deambiguation method under low signal-to-noise ratio as claimed in claim 5, characterized in that: The deviations of the first unambiguous phase differences corresponding to all actual baselines relative to the second unambiguous phase differences are accumulated to obtain a relative deviation sum, and then the first unambiguous phase differences corresponding to the minimum relative deviation sum are used as the unambiguous phase differences of each actual baseline. include: The deviations of the first unambiguous phase difference corresponding to all actual baselines relative to the second unambiguous phase difference are accumulated to obtain a relative deviation sum, and the calculation formula of the relative deviation sum is as follows: ； in, Indicates the The virtual baseline is used as the reference, and the relative deviation of all actual baselines is summed; for virtual baseline, we get The minimum relative deviation and the corresponding first unambiguous phase difference are taken as the unambiguous phase difference of each actual baseline.

Images