Robust phase difference jump correction method for uniform circular array interferometer

Abstract

The invention discloses a robust phase difference jump correction method for a uniform circular array interferometer, belongs to the technical field of direction finding of a motion platform interferometer, and aims to solve the problems that in engineering application in the prior art, threshold setting is not flexible, consideration is not comprehensive enough, and operation redundancy is large. According to the method, a judgment threshold that part of measured values jump and all measured values jump in a phase difference sequence is demonstrated, jump correction and fuzzy number range adjustment are carried out according to the threshold for different conditions, and finally the judgment threshold is sent to an interferometer defuzzification direction finding process. The method is rigorous in demonstration, the judgment threshold of + / -pi jump of part of measured values in the phase difference sequence is defined, and a theoretical basis is provided. The method is complete in design, and the situation that all phase difference sequences possibly jump in the application of the motion platform is considered. According to the method, operation is efficient, the situation that the fuzzy number search range needs to be widened is reasonably judged, and waste of hardware resources is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of motion platform interferometer direction finding, and in particular relates to a robust uniform circular array interferometer phase difference jump correction method. Background Art

[0002] Uniform circular array interferometers are widely used in motion platforms because of their strong real-time performance and ability to cover wide-band signals. Interferometer direction finding must first obtain phase difference measurements. In order to reduce the impact of noise on measurement errors, multiple instantaneous measurements are usually averaged in engineering. However, phase difference measurements are more likely to have ±π jumps at the boundaries of the main value interval, which results in an increase in error after averaging multiple measurements or even unambiguity failure. Therefore, before unambiguous direction finding, the phase difference jumps of multiple measurements must be corrected.

[0003] In the prior art, the decision threshold is first used to detect the sequence of measured values ​​that have jumped, then all phase differences less than 0 are averaged with 2π, and finally the average value is transformed into the phase main value interval to complete the phase difference jump correction. However, in engineering practice, the above method has the following problems: 1) The decision threshold for the jump is selected rather arbitrarily, and no basis for selection is given; 2) Only the situation where part of the phase difference measurement value sequence has jumped and the other part has not jumped is considered, while the real-time requirements of the motion platform are high and the number of measurements involved in the average is small, and there are also situations where all jumps occur and need to be judged and processed; 3) In order to be compatible with the possible extra 2π period ambiguity in the jump correction operation, the maximum integer K of the absolute value of the fuzzy number is uniformly relaxed to K+1 for all situations. For example, if the fuzzy number range is [-2,2] when no jump occurs, after relaxing it to [-3,3], the number of defuzzification traversal attempts for all situations is increased from 5 to 1. 2 Increase to 7 2 , while the phase difference jump only occurs under special conditions, which makes the system calculation amount redundant and leads to unnecessary waste of hardware resources.

[0004] Therefore, at this stage, it is necessary to design a robust uniform circular array interferometer phase difference jump correction method, system and storage medium to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a robust uniform circular array interferometer phase difference jump correction method, system and storage medium, which are used to solve the technical problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A robust uniform circular array interferometer phase difference jump correction method comprises the following steps:

[0008] S1: According to the circular array parameters and the received signal frequency, calculate the maximum integer K of the absolute value of the phase difference ambiguity number under the condition that no jump occurs;

[0009] S2: Determine the decision threshold for a portion of the measured values ​​in the phase difference sequence measured multiple times to have a ±π jump as Th1 = π;

[0010] S3: According to the phase difference measurement accuracy σ φ and the number of measurements N, the decision threshold for all measured values ​​in the phase difference sequence of multiple measurements to jump is determined as

[0011] S4: According to the decision thresholds Th1 and Th2, the phase difference jump correction and the maximum integer K of the absolute value of the fuzzy number are adjusted according to different situations;

[0012] S5: Perform the operation of step S4 on the multiple measured phase difference sequences of all baselines used for interferometer deambiguation and direction finding, and obtain the average phase difference φ of all baselines after the jump correction is completed. out and the adjusted K respectively, take the maximum value of these K as the maximum integer of the absolute value of the phase difference ambiguity number, and take the average phase difference φ of all baselines out The maximum K value is sent to the interferometer deambiguation direction finding process to complete the phase difference jump correction.

[0013] Furthermore, in step S2, the decision threshold is determined based on:

[0014] Assume that the true value of the phase difference is φ and the phase difference measurement accuracy is σ φ , and the error follows a normal distribution, then the phase difference measurement value is in the range [φ-4σ φ ,φ+4σ φ ] has a probability of being within the interval of 99.9937%. Statistically, the difference between the maximum and minimum values ​​in the phase difference sequence measured multiple times has the following three possibilities:

[0015] 1) If the phase difference measurement value sequence does not jump at all or all jumps, the maximum difference is 8σ φ ;

[0016] 2) If some of the measured values ​​jump from near -π to near π, in extreme cases φ-4σ φ Jump to φ-4σ φ +2π, then the minimum difference is 2π-8σ φ ;

[0017] 3) If some of the measured values ​​jump from near π to near -π, in extreme cases φ+4σ φ Jump to φ+4σ φ -2π, then the minimum difference is 2π-8σφ ;

[0018] In order to distinguish the first possibility from the latter two possibilities, the difference between the maximum and minimum values ​​in the phase difference sequence is selected as the decision metric. φ <π / 8, choose 8σ φ and 2π-8σ φ The average value π of is used as the decision threshold to achieve the best distinction effect.

[0019] Further, in step S3, the principle of 4 times is the same as step S2, divided by This is because the accuracy of N-time averaging is improved. If the average value of multiple measurements is If the measured values ​​are in the interval [-π, -π+Th2] or [π-Th2, π], it is considered that all measured values ​​have jumped.

[0020] Further, step S4 is specifically as follows:

[0021] 1) Search for the maximum and minimum values ​​of the phase difference sequence measured multiple times and calculate their difference;

[0022] 2) If the difference is greater than Th1, perform the following processing:

[0023] a) Add 2π to all phase differences less than 0 in the sequence, and then calculate the average value of the sequence

[0024] b) Transformed to Make it within the phase principal value interval (-π, π], where mod(·) is the remainder with respect to 2π;

[0025] c) Increase the maximum integer of the absolute value of the fuzzy number by 1, that is, K = K + 1;

[0026] 3) If the difference is less than or equal to Th1, perform the following processing:

[0027] a) Find the average value of the sequence

[0028] b) If φ out If it is in the interval [-π, -π+Th2] or [π-Th2, π], increase the maximum integer of the absolute value of the fuzzy number by 1, that is, K=K+1, otherwise the value of K remains unchanged.

[0029] A robust uniform circular array interferometer phase difference jump correction system adopts the above-mentioned robust uniform circular array interferometer phase difference jump correction method to perform uniform circular array interferometer phase difference jump correction.

[0030] A storage medium stores a computer program, and when the computer program is run, the computer program executes the above-mentioned robust uniform circular array interferometer phase difference jump correction method.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The method of the present invention is rigorously demonstrated, clarifies the decision threshold for ±π jumps in some measured values ​​in the phase difference sequence, and provides a theoretical basis.

[0033] 2. The method of the present invention is well designed, taking into account the situation where all phase difference sequences that may exist in motion platform applications jump.

[0034] 3. The method of the present invention is efficient in operation and can reasonably determine the situation where the fuzzy number search range needs to be relaxed, thus avoiding the waste of hardware resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The flowchart of the implementation of the robust uniform circular array interferometer phase difference jump correction method.

[0036] Figure 2 The present invention is a flowchart for implementing phase difference jump correction and adjustment of the maximum integer K of the absolute value of the fuzzy number according to different situations.

[0037] Figure 3 Schematic diagrams of three possible differences between the maximum and minimum values ​​in a phase difference sequence measured multiple times.

[0038] Figure 4 This is the case where the phase difference sequence obtained by 16 measurements provided in the embodiment of the present invention does not jump.

[0039] Figure 5 This is the case where all phase difference sequences obtained through 16 measurements provided in the embodiment of the present invention undergo jumps.

[0040] Figure 6 This is the case where some measurement values ​​of the phase difference sequence obtained by 16 measurements provided by the embodiment of the present invention jump and the average value calculated after the negative phase is supplemented by 2π is near π.

[0041] Figure 7 This is the case where some measurement values ​​of the phase difference sequence obtained by 16 measurements provided by the embodiment of the present invention jump and the average value calculated after the negative phase is supplemented by 2π is near -π. DETAILED DESCRIPTION

[0042] Embodiment 1:

[0043] A robust uniform circular array interferometer phase difference jump correction method comprises the following steps:

[0044] S1: According to the circular array parameters and the received signal frequency, calculate the maximum integer K of the absolute value of the phase difference ambiguity number under the condition that no jump occurs;

[0045] S2: Determine the decision threshold for a portion of the measured values ​​in the phase difference sequence measured multiple times to have a ±π jump as Th1 = π;

[0046] S3: According to the phase difference measurement accuracy σ φ and the number of measurements N, the decision threshold for all measured values ​​in the phase difference sequence of multiple measurements to jump is determined as

[0047] S4: According to the decision thresholds Th1 and Th2, the phase difference jump correction and the maximum integer K of the absolute value of the fuzzy number are adjusted according to different situations;

[0048] S5: Perform the operation of step S4 on the multiple measured phase difference sequences of all baselines used for interferometer deambiguation and direction finding, and obtain the average phase difference φ of all baselines after the jump correction is completed. out and the adjusted K respectively, take the maximum value of these K as the maximum integer of the absolute value of the phase difference ambiguity number, and take the average phase difference φ of all baselines out The maximum K value is sent to the interferometer deambiguation direction finding process to complete the phase difference jump correction.

[0049] Embodiment 2:

[0050] Take the test parameters of a radar seeker as an example. Seven array elements are evenly distributed on a circle with a radius r of 120 mm. The direction finding frequency range is 2 GHz to 18 GHz (the wavelength λ range is 16.7 mm to 150 mm). The incident signal azimuth angle α∈[0, 2π], the elevation angle β∈[π / 6, π], and the phase difference measurement accuracy σ φ is 15° and the number of measurements N is 16.

[0051] The incident signal frequency to be measured is 8.2 GHz, the azimuth angle α is 115°, and the elevation angle β is 30°. At this time, the noisy phase difference sequence of multiple measurements of each baseline has been obtained. Before performing ambiguity resolution and direction finding, the robust phase difference jump correction method is implemented as follows:

[0052] Step 1: According to the circular array parameters and the received signal frequency, calculate the maximum integer of the absolute value of the phase difference ambiguity number under the condition that no jump occurs in The operator is rounded down, and according to the test parameters, we can get

[0053] Step 2: The decision threshold for when some measured values ​​in the phase difference sequence measured multiple times have a ±π jump is determined as Th1=π, such as Figure 3 As shown in the figure, statistically, there are three possibilities for the difference between the maximum and minimum values ​​in the phase difference sequence of multiple measurements: (1) If the phase difference measurement value sequence does not jump at all or all jumps, the measured values ​​are all in [φ-4σ φ ,φ+4σ φ ] interval, so the maximum difference is 8σ φ ; (2) If some of the measured values ​​jump from near -π to near π, in extreme cases, the bottom of the tic-tac-toe shadow part close to -π is φ-4σ φ Jump to near π and become φ-4σ φ +2π, then the minimum difference is 2π-8σ φ (3) If some of the measured values ​​jump from near π to near -π, in extreme cases, the top of the cross-hatched part close to π is φ+4σ φ Jump to near -πφ+4σ φ -2π, then the minimum difference is 2π-8σ φ ; So the difference between the maximum and minimum values ​​in the phase difference sequence is selected as the decision value, in σ φ Under the premise of <π / 8, π is selected as the decision threshold to achieve the best distinction effect;

[0054] Step 3: According to the phase difference measurement accuracy σ φ and the number of measurements N, the decision threshold for all measured values ​​in the phase difference sequence of multiple measurements to jump is determined as (converted to radians, it is approximately 0.083π);

[0055] Step 4: According to the decision thresholds Th1 and Th2, the phase difference jump correction and the maximum integer K of the absolute value of the fuzzy number are adjusted according to different situations. According to the circular array formation parameters and the received signal frequency, the actual value of the phase difference between array element 1 and array element 2 is Remove the integer multiple of 2π and transform it to the phase main value interval. The phase difference measurement value should be 0.93π, but due to the influence of noise and the phase difference measurement accuracy σ φ is 15° (about 0.083π in radians), and the measured values ​​in the phase difference sequence have a probability of 99.9937% to be in the interval [φ-4σ φ ,φ+4σ φ ] that is, within [0.6π, 1.26π], then there are four possible phase difference sequences obtained from 16 measurements, such as Figure 4 to Figure 7 As shown, in order to fully take into account these four possibilities, the phase difference jump correction and the adjustment of the maximum integer K of the absolute value of the fuzzy number are performed according to different situations, which can be divided into the following sub-steps:

[0056] 1) Search for the maximum and minimum values ​​of the phase difference sequence measured multiple times and calculate their difference;

[0057] 2) If the difference is greater than Th1, the corresponding Figure 6 and Figure 7 In this case, proceed as follows:

[0058] a) Add 2π to all phase differences less than 0 in the sequence, and then calculate the average value of the sequence in Figure 6 The phase difference measurement sequence is obtained Figure 7 The phase difference measurement sequence is obtained

[0059] b) Transformed to So that it is within the phase main value interval (-π, π], Figure 6 In the case of out =0.947π, Figure 7 In the case of out = -0.989π;

[0060] c) Increase the maximum integer of the absolute value of the fuzzy number by 1, that is, K = K + 1 = 3. When traversing possible fuzzy numbers, Figure 6 The situation φ out The fuzzy number between the true value of the phase difference φ = 2π × 2.465 is 2, and Figure 7 The situation φ out The ambiguity number between the true value of the phase difference is 3, so if K is not adjusted, the deambiguation may fail;

[0061] 3) If the difference is less than or equal to Th1, the corresponding Figure 4 and Figure 5 In this case, proceed as follows:

[0062] a) Find the average value of the sequence Figure 4 In the case of out =0.904π, Figure 5 In the case of out = -0.929π;

[0063] b) Figure 5 φ out Located in the interval [-π, -π+Th2], i.e., [-π, -0.917π], the maximum integer of the absolute value of the fuzzy number is increased by 1, i.e., K=K+1=3, taking into account φ out The ambiguity number between the phase difference and the true value is 3;

[0064] Step 5: Perform the operation of step 4 on the multiple measured phase difference sequences of all baselines used for interferometer deambiguation and direction finding to obtain the average phase difference φ after all baselines have completed the jump correction out and the adjusted K respectively, take the maximum value of these K as the maximum integer of the absolute value of the phase difference ambiguity number, and take the average phase difference φ of all baselines ou The maximum K value is sent to the interferometer deambiguation direction finding process, thus completing the robust phase difference jump correction method.

Claims

1. A robust uniform circular array interferometer phase difference jump correction method, characterized in that: The following steps are involved: S1: According to the circular array parameters and the received signal frequency, calculate the maximum integer K of the absolute value of the phase difference ambiguity number under the condition that no jump occurs; S2: Determine the decision threshold for a portion of the measured values ​​in the phase difference sequence measured multiple times to have a ±π jump as Th1 = π; S3: According to the phase difference measurement accuracy σ φ and the number of measurements N, the decision threshold for all measured values ​​in the phase difference sequence of multiple measurements to jump is determined as S4: According to the decision thresholds Th1 and Th2, the phase difference jump correction and the maximum integer K of the absolute value of the fuzzy number are adjusted according to different situations; S5: Perform the operation of step S4 on the multiple measured phase difference sequences of all baselines used for interferometer deambiguation and direction finding, and obtain the average phase difference φ of all baselines after the jump correction is completed. out and the adjusted K respectively, take the maximum value of these K as the maximum integer of the absolute value of the phase difference ambiguity number, and take the average phase difference φ of all baselines out The maximum K value is sent to the interferometer deambiguation direction finding process to complete the phase difference jump correction.

2. A robust uniform circular array interferometer phase difference jump correction method according to claim 1, characterized in that: In step S2, the decision threshold is determined based on: Assume that the true value of the phase difference is φ and the phase difference measurement accuracy is σ φ , and the error follows a normal distribution, then the phase difference measurement value is in the range [φ-4σ φ ,φ+4σ φ ] has a probability of being within the interval of 99.9937%. Statistically, the difference between the maximum and minimum values ​​in the phase difference sequence measured multiple times has the following three possibilities: 1) If the phase difference measurement value sequence does not jump at all or all jumps, the maximum difference is 8σ φ ; 2) If some of the measured values ​​jump from near -π to near π, in extreme cases φ-4σ φ Jump to φ-4σ φ +2π, then the minimum difference is 2π-8σ φ ; 3) If some of the measured values ​​jump from near π to near -π, in extreme cases φ+4σ φ Jump to φ+4σ φ -2π, then the minimum difference is 2π-8σ φ ; In order to distinguish the first possibility from the latter two possibilities, the difference between the maximum and minimum values ​​in the phase difference sequence is selected as the decision metric. φ <π / 8, choose 8σ φ and 2π-8σ φ The average value π of is used as the decision threshold to achieve the best distinction effect.

3. The robust uniform circular array interferometer phase difference jump correction method according to claim 2, characterized in that: In step S3, the principle of 4 times is the same as step S2, divided by This is because the accuracy of N-time averaging is improved. If the average value of multiple measurements is If the measured values ​​are in the interval [-π, -π+Th2] or [π-Th2, π], it is considered that all measured values ​​have jumped.

4. The robust uniform circular array interferometer phase difference jump correction method according to claim 3, characterized in that: Step S4 is specifically as follows: 1) Search for the maximum and minimum values ​​of the phase difference sequence measured multiple times and calculate their difference; 2) If the difference is greater than Th1, perform the following processing: a) Add 2π to all phase differences less than 0 in the sequence, and then calculate the average value of the sequence b) Transformed to Make it within the phase principal value interval (-π,π], where mod(·) is the remainder with respect to 2π; c) Increase the maximum integer of the absolute value of the fuzzy number by 1, that is, K = K + 1; 3) If the difference is less than or equal to Th1, perform the following processing: a) Find the average value of the sequence b) If φ out If it is in the interval [-π, -π+Th2] or [π-Th2, π], increase the maximum integer of the absolute value of the fuzzy number by 1, that is, K=K+1, otherwise the value of K remains unchanged.

5. A robust uniform circular array interferometer phase difference jump correction system, characterized in that: A robust uniform circular array interferometer phase difference jump correction method as described in any one of claims 1 to 4 is used to correct the phase difference jump of the uniform circular array interferometer.

6. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is run, it executes a robust uniform circular array interferometer phase difference jump correction method as described in any one of claims 1 to 4.

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