An integer cycle acquisition method and device for pulse radar carrier phase ranging

Abstract

The present application belongs to the technical field of radar ranging, and particularly relates to an integer cycle acquisition method and device for pulse radar carrier phase ranging. The specific process of the method is as follows: step one, after target acquisition, a distance tracking loop is started to realize target echo envelope center tracking, and when the distance tracking loop meets the locking condition, an integer cycle acquisition loop is started; step two, the integer cycle acquisition loop is used to acquire an integer cycle for carrier phase ranging, and in the process of acquiring the integer cycle, a stable domain constraint, online stability judgment and bandwidth rollback mechanism are used to avoid dynamic instability caused by too narrow bandwidth, so that a smooth coarse distance and reliable integer cycle meeting the integer cycle judgment standard deviation constraint are obtained. The method and device can be used for reliable integer cycle acquisition in pulse radar carrier phase ranging.

Description

Technical Field

[0001] This invention belongs to the field of radar ranging technology, and specifically relates to a method and apparatus for obtaining integer cycles of pulse radar carrier phase ranging. Background Technology

[0002] In a pulse radar carrier phase ranging system, the target distance can be expressed as a combination of the integer-cycle distance and the fractional-cycle distance. For a single-station two-way radar, we have:

[0003] (1) in, For carrier wavelength, For carrier distance integer cycles, For the carrier fractional-cycle phase, The target distance. The distance interval between adjacent integer weeks is... Therefore, provided that the fractional-cycle phase can be obtained by an external phase measurement module, the integer-cycle phase... Whether it is reliable directly determines whether the final carrier phase ranging will occur. Integer multiple jump.

[0004] Traditional pulse radar typically obtains the coarse range of a target by measuring the time delay between the transmitted pulse and the received echo. : (2) in, The speed of electromagnetic wave propagation. The time delay is the two-way propagation delay of the echo. Pulse delay ranging has advantages such as no ambiguity, long operating range, and mature engineering implementation, thus it can provide a coarse range reference for carrier integer cycle acquisition. However, the accuracy of pulse coarse range is limited by factors such as signal bandwidth, sampling clock, pulse envelope center estimation accuracy, echo signal-to-noise ratio, and range gate position error, and may not be able to directly meet the integer cycle decision error constraint requirements required for carrier integer cycle decision.

[0005] Existing pulse radars often employ range tracking loops to track the center of the target echo envelope. A typical range tracking loop includes a front gate, a rear gate, a range error discriminator, a loop filter, and a range gate generator. The basic idea is to place two range gates, one before and one after, near the target acquisition range to accumulate echo energy. The energy difference between the front and rear gates is then used to construct a range error signal. The loop filter adjusts the position of the range gates so that their centers follow the target echo envelope center.

[0006] Ordinary range tracking loops are primarily designed for stable target tracking, and their loop bandwidth is typically chosen as a trade-off between dynamic response and noise suppression. A wider loop bandwidth is beneficial for target acquisition and fast dynamic tracking, but results in larger coarse range jitter in the output; a narrower loop bandwidth helps reduce thermal noise tracking errors, but reduces dynamic response capability and may even introduce dynamic hysteresis. If the output of an ordinary range tracking loop is directly used for carrier integer cycle decision, when the coarse range error approaches or exceeds... At this time, it is easy to make mistakes in judging integer cycles.

[0007] The existing technology has the following main shortcomings: First, the accuracy of coarse pulse range determination may not meet the carrier integer cycle decision requirement. Although pulse delay ranging can provide unambiguous coarse range, its error is affected by signal bandwidth, sampling rate, envelope center estimation, and signal-to-noise ratio. When the coarse range error approaches or exceeds... At that time, directly using it to determine the integer cycle of the carrier can lead to cycle skipping risk.

[0008] Second, conventional range tracking loops are not specifically designed for integer cycle acquisition. The primary goal of traditional range tracking loops is to stably track the target echo center, rather than to ensure that the output coarse range meets the carrier half-wavelength criterion. Their loop parameters typically struggle to simultaneously achieve acquisition, dynamic tracking, and integer cycle decision accuracy.

[0009] Third, fixed-bandwidth loops struggle to balance noise suppression and dynamic response. Wideband loops exhibit significant output jitter, hindering integer cycle decision-making; while narrowband loops can reduce noise, they may introduce hysteresis or loss of lock when the target changes dynamically. Therefore, relying solely on fixed-bandwidth distance tracking loops is insufficient to reliably obtain integer cycles.

[0010] Fourth, the reliability of single-cycle integer-cycle hard decision is insufficient. If the integer cycle is obtained directly by rounding the single coarse distance and fractional-cycle distance, the statistical characteristics of coarse distance error, distance loop stability, thermal noise tracking error, and multi-cycle consistency are not fully considered, and the cycle jump is easily caused by instantaneous abnormal echoes or random noise. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides a method and apparatus for obtaining integer cycles in pulse radar carrier phase ranging. After the range tracking loop is locked, the coarse range output is processed a second time based on the integer cycle decision standard deviation constraint: on the one hand, thermal noise tracking error is suppressed by reducing the equivalent loop noise bandwidth; on the other hand, dynamic instability caused by excessively narrow bandwidth is avoided through stability domain constraints, online stability decision, and bandwidth back-off mechanism; finally, the method outputs a smooth coarse range and reliable integer cycles that meet the integer cycle decision error constraint requirements.

[0012] The technical solution for implementing the present invention is as follows: In a first aspect, the present invention provides a method for obtaining integer cycles of pulse radar carrier phase ranging, the specific process of which is as follows: Step 1: After target acquisition, start the range tracking loop to track the center of the target echo envelope. Once the range tracking loop meets the locking conditions, start the integer cycle acquisition loop. Step 2: Obtain the integer cycles used for carrier phase ranging using the integer cycle acquisition loop. The specific process is as follows: First, calculate the maximum allowable equivalent loop noise bandwidth under the integer cycle decision thermal noise constraint, and set the target bandwidth based on the maximum allowable equivalent loop noise bandwidth and the bandwidth margin coefficient; Secondly, the stability region of the loop parameters of the distance tracking loop is constructed, and the correspondence between the loop parameters and the equivalent loop noise bandwidth is established to form a parameter library. ; Next, based on the target bandwidth, a slowly decreasing bandwidth command is set, and loop parameters that satisfy the bandwidth command and have the smallest jump are selected from the parameter library. Under the currently selected loop parameters, if the loop is stable and the sliding standard deviation has not yet met the integer cycle decision standard deviation constraint, the bandwidth continues to decrease; if the loop is unstable, bandwidth backoff is performed; when the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer cycle decision standard deviation constraint, the smooth coarse distance is calculated; candidate integer cycles are calculated using the smooth coarse distance and the externally input fractional cycle distance. Finally, a consensus decision is made on the candidate integer weeks within multiple consecutive update cycles. When the consensus decision is satisfied, the integer weeks and smoothed coarse distance are output for pulse radar carrier phase ranging.

[0013] Optionally, the present invention constructs a loop parameter stability region and establishes a parameter library by defining the correspondence between loop parameters and bandwidth. The specific process is as follows: Distance tracking loop adopts Ring road or Ring road; Constructing the stability region of loop parameters Construct multiple sets of loop parameters within the stability region. When adopting When on the loop, =0; Obtain each set of loop parameters Corresponding equivalent loop noise bandwidth Establish loop parameters With equivalent loop noise bandwidth The correspondence forms a parameter library for:

[0014] in, This represents the mapping function from loop parameters to the equivalent loop noise bandwidth.

[0015] Optionally, the present invention sets a slowly decreasing bandwidth instruction based on the target bandwidth as follows:

[0016] in, For target bandwidth, This is the current bandwidth instruction. This is the bandwidth instruction for the next stage. The bandwidth reduction factor is denoted by , and max() takes the larger of the two terms in parentheses.

[0017] Optionally, the present invention selects loop parameters from a parameter library that satisfy the bandwidth command and have the smallest jump, wherein the selection criteria are: Let the current loop parameters be: Select a set of candidate parameters that meet the bandwidth command from the parameter library. :

[0018] in, For bandwidth matching tolerance; From the candidate parameter set Select the set of loop parameters that has the smallest jump with the current loop parameters. :

[0019] in, To select from the candidate parameter set Choose the loop parameters that minimize the objective function. , Bandwidth matching weights, For parameter jump constraint weights, For the parameter normalization matrix, It is the square of the second norm of the vector.

[0020] Optionally, the determination of whether the loop is stable in this invention specifically involves: calculating the average absolute residual of the predicted distance within the detection window. residual standard deviation and residual growth rate If satisfied The loop is considered stable if it is stable otherwise, and unstable if it is not. For the mean absolute residual threshold, The standard deviation threshold of the residuals. This is represented as the threshold for the residual growth rate.

[0021] Optionally, if the loop is unstable under the currently selected loop parameters, the present invention performs bandwidth rollback to... :

[0022] in, This is the bandwidth increase factor. The safe bandwidth during the most recent stable operation, min() is to take the smaller of the two values ​​in parentheses; Subsequently according to Select new loop parameters from the parameter library to restore dynamic tracking capability.

[0023] Optionally, the present invention includes an integer-week decision standard deviation constraint: ,in, For the sliding standard deviation, This refers to the range interval corresponding to adjacent integer cycles of a single-station two-way radar. The carrier wavelength; When the bandwidth reaches near the target bandwidth and the sliding standard deviation is satisfied Calculate the smoothed coarse distance. ;

[0024] in, To smooth out the weights, For the first Target distance estimation for each loop cycle For the first Loop cycle speed estimation, For the loop update cycle, For the length of the sliding statistics window, .

[0025] Optionally, if the loop is stable but the sliding standard deviation does not meet the requirements of the present invention... Then the following processing will be performed: 1) If the current bandwidth is still greater than If so, then continue to reduce bandwidth; 2) If the current bandwidth has reached However, the sliding standard deviation was still not satisfied. Then extend the statistical window length. Or increase the number of accumulated pulses ; 3) If the statistical window length is extended Or increase the number of accumulated pulses Still unable to satisfy If the current signal-to-noise ratio or target dynamic conditions are insufficient to reliably obtain integer cycles, the distance tracking state is maintained and integer cycles are not output for the time being. 4) If the distance tracking loop is unstable, increase the bandwidth, restore dynamic tracking, and wait for it to stabilize again before reducing the bandwidth.

[0026] Optionally, the present invention utilizes a smooth coarse distance The fractional distance from the external input Calculate candidate integer weeks :

[0027] in, Indicates rounding down; Indicates decimal distance; The consistency determination for candidate integer weeks within multiple consecutive update cycles is specifically as follows: In length of Within the integer week confirmation window, for candidate integer weeks Perform statistics, if a certain integer The number of times it appears within the integer week confirmation window is no less than the consistency confirmation threshold. Then output the integer week. Smooth coarse distance and valid mark :

[0028] Otherwise, do not output the integer week. and smooth coarse distance Only output valid flags. : .

[0029] In a second aspect, the present invention provides an integer cycle acquisition device for pulse radar carrier phase ranging, comprising: a range tracking loop and an integer cycle acquisition loop; wherein... The range tracking loop is used to track the center of the target echo envelope after target acquisition, and to start the integer cycle acquisition loop after the locking condition is met; An integer-cycle acquisition loop is used to calculate the maximum permissible equivalent loop noise bandwidth under the integer-cycle decision thermal noise constraint, and to set the target bandwidth based on the maximum permissible equivalent loop noise bandwidth and bandwidth margin coefficient. A stability domain for the loop parameters of the range tracking loop is constructed, and a parameter library is established to correspond to the loop parameters and the equivalent loop noise bandwidth. Based on the target bandwidth, a slowly decreasing bandwidth command is set, and the loop parameter with the smallest jump that satisfies the bandwidth command is selected from the parameter library. Under the currently selected loop parameter, if the loop is stable and the sliding standard deviation has not yet met the integer-cycle decision standard deviation constraint, the bandwidth continues to decrease; if the loop is unstable, bandwidth backoff is performed. When the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer-cycle decision standard deviation constraint, a smoothed coarse distance is calculated. Candidate integer cycles are calculated using the smoothed coarse distance and the externally input fractional-cycle distance. Consistency decisions are made for candidate integer cycles within multiple consecutive update cycles. When the consistency decision is satisfied, the integer cycle and smoothed coarse distance are output for pulse radar carrier phase ranging.

[0030] Beneficial effects: This invention can provide reliable integer cycles for pulse radar carrier phase ranging without limiting the final ranging fusion method; by dividing the work between the range tracking loop and the integer cycle acquisition loop, coarse range jitter can be further reduced on the basis of stable target tracking; by calculating the target bandwidth, selecting the stability domain parameters, online stability backoff, and confirming the sliding standard deviation, the smoothed coarse range can meet the integer cycle decision conditions; by using multi-cycle consistency decision, the reliability and continuity of integer cycle output can be improved. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 Obtain the loop flowchart for integer cycles. Detailed Implementation

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0035] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0036] The design concept of this invention is as follows: A range tracking loop is used to stably track the echo envelope center after target acquisition, outputting an initial coarse range sequence. An integer cycle acquisition loop is activated after the range tracking loop locks on. Its function is neither target acquisition nor outputting the final precise range, but rather to smooth and confirm the reliability of the range tracking loop output based on carrier-oriented integer cycle decisions, outputting a smoothed coarse range. and carrier integer cycles It is used for pulse radar carrier phase ranging.

[0037] like Figure 1 As shown, this invention provides a method for obtaining integer cycles of carrier phase ranging in pulse radar. The specific process is as follows: Step 1: After target acquisition, start the range tracking loop to track the center of the target echo envelope. Once the range tracking loop meets the locking conditions, start the integer cycle acquisition loop. Step 2: Obtain the integer cycles used for carrier phase ranging using the integer cycle acquisition loop. The specific process is as follows: First, calculate the maximum allowable equivalent loop noise bandwidth under the integer cycle decision thermal noise constraint, and set the target bandwidth based on the maximum allowable equivalent loop noise bandwidth and the bandwidth margin coefficient; Secondly, the stability region of the loop parameters of the distance tracking loop is constructed, and the correspondence between the loop parameters and the equivalent loop noise bandwidth is established to form a parameter library. ; Next, based on the target bandwidth, a slowly decreasing bandwidth command is set, and loop parameters that satisfy the bandwidth command and have the smallest jump are selected from the parameter library. Under the currently selected loop parameters, if the loop is stable and the sliding standard deviation has not yet met the integer cycle decision standard deviation constraint, the bandwidth continues to decrease; if the loop is unstable, bandwidth backoff is performed; when the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer cycle decision standard deviation constraint, the smooth coarse distance is calculated; candidate integer cycles are calculated using the smooth coarse distance and the externally input fractional cycle distance. Finally, a consensus decision is made on the candidate integer weeks within multiple consecutive update cycles. When the consensus decision is satisfied, the integer weeks and smoothed coarse distance are output for pulse radar carrier phase ranging.

[0038] The output in this embodiment includes: (3) in, To satisfy the smooth coarse distance of the integer week decision standard deviation constraint, For integer weeks, A valid indicator. When When, it indicates that the current integer week meets the requirements for stability, standard deviation, and multi-period consistency; when When the condition is met, it indicates that reliable integer cycles will not be output for the time being under the current conditions.

[0039] The above process will be explained in detail below: Signal model and carrier phase ranging model: Radar transmits pulse signals It can be represented as: (4) in, For the amplitude of the transmitted signal, For pulse envelope, For carrier frequency, This is the initial phase.

[0040] Let the first The target distance within each loop update cycle is The two-way propagation delay of the echo for: (5) in, It is the speed of light.

[0041] Receive echo It can be represented as: (6) in, Echo amplitude, Additional phase introduced for target scattering and channeling. It is noise.

[0042] After orthogonal downconversion and matched filtering, the echo can be used to obtain a complex baseband signal. : (7) in, For carrier wavelength, For complex noise, For the first The equivalent amplitude coefficient of the echo after orthogonal downconversion and matched filtering within each loop update cycle is related to the target scattering intensity, propagation loss, and receiver channel gain.

[0043] Distance tracking loop The range tracking loop consists of a range gate generator, a range error discriminator, and a range loop filter. Its function is to generate a stable coarse range tracking output after target acquisition, providing input for the integer cycle acquisition loop.

[0044] Step 1: Generate front and rear gate settings The range gate generator produces the target echo center sampling position based on the target range estimate from the previous cycle. A front gate and a rear gate are set before and after it. Within each loop update cycle, the sampling sets for the front and back gates are as follows: (8) (9) in, Indicates the front gate, Indicates a back gate. and These represent the left and right boundaries of the front-wave gate, respectively. and These represent the left and right boundaries of the back gate, respectively.

[0045] As a specific implementation method, the front and rear gates can be set symmetrically according to the target echo center: (10) (11) in, This refers to the gate width. A larger gate width can be used in the initial stage of loop capture. It can be reduced after locking. To suppress external noise in the echo.

[0046] Step 2: Incoherent power accumulation between front and rear gates From complex baseband signal Discrete complex baseband samples obtained by sampling The sampling period is ; Complex baseband samples within the preceding and following gates Perform incoherent power accumulation: (12) (13) in, and Indicates complex baseband samples within the front-gate and back-gate. Results of incoherent power accumulation.

[0047] When the front and rear gates are symmetrical about the center of the true echo envelope, and They are approximately equal; however, they differ when the gate center deviates from the true echo envelope center.

[0048] Step 3: Distance Error Identification Define the normalized distance error discrimination value for: (14) in, To prevent the denominator from being too small a positive number, the distance error can be approximated as follows when the distance error discriminator is within its linear range: : (15) in, This represents the distance error discriminator gain, in meters. It can be obtained through theoretical approximation, ground calibration, simulation calibration, or online calibration.

[0049] Step 4: Distance Loop Filtering Range loop filters can be used or Loop filter. Taking a filter as an example, its prediction equation is: (16) (17) (18) in, For the loop update cycle, , , The first Predicting distance, velocity, and acceleration for each loop cycle. , , The first Predicted distance, predicted velocity, and predicted acceleration after loop periodic filtering.

[0050] Update using the output of the distance error discriminator: (19) (20) (twenty one) in, These are the range tracking loop filter parameters, i.e., the loop parameters. If using... Filter, then let It only updates the distance and speed status.

[0051] Step 5: Distance tracking loop lock decision The integer cycle acquisition loop is only initiated after the distance tracking loop is locked. Let the lock decision window length be... If the following conditions are met: (twenty two) And the standard deviation of the distance error satisfies: (twenty three) If the distance tracking loop is locked, it is considered locked; otherwise, normal distance tracking is maintained, and the integer cycle acquisition loop is not initiated. For the first The distance error estimate for each loop update cycle; This represents the mean absolute error threshold in the distance tracking loop locking decision; This is the standard deviation threshold for distance error; This represents the mean of the distance error estimates within the locked decision window.

[0052] Integer cycles obtain loops The working principle of the integer cycle acquisition loop of this invention is as follows: If the external fractional-cycle phase precision measurement module outputs fractional-cycle phase The corresponding fractional-week distance can be expressed as: (twenty four) in, This represents the range interval corresponding to adjacent integer cycles of a single-station, two-way radar.

[0053] This invention utilizes smooth coarse distance The fractional distance from the external input Get the integer week: (25) Equation (25) is only used for obtaining integer weeks. This invention is not limited to this. The measurement method is not limited to how the external module combines integer and fractional cycles into the final absolute distance.

[0054] The specific process for obtaining the cycle of integer cycles is as follows: The inputs to the integer-cycle acquisition loop are: the locked distance tracking output, the current signal-to-noise ratio, the loop update period, the accumulated pulse count, the distance error discriminator gain, the carrier wavelength, and the fractional-cycle distance from the external input; the outputs are: smoothed coarse distance, integer cycles, and a valid flag. The flowchart is attached. Figure 1 As shown.

[0055] Step 1: Calculate the target bandwidth based on the distance tracking error constraint caused by thermal noise. The distance tracking error caused by thermal noise in the distance tracking loop can be expressed as: (26) in, These are constants related to the characteristics of the pulse width or distance error discriminator. For the distance error discriminator gain, For the loop update cycle, This is the current equivalent loop noise bandwidth. For input signal-to-noise ratio, This represents the number of pulses accumulated within a single loop update cycle.

[0056] To enable coarse distances to be used for carrier integer cycle decisions, integer cycle decision error constraints must be met. When using the three-standard-deviation criterion, we have: (27) Substituting equation (26) into equation (27), we obtain the maximum permissible equivalent loop noise bandwidth that satisfies the integer cycle decision thermal noise constraint. : (28) To allow for project margin, the target bandwidth is set for the loop through integer cycles. for: (29) in, This represents the bandwidth margin coefficient. In practical systems, the target's dynamic error also needs to be considered; therefore, it's not a simple one-step switch. Instead, it gradually approaches.

[0057] Step 2: Confirm Parameter stability region Adjusting loop parameters At this time, the loop stability condition must be met first.

[0058] If adopted The stability condition of a loop is: (30) If adopted The stability condition of a loop is: (31) Define the stability region of the loop parameters: (32) All parameter adjustments for the loop obtained in integer cycles are in Completed within the specified time.

[0059] Step 3: Establish the correspondence between loop parameters and bandwidth for Distance tracking loop, dimensionless bandwidth metric can be defined. : (33) When a consistent one-sided equivalent noise bandwidth is defined, it can be written as: (34) in, This represents the mapping function from loop parameters to the equivalent loop noise bandwidth.

[0060] If different normalization definitions are used in actual systems, the fixed proportional coefficients introduced by the one-sided / two-sided equivalent noise bandwidth definition, discretization period and filter implementation method can be incorporated into the parameter table without affecting the idea of ​​parameter control based on equivalent noise bandwidth in this invention.

[0061] In practice, a parameter library can be formed offline by generating the correspondence between loop parameters that meet stability conditions and the equivalent loop noise bandwidth. : (35) This parameter library only retains parameter combinations that satisfy stability conditions, and is categorized as follows: Sort by size from largest to smallest or smallest to largest, for online lookup of loops for integer cycles.

[0062] Step 4: Slowly decrease bandwidth command Let the current bandwidth command be The target bandwidth is To avoid transient errors or tracking instability caused by sudden changes in loop bandwidth, the loop acquisition for integer cycles uses slowly decreasing bandwidth commands: (36) in, This is the bandwidth instruction for the next stage. As a bandwidth reduction factor, it can usually be taken as... ,max() is to take the larger of the two terms in the parentheses. If the current bandwidth has reached the vicinity of the target bandwidth, that is, if the equation (37) is satisfied, then stop reducing the bandwidth and enter the sliding standard deviation confirmation stage; otherwise, perform loop parameter selection based on minimum parameter jump and online stability and dynamic tracking capability judgment until the condition of equation (37) is satisfied.

[0063] (37) in, The target bandwidth proximity tolerance is used to determine whether the current actual equivalent loop noise bandwidth has reached the vicinity of the target bandwidth.

[0064] Parameter selection based on minimum parameter jump: To achieve a stable transition, the current loop parameters are defined as follows: (38) In the parameter library Select a set of candidate parameters that meet the target bandwidth for the next stage: (39) in, To allow for bandwidth matching tolerance.

[0065] Select the set of loop parameters from the candidate parameter set that has the smallest jump with the current loop parameter. : (40) in, To represent from the candidate parameter set Choose the loop parameters that minimize the objective function (i.e., the right side of equation 40 is the objective function). , Bandwidth matching weights, For parameter jump constraint weights, For the parameter normalization matrix, The value is the square of the vector's L2 norm. This method guarantees: first, the loop parameters always remain within the stable region; second, the bandwidth decreases gradually along the target direction; and third, the loop parameters change only slightly between adjacent stages, avoiding transient shocks caused by direct and significant changes in the loop parameters.

[0066] Online stability and dynamic tracking capability assessment: After each loop parameter update, the loop is first run under the current parameters for integer cycles. Each loop cycle is evaluated, and online stability and dynamic tracking capabilities are assessed.

[0067] Define the predicted distance residual: (41) Calculate the mean absolute residual within the detection window: (42) And the residual growth rate: (43) in, This represents the standard deviation of the residuals within the current detection window.

[0068] If equation (44) is satisfied, the loop is considered stable under the current bandwidth and the target can be tracked dynamically. If the sliding standard deviation does not meet the integer cycle decision standard deviation constraint, the bandwidth can be further reduced. (44) in, For the mean absolute residual threshold, The standard deviation threshold of the residuals. This is represented as the threshold for the residual growth rate.

[0069] If equation (44) is not satisfied, it is considered that the current bandwidth is too low or the target is dynamically enhanced, and bandwidth rollback is performed: (45) in, This is the bandwidth increase factor. The safe bandwidth during the most recent stable operation is given, and min() takes the smaller of the two values ​​within the parentheses. Then, based on... Select a new one from the parameter library. To restore dynamic tracking capabilities.

[0070] Step 5: Confirm the sliding standard deviation Once the actual bandwidth gradually decreases to near the target bandwidth, the integer cycle acquisition loop enters the sliding standard deviation confirmation phase. Let the sliding statistical window length be... After detrending the distance output, the standard deviation is calculated: (46) in, The distance trend obtained by linear or quadratic fitting within the window is used to subtract the distance changes caused by the actual motion of the target.

[0071] If the following conditions are met: (47) This indicates that the current distance tracking output has reached the accuracy requirement for integer cycle acquisition, and a smooth coarse distance is formed for integer cycle decision. As a specific implementation method, one approach is: (48) in, To smooth out the weights, uniform weights, exponential weights, or signal-to-noise ratio weights can be used. For the first Predicted speed for each loop cycle. For the loop update cycle, For the length of the sliding statistics window, This is used to shift historical distance estimates within a window to the current time, reducing the average lag caused by target motion. If the target motion is very slow, the current tracking output can also be used directly. Or the detrended mean within the window as .

[0072] If equation (47) is not satisfied, proceed as follows; if it is satisfied, proceed to step 6. 1) If the current bandwidth is still greater than Then continue to reduce the bandwidth according to formula (36); 2) If the current bandwidth has reached However, if the sliding standard deviation still does not satisfy equation (47), then the statistical window should be extended. Or increase the number of accumulated pulses ; 3) If the statistical window length is extended Or increase the number of accumulated pulses If equation (47) is still not satisfied, it is considered that the current signal-to-noise ratio or target dynamic conditions are insufficient to reliably obtain integer cycles, the distance tracking state is maintained, and integer cycles are not output for the time being; 4) If the tracking loop is unstable, increase the bandwidth according to formula (45) to restore the dynamic tracking capability, and wait for the next time to stabilize before reducing the bandwidth again.

[0073] Step 6: Integer week calculation and multi-period consistency confirmation When smoothing coarse distance After meeting the half-wavelength standard deviation criterion, the external fractional distance is used. Calculate candidate integer weeks : (49) To reduce the risk of cycle skipping caused by transient anomalies, In length of Within the integer week confirmation window, for candidate integer weeks Perform statistics, if a certain integer The number of times it appears within the integer week confirmation window is no less than the consistency confirmation threshold. ,Right now (50) in, This is an indicator function that takes the value 1 when the condition inside the parentheses is true, and 0 otherwise.

[0074] Then output the integer week. Smooth coarse distance and valid mark : (51) Otherwise, do not output the integer week. and smooth coarse distance Only output valid flags. : (52) in, For consistency confirmation thresholds, it is generally acceptable to take it as 1. The majority proportion. Therefore, integer cycle outputs not only depend on the single rounding result, but also need to satisfy the moving standard deviation and multi-cycle consistency conditions.

[0075] Compared with the prior art, the present invention has the following technical advantages: (1) Compared with the ordinary pulse coarse ranging method, the present invention does not directly use the single pulse coarse distance for integer cycle decision, but obtains the smooth coarse distance that satisfies the standard deviation constraint of integer cycle decision through distance tracking, bandwidth reduction, smooth confirmation and consistency judgment, thus reducing the risk of integer cycle misjudgment.

[0076] (2) Compared with the ordinary range tracking loop, the present invention adds an integer cycle acquisition loop after the range tracking loop is locked. The ordinary range tracking loop is mainly used for stable target tracking, while the integer cycle acquisition loop of the present invention is specifically designed for the accuracy requirements of carrier integer cycle decision.

[0077] (3) Compared with the fixed bandwidth loop, the present invention solves the target bandwidth based on the standard deviation constraint of the integer cycle decision and gradually reduces the bandwidth in the stable domain; at the same time, it retains the online stability decision and bandwidth back-off mechanism, thus it can take into account both noise suppression and dynamic response.

[0078] (4) Compared with single-cycle hard decision, the present invention first confirms the sliding standard deviation and then makes a multi-cycle integer cycle consistency decision, which can reduce the risk of cycle skipping caused by instantaneous noise, abnormal echo and fractional cycle phase abnormality.

[0079] (5) Compared with the method of directly changing the loop parameters, the present invention selects the loop parameters by means of stability domain constraints and minimum parameter jump, so that the bandwidth reduction process is more stable and the transient error caused by parameter change is reduced.

[0080] This application provides an integer cycle acquisition device for pulse radar carrier phase ranging, comprising: a range tracking loop and an integer cycle acquisition loop; wherein... The range tracking loop is used to track the center of the target echo envelope after target acquisition, and to start the integer cycle acquisition loop after the locking condition is met; An integer-cycle acquisition loop is used to calculate the maximum permissible equivalent loop noise bandwidth under the integer-cycle decision thermal noise constraint, and to set the target bandwidth based on the maximum permissible equivalent loop noise bandwidth and bandwidth margin coefficient. A stability domain for the loop parameters of the range tracking loop is constructed, and a parameter library is established to correspond to the loop parameters and the equivalent loop noise bandwidth. Based on the target bandwidth, a slowly decreasing bandwidth command is set, and the loop parameter with the smallest jump that satisfies the bandwidth command is selected from the parameter library. Under the currently selected loop parameter, if the loop is stable and the sliding standard deviation has not yet met the integer-cycle decision standard deviation constraint, the bandwidth continues to decrease; if the loop is unstable, bandwidth backoff is performed. When the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer-cycle decision standard deviation constraint, a smoothed coarse distance is calculated. Candidate integer cycles are calculated using the smoothed coarse distance and the externally input fractional-cycle distance. Consistency decisions are made for candidate integer cycles within multiple consecutive update cycles. When the consistency decision is satisfied, the integer cycle and smoothed coarse distance are output for pulse radar carrier phase ranging.

[0081] Example: The following describes the implementation of this invention using a typical low-frequency pulse radar precision ranging scenario.

[0082] Let the radar carrier frequency be: (53) The carrier wavelength is: (54) For a single-station two-way radar, the distance interval between adjacent integer cycles is: (55) Therefore, the basic goal of obtaining the loop in integer cycles is to make the smooth coarse distance error satisfy the half-wavelength criterion.

[0083] A set of typical simulation parameters are shown in Table 1 below.

[0084] Table 1 Simulation Parameters

[0085] In the simulation, the actual distance to the target is set as follows: (56) in, For target speed; Noisy pulse coarse range observations are as follows: (57) in, It is zero-mean Gaussian noise.

[0086] The simulation implementation steps are as follows.

[0087] 1. Generate target true distance and coarse distance observations with noisy impulses; 2. Utilize a range tracking loop for stable target tracking; 3. After the distance tracking loop is locked, the target bandwidth is calculated based on thermal noise constraints; 4. For integer cycles, the loop bandwidth is gradually reduced according to the bandwidth command, and the loop parameters are selected within the stability region. ; 5. Perform online stability assessment at each bandwidth level. If stable, continue to reduce bandwidth; if unstable, reduce bandwidth. 6. When the sliding standard deviation satisfies the integer cycle decision standard deviation constraint At that time, a smooth coarse distance is formed; 7. Calculate the candidate integer cycles using the external decimal cycle distance and formula (49); 8. Output integer cycles, smooth coarse distance, and valid flags through multi-cycle consistency decision.

[0088] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for obtaining integer cycles of carrier phase ranging in pulse radar, characterized in that, The specific process is as follows: Step 1: After target acquisition, start the range tracking loop to track the center of the target echo envelope. Once the range tracking loop meets the locking conditions, start the integer cycle acquisition loop. Step 2: Obtain the integer cycles used for carrier phase ranging using the integer cycle acquisition loop. The specific process is as follows: First, calculate the maximum allowable equivalent loop noise bandwidth under the integer cycle decision thermal noise constraint, and set the target bandwidth based on the maximum allowable equivalent loop noise bandwidth and the bandwidth margin coefficient; Secondly, the stability region of the loop parameters of the distance tracking loop is constructed, and the correspondence between the loop parameters and the equivalent loop noise bandwidth is established to form a parameter library. ; Next, based on the target bandwidth, a slowly decreasing bandwidth command is set, and the loop parameter that satisfies the bandwidth command and has the smallest jump is selected from the parameter library. Under the currently selected loop parameter, if the loop is stable and the sliding standard deviation has not yet met the integer cycle decision standard deviation constraint, the bandwidth is further reduced. If the loop is unstable, bandwidth backoff is performed; when the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer cycle decision standard deviation constraint, the smoothed coarse distance is calculated; candidate integer cycles are calculated using the smoothed coarse distance and the fractional cycle distance of the external input. Finally, a consensus decision is made on the candidate integer weeks within multiple consecutive update cycles. When the consensus decision is satisfied, the integer weeks and smoothed coarse distance are output for pulse radar carrier phase ranging.

2. The method for obtaining integer cycles of carrier phase ranging for pulse radar according to claim 1, characterized in that, Construct the stability region of the loop parameters and establish the correspondence between the loop parameters and the bandwidth to form a parameter library. The specific process is as follows: Distance tracking loop adopts Ring road or Ring road; Constructing the stability region of loop parameters Construct multiple sets of loop parameters within the stability region. When adopting When on the loop, =0; Obtain each set of loop parameters Corresponding equivalent loop noise bandwidth Establish loop parameters With equivalent loop noise bandwidth The correspondence forms a parameter library for: in, This represents the mapping function from loop parameters to the equivalent loop noise bandwidth.

3. The method for obtaining integer cycles of carrier phase ranging for pulse radar according to claim 2, characterized in that, Based on the target bandwidth, the bandwidth command is set to decrease slowly as follows: in, For target bandwidth, This is the current bandwidth instruction. This is the bandwidth instruction for the next stage. The bandwidth reduction factor is denoted by , and max() takes the larger of the two terms in the parentheses.

4. The method for obtaining integer cycles of carrier phase ranging for pulse radar according to claim 3, characterized in that, Select the loop parameter from the parameter library that satisfies the bandwidth command and has the smallest jump, where the selection criteria are: Let the current loop parameters be: Select a set of candidate parameters that meet the bandwidth command from the parameter library. : in, For bandwidth matching tolerance; From the candidate parameter set Select the set of loop parameters that has the smallest jump with the current loop parameters. : in, To select from the candidate parameter set Choose the loop parameters that minimize the objective function. , Bandwidth matching weights, For parameter jump constraint weights, For the parameter normalization matrix, It is the square of the second norm of the vector.

5. The method for obtaining integer cycles of pulse radar carrier phase ranging according to claim 4, characterized in that, The determination of loop stability is specifically as follows: calculate the mean absolute residual of the predicted distance within the detection window. residual standard deviation and residual growth rate If satisfied The loop is considered stable if it is stable otherwise, and unstable if it is not. For the mean absolute residual threshold, The standard deviation threshold of the residuals. This is represented as the threshold for the residual growth rate.

6. The method for obtaining integer cycles of carrier phase ranging for pulse radar according to claim 5, characterized in that, If the loop is unstable under the currently selected loop parameters, then bandwidth rollback will be performed. : in, This is the bandwidth increase factor. The safe bandwidth during the most recent stable operation, min() is to take the smaller of the two values ​​in parentheses; Subsequently according to Select new loop parameters from the parameter library to restore dynamic tracking capability.

7. The method for obtaining integer cycles of carrier phase ranging for pulse radar according to claim 6, characterized in that, The standard deviation constraint for integer week decisions is: ,in, For the sliding standard deviation, This refers to the range interval corresponding to adjacent integer cycles of a single-station two-way radar. The carrier wavelength; When the bandwidth reaches the target bandwidth Near and the sliding standard deviation satisfies Calculate the smoothed coarse distance. ; in, To smooth out the weights, For the first Target distance estimation for each loop cycle For the first Loop cycle speed estimation, For the loop update cycle, For the length of the sliding statistics window, .

8. The method for obtaining integer cycles of pulse radar carrier phase ranging according to claim 7, characterized in that, If the loop is stable, but the sliding standard deviation does not meet the requirements. Then the following processing will be performed: 1) If the current bandwidth is still greater than If so, then continue to reduce bandwidth; 2) If the current bandwidth has reached However, the sliding standard deviation was still not satisfied. Then extend the statistical window length. Or increase the number of accumulated pulses ; 3) If the statistical window length is extended Or increase the number of accumulated pulses Still unable to satisfy If the current signal-to-noise ratio or target dynamic conditions are insufficient to reliably obtain integer cycles, the distance tracking state is maintained and integer cycles are not output for the time being. 4) If the distance tracking loop is unstable, increase the bandwidth, restore dynamic tracking, and wait for it to stabilize again before reducing the bandwidth.

9. The method for obtaining integer cycles of pulse radar carrier phase ranging according to claim 8, characterized in that, Utilizing smooth coarse distance The fractional distance from the external input Calculate candidate integer weeks : in, Indicates rounding down; Indicates decimal distance; The consistency determination for candidate integer weeks within multiple consecutive update cycles is specifically as follows: In length of Within the integer week confirmation window, for candidate integer weeks Perform statistics, if a certain integer The number of times it appears within the integer week confirmation window is no less than the consistency confirmation threshold. Then output the integer week. Smooth coarse distance and valid mark : Otherwise, do not output the integer week. and smooth coarse distance Only output valid flags: 。 10. An integer cycle acquisition device for pulse radar carrier phase ranging, characterized in that, include: Distance tracking loop and integer cycle acquisition loop; where, The range tracking loop is used to track the center of the target echo envelope after target acquisition, and to start the integer cycle acquisition loop after the locking condition is met; An integer-cycle acquisition loop is used to calculate the maximum permissible equivalent loop noise bandwidth under the integer-cycle decision thermal noise constraint, and to set the target bandwidth based on the maximum permissible equivalent loop noise bandwidth and bandwidth margin coefficient. A stability domain for the loop parameters of the range tracking loop is constructed, and a parameter library is established to correspond to the loop parameters and the equivalent loop noise bandwidth. Based on the target bandwidth, a slowly decreasing bandwidth command is set, and the loop parameter with the smallest jump that satisfies the bandwidth command is selected from the parameter library. Under the currently selected loop parameter, if the loop is stable and the sliding standard deviation has not yet met the integer-cycle decision standard deviation constraint, the bandwidth continues to decrease; if the loop is unstable, bandwidth backoff is performed. When the bandwidth reaches near the target bandwidth and the sliding standard deviation meets the integer-cycle decision standard deviation constraint, a smoothed coarse distance is calculated. Candidate integer cycles are calculated using the smoothed coarse distance and the externally input fractional-cycle distance. Consistency decisions are made for candidate integer cycles within multiple consecutive update cycles. When the consistency decision is satisfied, the integer cycle and smoothed coarse distance are output for pulse radar carrier phase ranging.

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