A high-precision ranging method for pulse radar based on carrier integer cycle and fractional cycle
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2026-07-10
- Publication Date
- 2026-08-07
AI Technical Summary
[0006]第一，传统脉冲雷达测距精度受信号带宽限制
本发明提供一种基于载波整数周和小数周的脉冲雷达高精度测距方法，能够将脉冲雷达的无模糊粗测距能力和载波相位的高精度测距能力统一起来，其中，首先通过目标无模糊脉冲粗距离确定载波半波长整数周，通过载波小数周相位确定半波长区间内的载波小数周距离，然后将目标距离表示为载波半波长整数周表征的距离和载波小数周距离的组合，从而在不显著增加硬件复杂度的前提下提高脉冲雷达测距精度；此外，本发明通过组合一致性判断和质量控制，可降低相位异常、粗距离异常或整数周错误导致的距离跳变风险。
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Abstract
Description
Technical Field
[0001] This invention belongs to the fields of pulse radar ranging, carrier phase ranging, range ambiguity elimination, precision measurement of space targets, and radar measurement and control technology, and particularly relates to a high-precision ranging method for pulse radar based on integer and fractional cycles of the carrier wave. Background Technology
[0002] Pulse radar obtains target range by transmitting pulse signals and measuring the time delay of the target echo relative to the transmitted pulse. The basic relationship of traditional pulse delay ranging is as follows: In the formula, The target distance is measured by pulse delay. The speed of electromagnetic wave propagation. The time delay is the two-way propagation delay of the target echo. Pulse delay ranging has advantages such as long operating range, no integer ambiguity, and mature engineering implementation, and is widely used in systems such as space target ranging, rendezvous and docking, guidance and tracking, space situational awareness, and telemetry and control radar.
[0003] However, the accuracy of traditional pulse delay ranging is primarily limited by the pulse signal bandwidth. For ranging methods such as matched filtering, pulse compression, or envelope center estimation, both range resolution and range estimation accuracy are closely related to signal bandwidth, sampling rate, and echo signal-to-noise ratio. When radar is constrained by size, power consumption, transmit power, antenna aperture, and instantaneous bandwidth, simply increasing the pulse bandwidth or sampling rate to improve ranging accuracy will be limited by engineering bottlenecks. For target measurement tasks requiring centimeter-level, millimeter-level, or even higher precision, traditional pulse envelope ranging can no longer meet the demands of precision ranging.
[0004] Furthermore, existing pulse radars typically treat pulse delay ranging and carrier phase processing as relatively independent functional modules. Pulse delay ranging is mainly used for range detection, range gating, and coarse tracking; carrier phase is typically used for coherent accumulation, Doppler measurement, or phase tracking. These methods do not fully utilize the complementary relationship between the unambiguity of coarse pulse ranging and the high precision of carrier phase. If the integer cycles of the carrier wave can be determined using the coarse pulse range, and the fine position within a half-wavelength range can be determined using the fractional cycles of the carrier phase, then the bandwidth and accuracy bottleneck of traditional pulse envelope ranging can be overcome without significantly increasing the pulse signal bandwidth and sampling rate.
[0005] In other words, the existing technology has the following main shortcomings:
[0006] First, the ranging accuracy of traditional pulse radar is limited by signal bandwidth. Although pulse delay ranging can provide unambiguous absolute distance, its ranging accuracy is mainly limited by pulse signal bandwidth, sampling rate, envelope center estimation accuracy, and echo signal-to-noise ratio. When the radar platform is constrained by instantaneous bandwidth, power consumption, size, and hardware sampling capabilities, it is difficult to improve ranging accuracy simply by increasing the signal bandwidth.
[0007] Second, traditional pulse ranging does not fully utilize the fine distance information corresponding to the carrier phase. The pulse echo contains not only envelope delay information but also carrier phase information. The distance accuracy scale corresponding to the carrier phase is determined by the carrier wavelength and is typically much smaller than the equivalent error scale of pulse envelope ranging. If only the pulse envelope delay is used to output the distance, the carrier phase information in the echo that can be used for precise ranging will be wasted.
[0008] Third, single-carrier-phase ranging suffers from integer-cycle ambiguity. While carrier phase can provide high-precision distances with fractional cycles, it also exhibits integer-cycle ambiguity. Periodicity; when used alone, it can only produce a modulus. In a meaningful sense, distance cannot directly determine the half-wavelength range in which the absolute distance to the target lies.
[0009] Fourth, there is a lack of a unified ranging system between pulse coarse distance and carrier phase fine distance. Existing methods often use pulse coarse distance, distance tracking output, carrier phase and phase tracking results separately in different processing modules, lacking a higher-level ranging method that combines "pulse coarse ranging - carrier integer cycle determination - carrier fractional cycle measurement - absolute distance combination".
[0010] Fifth, directly superimposing the carrier phase onto the pulse range can easily lead to period alignment errors. If the pulse coarse range error is large, or the carrier phase quality is poor, it may cause errors in the selection of the carrier integer cycle, thus resulting in an incorrect final range. Integer multiple jump. Summary of the Invention
[0011] To address the aforementioned problems, this invention provides a high-precision ranging method for pulse radar based on integer and fractional cycles of the carrier wave. While maintaining the unambiguous ranging capability of pulse radar, the target distance is represented as a combination of the distance characterized by the integer cycles of half-wavelength carrier waves and the distance of fractional cycles of carrier waves. By using carrier phase information, the ranging accuracy of pulse radar is improved, thereby forming a carrier phase-enhanced ranging system that differs from simple pulse envelope ranging.
[0012] A high-precision ranging method for pulse radar based on integer and fractional cycles of the carrier wave, the first... The method for obtaining the target distance at each observation time is as follows: The radar transmits pulse signals and receives target echoes. It performs down-conversion, matched filtering, or pulse compression on the target echoes to obtain pre-processed echo signals. Extracting the first peak value from the preprocessed echo signal using matched filtering peak method, envelope center method, or distance tracking loop method. The target unambiguous pulse coarse distance at each observation time ; Unambiguous pulse coarse range for target Smoothing or tracing is performed to obtain a coarse range reference for carrier period alignment. And based on coarse distance reference Determine the integer cycle of the carrier half-wavelength ; The carrier phase observations extracted from the neighborhood of the target echo center are used to determine the first... Carrier fractional-cycle phase at each observation time And according to the carrier fractional-cycle phase Determine the fractional-cycle distance of the carrier ; Based on the integer cycle of the carrier half wavelength Distance from carrier fractional cycles Determine carrier phase enhancement distance ,in, The wavelength of the radar's transmitted pulse signal; right and The consistency of the combined residuals is judged. If the judgment is successful, then... As the first The target distance at each observation time, otherwise... As the first The target distance at each observation time.
[0013] Furthermore, the first The target unambiguous pulse coarse distance at each observation time The calculation method is as follows:
[0014] in, For the first The estimated two-way propagation delay of the echo at each observation time. This represents the speed of electromagnetic wave propagation.
[0015] Furthermore, for unambiguous pulse coarse range targeting... Smoothing or tracing is performed to obtain a coarse range reference for carrier period alignment. The method is as follows:
[0016] in, For coarse distance smoothing operators or tracking operators, For the first The target has unambiguous pulse coarse distance at each observation time.
[0017] Furthermore, at the carrier fractional cycle distance Under unknown conditions, based on coarse distance reference Determine the integer cycle of the carrier half-wavelength The method is as follows:
[0018] in, This indicates rounding to the nearest integer.
[0019] Furthermore, at the carrier fractional cycle distance Under known conditions, based on coarse distance reference Determine the integer cycle of the carrier half-wavelength The method is as follows:
[0020] in, This indicates rounding to the nearest integer.
[0021] Furthermore, the carrier phase observations extracted within the neighborhood of the target echo center are used to determine the first... Carrier fractional-cycle phase at each observation time The method is as follows:
[0022] in, For the first Carrier phase estimates obtained at each observation time The set phase calibration value, Indicates will Normalization to interval .
[0023] Furthermore, based on the carrier fractional-cycle phase Determine the fractional-cycle distance of the carrier The method is as follows:
[0024] in, The range of values is .
[0025] Furthermore, regarding and The method for determining the consistency of combined residuals is as follows: Get and Combined residuals ; Determine the absolute value of the combined residuals Is it less than the consistency threshold? If the structure is true, the consistency check is passed; if the structure is false, the consistency check is not passed.
[0026] Furthermore, consistency threshold The calculation method is as follows:
[0027] in, The standard deviation is the coarse distance reference. The standard deviation of the fractional-cycle phase of the carrier wave. is the confidence coefficient.
[0028] Beneficial effects: This invention provides a high-precision ranging method for pulse radar based on carrier integer cycles and fractional cycles. It unifies the unambiguous coarse ranging capability of pulse radar with the high-precision ranging capability of carrier phase. First, the carrier half-wavelength integer cycle is determined by the unambiguous coarse range of the target pulse. Then, the carrier fractional cycle distance within the half-wavelength interval is determined by the carrier fractional cycle phase. Finally, the target distance is expressed as a combination of the distance represented by the carrier half-wavelength integer cycle and the carrier fractional cycle distance. This improves the ranging accuracy of pulse radar without significantly increasing hardware complexity. In addition, this invention reduces the risk of range jumps caused by phase anomalies, coarse range anomalies, or integer cycle errors through combination consistency judgment and quality control. Attached Figure Description
[0029] Figure 1 The overall flowchart of the high-precision ranging method for pulse radar based on integer and fractional cycles of carrier waves provided by this invention; Figure 2 This is a schematic diagram of the carrier integer cycle and fractional cycle combined ranging provided by the present invention. Detailed Implementation
[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.
[0031] To address the limitations of traditional pulse radar ranging accuracy due to signal bandwidth constraints, the ambiguity of integer cycles in carrier phase ranging alone, and the lack of a unified combined ranging framework, this invention proposes a high-precision ranging method for pulse radar based on integer and fractional cycles of the carrier. This method first obtains an unambiguous range reference using coarse pulse ranging, then determines the integer cycles of the carrier based on the unambiguous range reference, and obtains the fine fractional cycle distance within a half-wavelength range using the fractional cycle phase of the carrier. Finally, the integer and fractional cycles of the carrier are combined to form a high-precision absolute range output.
[0032] It should be noted that, unlike pulse envelope delay, carrier phase contains fine range information determined by the carrier wavelength. Let the radar carrier frequency be... The carrier wavelength is For a single-station radar, the target range changes Phase change with echo carrier The following conditions must be met:
[0033] Therefore, the accuracy of carrier phase ranging is determined by the carrier wavelength, not directly by the pulse envelope bandwidth. For example, when the carrier frequency is... At that time, the carrier wavelength is The half-wavelength range period of a single-station two-way radar is If the carrier phase fractional cycles can be further measured within this half-wavelength period, then finer distance information that is significantly better than pulse envelope ranging can be obtained.
[0034] However, carrier phase has Periodicity. For a single-station two-way radar, the absolute target range can be expressed as:
[0035] In the formula, For an integer number of half-wavelengths of the carrier wave, The carrier phase is the fractional-cycle phase. The above formula shows that carrier phase ranging can be constructed using both the integer half-wavelength and fractional-cycle phases of the carrier. The integer half-wavelength phase is used to determine the half-wavelength range interval in which the target is located, while the fractional-cycle phase is used to determine the fine-grained range position within that interval. If the integer half-wavelength phase is unknown, then the carrier phase can only provide the modulus. Distance in the sense of distance is difficult to form an unambiguous absolute distance on its own.
[0036] Based on this, the present invention proposes a high-precision ranging method for pulse radar based on integer and fractional cycles of the carrier wave. Using the pulse radar echo as input, and building upon the unambiguous distance provided by traditional coarse pulse ranging, the method uses the integer and fractional cycles of the carrier wave's half-wavelength distance provided by the carrier phase as enhanced ranging parameters to obtain the final target distance; specifically, as follows... Figure 1As shown, any number of The method for obtaining the target distance at each observation time is as follows: S1: The radar transmits a pulse signal and receives the target echo. It performs down-conversion, matched filtering, or pulse compression on the target echo to obtain a pre-processed echo signal. The radar transmitted pulse signal can be represented as:
[0037] In the formula, For time, For the launch amplitude, This is a pulse envelope or pulse compression baseband waveform. For carrier frequency, This is the initial phase.
[0038] S2: Extract the first [value] from the preprocessed echo signal using the matched filtering peak method, envelope center method, or distance tracking loop method. The target unambiguous pulse coarse distance at each observation time ; Specifically, assuming the target distance is... Then the first Theoretical echo two-way propagation delay at each observation time for:
[0039] Based on the matched filter peak value, envelope center, range gate tracking, or equivalent method, the theoretical two-way propagation delay of the echo is estimated, and the first... Estimated echo two-way propagation delay at each observation time The target unambiguous pulse coarse range is obtained from the following formula:
[0040] S3: Unambiguous pulse coarse range for target Smoothing or tracing is performed to obtain a coarse range reference for carrier period alignment. And based on coarse distance reference Determine the integer cycle of the carrier half-wavelength ; It should be noted that, to improve coarse range stability, the pulse coarse range can be smoothed or tracked to obtain the first [number] pulse used for determining the integer cycles of the carrier half-wavelength. Coarse distance reference at each observation time :
[0041] In the formula, This is a coarse distance smoothing operator or a tracking operator, which can be a moving average, weighted average, distance tracking loop, Kalman filter, robust filter, or other equivalent method.
[0042] In this invention, Its primary function is not to directly determine the final precise distance, but rather to identify the integer cycles of the carrier half-wavelength. This is because the adjacent distance periods in single-station two-way carrier phase ranging are... Therefore, coarse distance is used to locate the target within the corresponding half-wavelength distance range.
[0043] Specifically, the carrier half-wavelength integer cycle represents the number of half-wavelength cycles contained in the target range. When the carrier fractional cycle range... When the conditions are known, assume the coarse distance reference is... Then, the integer cycles of the carrier half-wavelength can be determined by the following formula:
[0044] In the formula, This indicates rounding to the nearest integer.
[0045] When the carrier fractional frequency distance When the conditions are unknown, the integer cycles of the carrier half-wavelength can also be preliminarily determined based on the coarse distance as follows:
[0046] S4: Determine the first carrier phase observation extracted from the neighborhood of the target echo center. Carrier fractional-cycle phase at each observation time And according to the carrier fractional-cycle phase Determine the fractional-cycle distance of the carrier ; It should be noted that the fractional-cycle carrier phase is used to determine the fine position of the target within a half-wavelength range period. Carrier phase observations are extracted near the target echo center given by the pulse coarse range or range tracking output. Let the... The carrier phase estimates obtained at each observation time are: After system phase calibration, the fractional-cycle phase can be expressed as:
[0047] in, For the first Carrier phase estimates obtained at each observation time The set phase calibration value, Indicates will Normalization to interval .
[0048] The carrier fractional-cycle distance corresponding to the carrier fractional-cycle phase is:
[0049] Its value range is:
[0050] S5: Based on the integer cycles of the carrier half-wavelength Distance from carrier fractional cycles Determine carrier phase enhancement distance ,in, The wavelength of the radar's transmitted pulse signal; It should be noted that, as Figure 2 As shown, if Substitution and further substitute We can obtain:
[0051] The above formula shows that the distance output of the present invention is composed of the distance represented by the integer cycles of the half-wavelength carrier and the distance represented by the fractional cycles of the carrier. Among them, the integer cycles of the half-wavelength carrier ensure that the absolute distance is unambiguous, and the fractional cycles of the carrier ensure high accuracy within the half-wavelength range.
[0052] S6: Yes and The consistency of the combined residuals is judged. If the judgment is successful, then... As the first The target distance at each observation time, otherwise... As the first The target distance at each observation time.
[0053] It should be noted that, in order to reduce distance jumps caused by integer cycle errors or phase anomalies, this invention sets up integer cycle constraints, phase quality judgment, and combination consistency judgment. The combination residual is defined as follows:
[0054] If the following conditions are met:
[0055] If the carrier phase enhancement distance is consistent with the pulse coarse distance, the phase enhancement distance can be output. If this condition is not met, it is considered that there may be an anomaly in the coarse distance, an integer cycle alignment error, or a fractional cycle phase anomaly.
[0056] in, The consistency threshold can be set based on coarse distance error, phase measurement error, and engineering safety margin. For example:
[0057] in, The standard deviation is the coarse distance reference. The standard deviation of the fractional-week phase. is the confidence coefficient.
[0058] In one implementation, the condition is met only when multiple consecutive observation times are satisfied. Only when the phase enhancement distance is confirmed to be effective is the phase enhancement distance confirmed; when multiple consecutive observation times do not meet the requirements. At this time, the system can redetermine the integer cycle, reassess the phase quality, or temporarily output a coarse pulse distance.
[0059] It should be noted that, in addition to the integer cycle determination algorithm and the fractional cycle phase measurement algorithm mentioned above, other algorithms can also be used to obtain the integer cycle and fractional cycle phase, which will not be elaborated upon here. The key point of this invention is that, in the pulse radar system, the pulse coarse range provides unambiguous constraints, and the carrier half-wavelength integer cycle and fractional cycle distance together constitute a high-precision range output, thereby breaking through the bandwidth accuracy bottleneck of simple pulse envelope ranging.
[0060] Therefore, compared with simple pulse delay ranging, this invention no longer relies solely on pulse envelope delay information, but further utilizes the echo carrier phase to construct integer and fractional cycle distances. Thus, it can overcome the accuracy bottleneck of traditional pulse ranging, which is mainly limited by signal bandwidth. Compared with single carrier phase ranging, this invention uses pulse coarse distance to provide ambiguity-free constraints, thereby determining the integer cycle of the carrier, enabling the carrier phase ranging results to be more precise. The range is extended to absolute range. Compared with high-precision ranging schemes that rely on increased bandwidth and higher sampling rates, this invention mainly utilizes carrier phase information in existing pulse echoes to improve ranging accuracy. It has lower additional requirements for instantaneous bandwidth and sampling rate, making it suitable for space-based, miniaturized, low-power, and long-range radar systems.
[0061] In summary, this invention provides a high-precision ranging method for pulse radar based on carrier integer cycles and fractional cycles. It overcomes the limitations of traditional pulse radar bandwidth ranging accuracy bottlenecks by employing carrier phase enhancement ranging. A ranging framework is constructed that utilizes coarse pulse ranging to provide an unambiguous distance reference, uses carrier integer cycles to determine a half-wavelength distance interval, and uses carrier fractional cycles to determine the fine position within the interval. Based on this framework under coarse range constraints, the target distance is represented as a combination of the distance characterized by carrier half-wavelength integer cycles and the carrier fractional cycle distance. In other words, it proposes a method based on... The pulse radar carrier phase enhancement range output format represents the carrier phase ranging method, which transforms the mode-based range measurement from a linear method. The distance is extended to absolute distance, and the ranging accuracy is improved by using carrier phase information without significantly increasing the pulse signal bandwidth and sampling rate.
[0062] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.
Claims
1. A high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave, characterized in that, No. The method for obtaining the target distance at each observation time is as follows: The radar transmits pulse signals and receives target echoes. It performs down-conversion, matched filtering, or pulse compression on the target echoes to obtain pre-processed echo signals. Extracting the first peak value from the preprocessed echo signal using matched filtering peak method, envelope center method, or distance tracking loop method. The target unambiguous pulse coarse distance at each observation time ; Unambiguous pulse coarse range for target Smoothing or tracing is performed to obtain a coarse range reference for carrier period alignment. And based on coarse distance reference Determine the integer cycle of the carrier half-wavelength ; The carrier phase observations extracted from the neighborhood of the target echo center are used to determine the first... Carrier fractional-cycle phase at each observation time And according to the carrier fractional-cycle phase Determine the fractional-cycle distance of the carrier ; Based on the integer cycle of the carrier half wavelength Distance from carrier fractional cycles Determine carrier phase enhancement distance ,in, The wavelength of the radar's transmitted pulse signal; right and The consistency of the combined residuals is judged. If the judgment is successful, then... As the first The target distance at each observation time, otherwise... As the first The target distance at each observation time.
2. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, No. The target unambiguous pulse coarse distance at each observation time The calculation method is as follows: in, For the first The estimated two-way propagation delay of the echo at each observation time. This represents the speed of electromagnetic wave propagation.
3. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, Unambiguous pulse coarse range for target Smoothing or tracing is performed to obtain a coarse range reference for carrier period alignment. The method is as follows: in, For coarse distance smoothing operators or tracking operators, For the first The target has unambiguous pulse coarse distance at each observation time.
4. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, Carrier fractional cycle distance Under unknown conditions, based on coarse distance reference Determine the integer cycle of the carrier half-wavelength The method is as follows: in, This indicates rounding to the nearest integer.
5. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, Carrier fractional cycle distance Under known conditions, based on coarse distance reference Determine the integer cycle of the carrier half-wavelength The method is as follows: in, This indicates rounding to the nearest integer.
6. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, The carrier phase observations extracted from the neighborhood of the target echo center are used to determine the first... Carrier fractional-cycle phase at each observation time The method is as follows: in, For the first Carrier phase estimates obtained at each observation time The set phase calibration value, Indicates will Normalization to interval .
7. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, Based on the carrier fractional cycle phase Determine the fractional-cycle distance of the carrier The method is as follows: in, The range of values is .
8. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 1, characterized in that, right and The method for determining the consistency of combined residuals is as follows: Get and Combined residuals ; Determine the absolute value of the combined residuals Is it less than the consistency threshold? If the structure is true, the consistency check is passed; if the structure is false, the consistency check is not passed.
9. The high-precision ranging method for pulse radar based on integer and fractional cycles of a carrier wave as described in claim 8, characterized in that, Consistency threshold The calculation method is as follows: in, The standard deviation is the coarse distance reference. The standard deviation of the fractional-cycle phase of the carrier wave. is the confidence coefficient.