A wireless ranging and clock synchronization method for aerial search and rescue scenarios

Abstract

The application provides a wireless ranging and clock synchronization method for an aviation search and rescue scene, relates to the fields of spread spectrum communication and wireless ranging, and comprises the following steps: determining a relative motion state, performing one-way two-way ranging between two nodes, obtaining clock offset estimation and clock frequency offset estimation by using a least square method, and processing according to different motion states; when the master node and the slave node are in a high-speed radial motion state, the slave node sends a spread spectrum signal to the master node, pseudo-range observation and carrier phase observation are obtained; the pseudo-range observation is compensated and calculated based on the clock offset estimation, the carrier distance increment is compensated and calculated based on the clock frequency offset estimation; the compensated pseudo-range observation and the compensated carrier distance increment are used for carrier smoothing pseudo-range recursive processing, and a ranging result is obtained. Through the above method, the cumulative errors of clock offset and clock frequency offset are suppressed in a unified smoothing framework, and the ranging accuracy under the high-speed motion condition is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of spread spectrum communication and wireless ranging technology, specifically to a wireless ranging and clock synchronization method for aviation search and rescue scenarios. Background Technology

[0002] In aerial search and rescue missions, determining the location of the target or emergency beacon typically requires measuring the distance between the search and rescue platform and the target node. Spread spectrum communication technology, due to its strong anti-interference capabilities, long communication range, and good security, is widely used in communication and ranging within aerial search and rescue systems. By measuring the propagation delay of the spread spectrum signal, the distance between the moving platform and the target node can be estimated, thus providing fundamental information for subsequent positioning and search and rescue operations.

[0003] Currently, commonly used ranging methods in spread spectrum ranging systems include one-way pseudorange measurement and two-way ranging. One-way pseudorange measurement requires high-precision clock synchronization, making the system implementation complex. Two-way ranging, on the other hand, utilizes signal interaction between master and slave nodes, which can eliminate the influence of clock deviation on the ranging results to some extent, thus gaining wider application in practical systems. For example, two-way ranging typically involves the master node sending a ranging request signal, and the slave node receiving it and returning a response signal. By recording the transmission and reception timestamps of the signals, the signal propagation delay is calculated, thereby obtaining the distance between the master and slave nodes.

[0004] However, in real-world aerial search and rescue scenarios, the relative motion between the search and rescue platform and the target node can constantly change. When the system is in different motion states, existing ranging methods struggle to simultaneously ensure ranging accuracy and system stability. For example, under relatively stable motion conditions, multiple ranging measurements followed by estimation can effectively improve ranging accuracy; however, under conditions of rapid relative motion or significant distance changes, traditional ranging methods may be affected by motion errors, thus reducing the stability and accuracy of the ranging results.

[0005] Furthermore, existing methods struggle to suppress the cumulative drift of clock frequency offset during the smoothing recursion process. On one hand, the original pseudorange observations contain systematic errors introduced by both clock offset and clock skew, which cannot be automatically eliminated by smoothing alone. On the other hand, clock frequency offset also enters the carrier increment of adjacent epochs, resulting in cumulative drift during the recursion process. Therefore, the ranging accuracy is significantly limited by the influence of cumulative drift. Summary of the Invention

[0006] To reduce the cumulative errors of clock offset and clock frequency offset and improve ranging accuracy under high-speed motion conditions, this invention provides a wireless ranging and clock synchronization method for aviation search and rescue scenarios, the method comprising:

[0007] Step S1: Determine the relative motion state between the master node and the slave node;

[0008] Step S2: Perform one-sided two-way ranging between the master node and the slave node, and process the data using the least squares method according to the preset observation equation to obtain the parameter estimation results based on the observation equation. The parameter estimation results include the clock offset estimate, clock frequency offset estimate, and propagation delay estimate between the master node and the slave node.

[0009] Step S3: When the master node and slave node are in a non-high-speed radial motion state, calculate the distance between the master node and slave node based on the propagation delay estimate, and calibrate the local clock of the master node and the local clock of the slave node based on the clock offset estimate, so that the local clock of the master node and the local clock of the slave node reach a synchronized state.

[0010] Step S4: When the master node and slave node are in a high-speed radial motion state, execute the following steps S4.1-S4.4:

[0011] Step S4.1: Send spread spectrum signal from the slave node to the master node to obtain pseudorange observations and carrier phase observations;

[0012] Step S4.2: Based on the clock bias estimate, the pseudorange observation is compensated according to the following formula to obtain the compensated pseudorange observation:

[0013] ,

[0014] in, This represents the compensated pseudorange observation value corresponding to the k-th epoch; This represents the pseudorange observation value corresponding to the k-th epoch when the slave node sends the spread spectrum signal to the master node. represents the clock deflection estimate, and c represents the speed of light;

[0015] Step S4.3: Using the clock frequency offset estimate, calculate the compensation carrier distance increment according to the following formula to obtain the compensated carrier distance increment:

[0016] ,

[0017] in, This represents the compensation carrier distance increment corresponding to the k-th epoch; The wavelength of the carrier signal. and This represents the carrier phase observation values ​​at the (k-1)th and kth epochs, respectively, when the slave node sends the spread spectrum signal to the master node. This represents the estimated clock frequency offset. Let represent the time interval between the k-th epoch and the (k-1)-th epoch, and let c represent the speed of light;

[0018] Step S4.4: Based on the compensated pseudorange observations and the compensated carrier distance increment, perform carrier smoothing pseudorange recursion processing according to the following formula to obtain the ranging result between the master node and the slave node:

[0019] ,

[0020] in, and These represent the smoothed output distances corresponding to the k-th epoch and the (k-1)-th epoch, respectively; M represents the smoothing window length. This represents the compensated pseudorange observation corresponding to the k-th epoch. This represents the compensation carrier distance increment corresponding to the kth epoch.

[0021] Optionally, the observation equation is expressed according to the following formula:

[0022] ,

[0023] in, This represents the difference between the slave node's receiving time and the master node's sending local timestamp when the master node sends the ranging signal to the slave node in the k-th epoch. This represents the difference between the time the master node receives the ranging signal and the time the slave node sends the local timestamp when the slave node sends the ranging signal to the master node in the k-th epoch. This represents the local timestamp sent by the master node when it sends a ranging signal to the slave node in the k-th epoch. This represents the local timestamp of the slave node when it sends a ranging signal to the master node in the kth epoch. Indicates the propagation delay. This indicates the clock offset of the slave node relative to the master node. This indicates the clock frequency offset of the slave node relative to the master node.

[0024] Optionally, step S2 includes:

[0025] One-way bidirectional ranging is performed between the master node and the slave node. The parameters are estimated using the least squares method according to a preset observation equation and an optimization objective based on the observation equation. The optimization objective is expressed by the following formula:

[0026] ,

[0027] in, Indicate the optimization objective; , , .

[0028] Optionally, step S1 includes:

[0029] The master node sends a spread spectrum ranging request signal to the slave node, the spread spectrum ranging request signal including a Barker code frame header;

[0030] The slave node receives the spread spectrum ranging request signal, performs frame synchronization, and enters the ranging response state.

[0031] The master node and slave node perform multiple one-sided bidirectional distance measurements to obtain the distance change value between the nodes;

[0032] The relative motion state between the master node and the slave node is determined based on the distance change value.

[0033] Furthermore, the present invention also proposes an electronic device and a readable storage medium:

[0034] An electronic device includes a processor and a memory, the memory being used to store one or more programs; when the one or more programs are executed by the processor, the above-described method is implemented.

[0035] A readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0036] The present invention has the following advantages:

[0037] This invention provides a wireless ranging and clock synchronization method for aviation search and rescue scenarios. After acquiring the relative motion state between the master node and the slave node, unilateral bidirectional ranging is performed between the master and slave nodes, and the least squares method is used to obtain parameter estimation results based on the observation equation. When the master and slave nodes are in a non-high-speed radial motion state, the distance between the master and slave nodes is calculated based on the propagation delay estimate, and adjusted based on the clock offset estimate to synchronize the clocks of the master and slave nodes. When the master and slave nodes are in a high-speed radial motion state, the slave node sends a spread spectrum signal to the master node to acquire pseudorange observations and carrier phase observations. Based on the clock offset estimate, the pseudorange observations are compensated to obtain compensated pseudorange observations. Based on the clock offset estimate, the carrier distance increment is compensated to obtain the compensated carrier distance increment. Based on the compensated pseudorange observations and the compensated carrier distance increment, carrier smoothing pseudorange recursion is performed to obtain the ranging result between the master and slave nodes.

[0038] By using the estimated clock offset to correct the code pseudorange observations, the deterministic systematic bias caused by the initial clock offset and drift in the original code pseudorange observations is effectively eliminated. The estimated clock frequency offset is then used to compensate for the integral Doppler observations in the carrier smoothing recursion, effectively removing the range drift equivalent to local clock frequency mismatch. This achieves simultaneous suppression of clock offset and frequency offset accumulation errors within a unified smoothing framework, effectively improving ranging accuracy under high-speed motion conditions. Attached Figure Description

[0039] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0040] Figure 1 This is a flowchart illustrating the steps of a wireless ranging and clock synchronization method for an aviation search and rescue scenario proposed in an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram illustrating the timestamp exchange during unilateral bidirectional ranging between master and slave nodes, as provided by the present invention. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0043] Reference Figure 1 The present invention provides a flowchart of the steps of a wireless ranging and clock synchronization method for aviation search and rescue scenarios, as proposed in an embodiment of the present invention, specifically including:

[0044] Step S1: Determine the relative motion state between the master node and the slave node.

[0045] The master node and slave nodes include, but are not limited to, search and rescue platforms, motion platforms, and target nodes. The relative motion state between the master node and slave nodes includes high-speed radial motion and non-high-speed radial motion, which can be determined by the distance change per unit time or by measuring the corresponding distance change multiple times. Specifically, it can include:

[0046] The master node sends a spread spectrum ranging request signal to the slave node, the spread spectrum ranging request signal including a Barker code frame header;

[0047] The slave node receives the spread spectrum ranging request signal, performs frame synchronization, and enters the ranging response state.

[0048] The master node and slave node perform multiple one-sided bidirectional distance measurements to obtain the distance change value between the nodes;

[0049] The relative motion state between the master node and the slave node is determined based on the distance change value.

[0050] As an example, the specific process is as follows: The master node first sends a spread spectrum ranging request signal to the slave nodes to initiate the distance measurement process between the nodes. The spread spectrum ranging request signal can be spread spectrum modulated using a pseudo-random sequence. The signal frame structure includes a Barker code header, ranging control information, and timestamp information. The Barker code sequence is used for fast synchronization and header detection at the receiver to improve the reliability of signal detection; the ranging control information is used to instruct the slave nodes to enter ranging response mode. The master node records the local transmission timestamp when sending the spread spectrum ranging request signal for subsequent distance calculation and clock synchronization processing.

[0051] By employing spread spectrum modulation, the system's anti-interference capability and ranging stability can be improved, making it suitable for complex wireless propagation environments such as air search and rescue.

[0052] After receiving the spread spectrum ranging request signal from the master node, the slave node first captures and synchronizes the Barker code frame header to determine the signal arrival time. Once frame synchronization is complete, the slave node reads its local clock and records the received timestamp. Subsequently, the slave node enters the ranging response state based on the control information in the ranging request signal and prepares to send a ranging response signal to the master node.

[0053] After completing the initial signal exchange, the master node and slave node perform multiple consecutive one-way bidirectional ranging measurements. Specifically, the master node sends a ranging signal, the slave node receives it and sends a response signal within a short period of time, and the master node then receives the response signal and records the timestamp.

[0054] In this embodiment, the system performs multiple consecutive unilateral bidirectional distance measurements, such as 3 or 5 times, the specific number depending on the situation. By comparing the continuous distance measurement results, the distance changes between nodes can be obtained, and the movement state of the nodes can be determined based on the distance changes. Taking three measurements as an example, if the distance change between two or three consecutive distance measurements reaches or exceeds a preset threshold, it is determined that there is a large radial movement speed between the master node and the slave node; if the distance change is less than the threshold, it is determined that the nodes are in a non-high-speed radial movement state. The preset threshold can be determined according to the actual situation.

[0055] Step S2: Perform one-sided two-way ranging between the master node and the slave node, and process the data using the least squares method according to the preset observation equation to obtain the parameter estimation results based on the observation equation. The parameter estimation results include the clock offset estimate, clock frequency offset estimate, and propagation delay estimate between the master node and the slave node.

[0056] The observation equation can be derived based on either time difference or time. Taking the observation equation derived based on time difference as an example, the preset observation equation can be expressed as:

[0057] (1)

[0058] in, This represents the difference between the slave node's receiving time and the master node's sending local timestamp when the master node sends the ranging signal to the slave node in the k-th epoch. This represents the difference between the time the master node receives the ranging signal and the time the slave node sends the local timestamp when the slave node sends the ranging signal to the master node in the k-th epoch. This represents the local timestamp sent by the master node when it sends a ranging signal to the slave node in the k-th epoch. This represents the local timestamp of the slave node when it sends a ranging signal to the master node in the kth epoch. Indicates the propagation delay. This indicates the clock offset of the slave node relative to the master node. This indicates the clock frequency offset of the slave node relative to the master node.

[0059] Taking master node A as a reference, and given that slave node B's local clock has clock offset and clock frequency offset, the relationship between slave node time and master node time can be expressed as:

[0060] (2)

[0061] in, The time of the primary node. For the time of the node, This is the clock offset of the slave node relative to the master node. The clock skew of the slave node relative to the master node is typically... The unit is ppm.

[0062] Specifically, such as Figure 2 The diagram provided by this invention illustrates the timestamp exchange during unilateral bidirectional ranging between master and slave nodes. Here, t represents a time point. This represents the propagation delay between master node A and slave node B. This indicates the clock offset of slave node B relative to master node A; the master and slave nodes perform multiple one-way bidirectional ranging and timestamp exchanges. In the k-th ranging process, i.e., the k-th epoch, master node A sends a local timestamp of... Receive signal from node B, reception time is Due to the existence of propagation delay 、Clock offset and clock frequency offset , then we have:

[0063] , (3)

[0064] The slave node B sends a response signal at the time of , and the master node A receives the signal at the time of , then we have:

[0065] , (4)

[0066] Since the clock frequency offset is usually much less than 1, a first-order approximation can be made:

[0067] , (5)

[0068] Then the observation equation can be approximately expressed as the following formula:

[0069] , (6)

[0070] , (7)

[0071] Define and as follows:

[0072] , (8)

[0073] , (9)

[0074] Then the observation equation shown in formula (1) can be obtained:

[0075] ,

[0076] When K ranging measurements are performed, multiple sets of observation equations can be obtained, where , , , and then the least squares method is used to obtain the clock offset estimate value , the clock frequency offset estimate value and the propagation delay estimate value , that is:[[ID=8​​​​​​ Let 2-norm be the criterion, then the optimization objective based on the observation equation is... It can be represented as:

[0079] (11)

[0080] Formula (11) calculates the clock offset, clock frequency offset, and propagation delay estimates between the master and slave nodes by minimizing the optimization objective. This enables effective quantization of clock offset and clock frequency offset, thereby achieving clock synchronization. Consequently, it provides accurate error stripping for subsequent pseudorange correction and carrier phase increment compensation, improving ranging accuracy. Alternatively, the optimization objective can also use other metrics such as the 1-norm, which can be determined according to the actual situation.

[0081] Step S3: When the master node and slave node are in a non-high-speed radial motion state, calculate the distance between the master node and slave node based on the propagation delay estimate, and calibrate the local clock of the master node and the local clock of the slave node based on the clock offset estimate, so that the local clock of the master node and the local clock of the slave node reach a synchronized state.

[0082] Reference Figure 1 When the master node and slave node are in a non-high-speed radial motion state, the propagation delay can be estimated. The distance between nodes can be calculated directly. , The speed of light is used, and the resulting clock deflection estimate is used. The compensation is transferred to the slave node, thereby synchronizing the slave node clock with the master node clock.

[0083] Step S4: When the master node and slave node are in a high-speed radial motion state, execute the following steps S4.1-S4.4:

[0084] Step S4.1: Send spread spectrum signal from the slave node to the master node to obtain pseudorange observations and carrier phase observations.

[0085] If high-speed radial motion occurs, the slave node sends a continuous spread spectrum signal, periodically carrying the local time of the transmitting slave device. The master node receives and records the carrier phase observations of multiple epochs and its own local timestamp, thereby calculating the code pseudorange observation based on the local timestamp. This invention refers to the pseudorange observation as the pseudorange observation, which provides a data basis for subsequent suppression of clock offset and cumulative drift of clock frequency offset in the smoothing recursion process.

[0086] Step S4.2: Based on the clock bias estimate, the pseudorange observation is compensated according to the following formula to obtain the compensated pseudorange observation:

[0087] (12)

[0088] in, This represents the compensated pseudorange observation value corresponding to the k-th epoch; This represents the pseudorange observation value corresponding to the k-th epoch when the slave node sends the spread spectrum signal to the master node. denoted by , where c represents the clock bias estimate and c represents the speed of light.

[0089] For the pseudorange observation value corresponding to the kth epoch Subtract the predicted clock offset value in the corresponding distance domain from it, which is the clock offset estimate output in step S2. Then the compensated pseudorange observation can be obtained. After the above compensation, It contains purer true geometric distance information and residual observation noise, while the original one existed The deterministic systematic bias caused by the initial clock bias and drift is effectively removed, which provides an unbiased or low-biased absolute constraint for subsequent smoothing.

[0090] Step S4.3: Using the clock frequency offset estimate, calculate the compensation carrier distance increment according to the following formula to obtain the compensated carrier distance increment:

[0091] (13)

[0092] in, This represents the compensation carrier distance increment corresponding to the k-th epoch; The wavelength of the carrier signal. and This represents the carrier phase observation values ​​at the (k-1)th and kth epochs, respectively, when the slave node sends the spread spectrum signal to the master node. This represents the estimated clock frequency offset. The time interval between the k-th epoch and the (k-1)-th epoch recorded by the master node is represented by c, which represents the speed of light.

[0093] Under ideal clock conditions, the carrier distance increment between adjacent epochs, i.e., the integral Doppler observation value. It primarily reflects high-precision changes in actual geometric distance. However, in systems with clock bias, this increment incorporates a time drift term. If subsequent ranging calculations are performed directly based on the original carrier increment, the smoothed output will exhibit a non-negligible time drift as the observation epoch increases, reducing the accuracy of the ranging results.

[0094] Therefore, the present invention is based on the clock frequency offset estimate obtained in step S2. The clock drift compensation term is explicitly subtracted from the carrier increment to construct the compensated integral Doppler observation, which is the compensated carrier distance increment. This compensation increment effectively removes the distance drift caused by local clock frequency mismatch, enabling it to more realistically reflect low-noise geometric distance variations.

[0095] Step S4.4: Based on the compensated pseudorange observations and the compensated carrier distance increment, perform carrier smoothing pseudorange recursion processing according to the following formula to obtain the ranging result between the master node and the slave node:

[0096] (14)

[0097] in, and These represent the smoothed output distances corresponding to the k-th epoch and the (k-1)-th epoch, respectively; M represents the smoothing window length. This represents the compensated pseudorange observation corresponding to the k-th epoch. This represents the compensation carrier distance increment corresponding to the kth epoch.

[0098] After obtaining the compensated pseudorange observation values Compensation carrier distance increment Subsequently, this invention performs ranging calculations based on a carrier smoothing pseudorange recursion method.

[0099] Carrier smoothing pseudorange utilizes the complementary characteristics of code pseudorange observation and carrier phase observation to improve ranging accuracy. Code pseudorange observation can provide absolute distance information, but its random noise is relatively large; carrier phase observation has lower noise and better short-time continuity, but its absolute observation value contains integer ambiguity, making it difficult to use directly as absolute distance. Let the true geometric distance at the k-th epoch be... pseudo-range observation It can be represented as:

[0100] (15)

[0101] Carrier phase observations, converted to distance, can be expressed as: :

[0102] (16)

[0103] Where λ is the wavelength of the carrier signal, and N is the integer ambiguity. and Let N be the code pseudorange noise and carrier phase noise corresponding to the k-th epoch, respectively. In the absence of cycle slips, the integer ambiguity N remains unchanged between adjacent epochs; therefore, the difference between carrier phase observations of adjacent epochs yields:

[0104] (17)

[0105] Since carrier phase noise is typically smaller than code pseudorange noise, the carrier phase difference component It can reflect the distance changes between adjacent epochs more accurately, that is:

[0106] (18)

[0107] Therefore, the smoothed output distance from the previous epoch can be utilized. The carrier distance increment of the current epoch predicts the current distance. Its prediction term can be written as:

[0108] (19)

[0109] To avoid error accumulation caused by long-term carrier phase recursion, and to utilize code pseudorange to provide absolute distance constraints, the predicted value can be weighted and corrected by incorporating the current epoch code pseudorange observation, thus obtaining the smoothed output distance at the k-th epoch. :

[0110] (20)

[0111] The above recursive structure retains the absolute distance constraint of the code pseudorange and utilizes the high-precision change information of the carrier phase increment, thereby reducing pseudorange random noise and improving the continuity and stability of the distance output.

[0112] When the master and slave nodes are in a high-speed radial motion state, the slave node transmits a continuous spread spectrum signal, periodically carrying the local time of the transmitting slave device. The master node receives and records the carrier phase observations over multiple epochs and its own local timestamp. Subsequently, based on the above carrier smoothing pseudorange recursion, and further combining the dual-branch clock compensation results, clock compensation is performed on the code pseudorange observations and carrier phase distance increments respectively, thereby obtaining high-precision distance observations.

[0113] Specifically, after completing the clock compensation for the code pseudorange observations and carrier distance increments, the pseudorange observations will be compensated. Compensation carrier distance increment Substituting into the carrier smoothing pseudorange recursive structure, we can obtain the clock-assisted carrier smoothing pseudorange recursive equation shown in formula (14), and expand it to obtain:

[0114] ,(twenty one)

[0115] In formula (21), the compensated pseudorange observation is used to provide an absolute range reference, and the compensated carrier range increment is used to provide a high-precision range variation constraint. By recursively weighting and fusing the two, the range drift caused by local clock frequency mismatch can be reduced while suppressing pseudorange random noise, thereby improving the stability and rationality of range estimation in high-speed relative motion scenarios.

[0116] In summary, this invention provides a wireless ranging and clock synchronization method for aviation search and rescue scenarios. After acquiring the relative motion state between the master node and the slave node, unilateral bidirectional ranging is performed between the master and slave nodes, and the least squares method is used to obtain parameter estimation results based on the observation equation. When the master and slave nodes are in a non-high-speed radial motion state, the distance between the master and slave nodes is calculated based on the propagation delay estimate, and adjusted based on the clock offset estimate to synchronize the clocks of the master and slave nodes. When the master and slave nodes are in a high-speed radial motion state, the slave node sends a spread spectrum signal to the master node to acquire pseudorange observations and carrier phase observations. Based on the clock offset estimate, the pseudorange observations are compensated to obtain compensated pseudorange observations. Based on the clock offset estimate, the carrier distance increment is compensated to obtain the compensated carrier distance increment. Based on the compensated pseudorange observations and the compensated carrier distance increment, carrier smoothing pseudorange recursion is performed to obtain the ranging result between the master and slave nodes.

[0117] By using the estimated clock offset to correct the code pseudorange observations, the deterministic systematic bias caused by the initial clock offset and drift in the original code pseudorange observations is effectively eliminated. The estimated clock frequency offset is then used to compensate for the integral Doppler observations in the carrier smoothing recursion, effectively removing the range drift equivalent to local clock frequency mismatch. This achieves simultaneous suppression of clock offset and frequency offset accumulation errors within a unified smoothing framework, effectively improving ranging accuracy under high-speed motion conditions.

[0118] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A wireless ranging and clock synchronization method for aviation search and rescue scenarios, characterized in that, The method includes: Step S1: Determine the relative motion state between the master node and the slave node; Step S2: Perform one-sided two-way ranging between the master node and the slave node, and process the data using the least squares method according to the preset observation equation to obtain the parameter estimation results based on the observation equation. The parameter estimation results include the clock offset estimate, clock frequency offset estimate, and propagation delay estimate between the master node and the slave node. Step S3: When the master node and slave node are in a non-high-speed radial motion state, calculate the distance between the master node and slave node based on the propagation delay estimate, and calibrate the local clock of the master node and the local clock of the slave node based on the clock offset estimate, so that the local clock of the master node and the local clock of the slave node reach a synchronized state. Step S4: When the master node and slave node are in a high-speed radial motion state, execute the following steps S4.1-S4.4: Step S4.1: Send spread spectrum signal from the slave node to the master node to obtain pseudorange observations and carrier phase observations; Step S4.2: Based on the clock bias estimate, the pseudorange observation is compensated according to the following formula to obtain the compensated pseudorange observation: ， in, This represents the compensated pseudorange observation value corresponding to the k-th epoch; This represents the pseudorange observation value corresponding to the k-th epoch when the slave node sends the spread spectrum signal to the master node. represents the clock deflection estimate, and c represents the speed of light; Step S4.3: Using the clock frequency offset estimate, calculate the compensation carrier distance increment according to the following formula to obtain the compensated carrier distance increment: ， in, This represents the compensation carrier distance increment corresponding to the k-th epoch; The wavelength of the carrier signal. and This represents the carrier phase observation values ​​at the (k-1)th and kth epochs, respectively, when the slave node sends the spread spectrum signal to the master node. This represents the estimated clock frequency offset. Let represent the time interval between the k-th epoch and the (k-1)-th epoch, and let c represent the speed of light; Step S4.4: Based on the compensated pseudorange observations and the compensated carrier distance increment, perform carrier smoothing pseudorange recursion processing according to the following formula to obtain the ranging result between the master node and the slave node: ， in, and These represent the smoothed output distances corresponding to the k-th epoch and the (k-1)-th epoch, respectively; M represents the smoothing window length. This represents the compensated pseudorange observation corresponding to the k-th epoch. This represents the compensation carrier distance increment corresponding to the kth epoch.

2. The method according to claim 1, characterized in that, The observation equation is expressed by the following formula: ， in, This represents the difference between the slave node's receiving time and the master node's sending local timestamp when the master node sends the ranging signal to the slave node in the k-th epoch. This represents the difference between the time the master node receives the ranging signal and the time the slave node sends the local timestamp when the slave node sends the ranging signal to the master node in the k-th epoch. This represents the local timestamp sent by the master node when it sends a ranging signal to the slave node in the k-th epoch. This represents the local timestamp of the slave node when it sends a ranging signal to the master node in the kth epoch. Indicates the propagation delay. This indicates the clock offset of the slave node relative to the master node. This indicates the clock frequency offset of the slave node relative to the master node.

3. The method according to claim 2, characterized in that, Step S2 includes: One-way bidirectional ranging is performed between the master node and the slave node. The parameters are estimated using the least squares method according to a preset observation equation and an optimization objective based on the observation equation. The optimization objective is expressed by the following formula: ， in, Indicate the optimization objective; , , .

4. The method according to claim 1, characterized in that, Step S1 includes: The master node sends a spread spectrum ranging request signal to the slave node, the spread spectrum ranging request signal including a Barker code frame header; The slave node receives the spread spectrum ranging request signal, performs frame synchronization, and enters the ranging response state. The master node and slave node perform multiple one-sided bidirectional distance measurements to obtain the distance change value between the nodes; The relative motion state between the master node and the slave node is determined based on the distance change value.

5. An electronic device, comprising a processor and a memory, wherein the memory is used to store one or more programs; characterized in that: When the processor executes the one or more programs, it implements the method of any one of claims 1 to 4.

6. A readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the method described in any one of claims 1 to 4.

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