A high-precision distance measurement system and method based on beat sampling

Abstract

The present invention provides a high-precision ranging system and method based on beat sampling, comprising two completely identical terminals; wherein the two terminals both comprise: a ranging frame sending unit for generating a ranging frame and sending the ranging frame to another terminal; a ranging frame receiving unit for receiving a ranging frame feedback signal including a ranging frame sending time calculated by the other terminal, and obtaining the time when the ranging frame calculated by the current terminal arrives at the other terminal; an ADC sampling calculation module for obtaining a frequency difference and a phase difference between a sending clock and a receiving clock through frequency and phase discrimination; a ranging frame sending time calculation module for obtaining a ranging frame sending time calculation value; and a ranging calculation module for obtaining a ranging calculation value and a distance between the two terminals according to the ranging frame arrival time and the ranging frame sending time calculation value calculated by the other terminal in the ranging frame feedback signal.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication distance measurement, and in particular to a high-precision distance measurement system and method based on beat sampling. Background Art

[0002] With the continuous development of aerospace technology and communication technology, countries are studying the space network that integrates air, space and land. The launch of the Starlink project also confirms this trend. For the integrated network of air, space and land, it has the characteristics of global coverage, flexibility, and fast transmission rate. It will inevitably become a new hot research direction in the future. The integrated network of air, space and land has precise requirements for the position of satellites. Only by ensuring that each satellite is in the correct position can the efficient operation of the integrated network of air, space and land be guaranteed. Therefore, it is necessary for satellites to be able to continuously confirm the position relationship between satellites and between satellites and the ground while communicating, which requires a communication system with high-precision ranging function.

[0003] However, high-speed communication in space is bound to be affected by the Doppler effect. The common solution is to estimate the frequency deviation value caused by the Doppler effect at the receiving end, and then use equalization or synchronization to compensate. However, the existing measurement method has high requirements for the clock source. The clock frequency in space will fluctuate greatly due to the Doppler effect. It is very necessary to eliminate the influence of the Doppler effect when restoring the receiving clock frequency and improve the accuracy of ranging. Summary of the invention

[0004] In view of this, the present invention proposes a high-precision ranging system and method based on beat sampling, which can reduce the requirements for the clock source and reduce the complexity of the time-frequency system.

[0005] The technical solution of the present invention is implemented as follows: On the one hand, the present invention provides a high-precision ranging system based on beat sampling, comprising two identical terminals; wherein the two terminals both include

[0006] A ranging frame sending unit (100) is used to generate a ranging frame and send it to another terminal; the ranging frame sending unit (100) also outputs a sending clock;

[0007] A ranging frame receiving unit (200) is used to receive a ranging frame feedback signal including a ranging frame transmission time calculated by another terminal, and obtain the time when the ranging frame calculated by the current terminal arrives at the other terminal; the ranging frame receiving unit (200) also outputs a receiving clock;

[0008] The ADC sampling calculation module (117) is used to obtain a sending clock output by a ranging frame sending unit (100) and a receiving clock output by a ranging frame receiving unit (200), and to perform beat sampling on the receiving clock based on the sending clock; and to obtain a frequency difference and a phase difference between the sending clock and the receiving clock by frequency and phase discrimination;

[0009] A ranging frame sending time calculation module (118) is used to obtain the ranging frame sending time calculated by another terminal from the ranging frame feedback signal, and the sending clock frequency, receiving clock frequency, and frequency difference and phase difference obtained from the ADC sampling calculation module (117), to obtain a calculated value of the ranging frame sending time;

[0010] The ranging calculation module (119) obtains a ranging calculation value according to a ranging frame arrival time and a ranging frame transmission time calculated by another terminal in a ranging frame feedback signal.

[0011] On the basis of the above technical solution, preferably, the ranging frame sending unit (100) comprises

[0012] A local ranging frame sending time calculation module (111), used to calculate the sending time of the current ranging frame of the current terminal;

[0013] The data frame assembly module (112) is used to integrate the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module (111) and the pseudo-range value calculated by the current terminal according to the format of the data frame to obtain a ranging frame.

[0014] Preferably, the ranging frame sending unit (100) further comprises a high-speed serial sending interface (113); the high-speed serial sending interface (113) is used to convert the ranging frame integrated by the data frame framing module (112) into a serial data stream for output to another terminal, and output a sending clock to the ADC sampling calculation module (117).

[0015] Further preferably, the ranging frame receiving unit (200) comprises

[0016] A data frame de-framing module (115) is used to receive input from another terminal, perform de-framing and split the frame, and obtain the ranging frame sending time calculated by the other terminal and the pseudo-range value calculated by the other terminal;

[0017] The ranging frame arrival time calculation module (116) is used to calculate the time it takes for the ranging frame to arrive at another terminal from the current terminal.

[0018] Preferably, the ranging frame receiving unit (200) further comprises a high-speed serial receiving interface (114); the high-speed serial receiving interface (114) is used to receive a ranging frame feedback signal in the form of a serial data stream sent by another terminal, and convert it into parallel data and send it to the data frame deframing module (115); the high-speed serial receiving interface (114) also outputs a receiving clock to the ADC sampling calculation module (117).

[0019] Preferably, the ADC sampling calculation module (117) performs beat sampling on the receiving clock based on the sending clock; obtains the frequency difference and phase difference between the sending clock and the receiving clock through frequency and phase discrimination, which is where f r is the frequency of the receiving clock, f s is the frequency of the sending clock, f Δ is the frequency difference between the sending clock and the receiving frequency, is the phase difference between the sending clock and the receiving clock.

[0020] Further preferably, the ranging frame sending time calculation module (118) obtains the ranging frame sending time calculation value by setting The calculated value of the ranging frame sending time is T s_precision ; T s The ranging frame sending time calculated by another terminal is obtained from the ranging frame feedback signal.

[0021] More preferably, the ranging calculation module (119) obtains the ranging calculation value according to the ranging frame arrival time and the ranging frame transmission time calculated by another terminal in the ranging frame feedback signal, using the formula T d1 =T r1 -T s_precision1 With T d2 =T r2 -T s_precision2 , calculate the pseudo-range value respectively; where T d1 is the pseudo-ranging value of the current terminal, T d2 is the pseudo-ranging value of the other terminal; T r1 The time when the ranging frame calculated for the current terminal arrives at the other terminal; T r2 The time calculated by another terminal for the ranging frame sent by it to arrive at the current terminal; T s_precision1 T is the calculated value of the ranging frame sending time obtained by the current terminal; s_precision2 is the calculated value of the ranging frame sending time obtained by the other terminal; and then according to the formula T dist =(T d1 +T d2 ) / 2, and obtain the distance calculation value T dist , multiply the distance calculated by the speed of light to get the distance between the two terminals.

[0022] On the other hand, the present invention provides a high-precision distance measurement method based on beat sampling, comprising the following steps:

[0023] S1: configuring the above two completely identical terminals, each terminal comprising a ranging frame sending unit (100), a ranging frame receiving unit (200), an ADC sampling calculation module (117), a ranging frame sending time calculation module (118) and a ranging calculation module (119);

[0024] S2: The ranging frame sending unit (100) of the current terminal sends a ranging frame to another terminal; the ranging frame includes the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module (111), and the pseudo-range value calculated by the current terminal. When the other terminal receives the ranging frame, it returns a ranging frame feedback signal including the ranging frame sending time and the ranging frame arrival time, and the ranging frame feedback signal is received by the ranging frame receiving unit (200) of the current terminal; similarly, the ranging frame sending unit (100) of the other terminal also sends a ranging frame to the current terminal, and receives the ranging frame feedback signal returned by the current terminal;

[0025] S3: Both terminals to be measured use an ADC sampling and calculation module (117) to complete the beat sampling of the current terminal's sending clock to the receiving clock, that is, respectively obtain the sending clock output by the ranging frame sending unit (100) and the receiving clock output by the ranging frame receiving unit (200), obtain the frequency difference and phase difference between the sending clock and the receiving clock, and calculate the receiving clock frequency;

[0026] S4: the ranging frame transmission time calculation module (118) of each current terminal obtains the ranging frame transmission time calculated by another terminal from the ranging frame feedback signal sent by another terminal, and the transmission clock frequency, the reception clock frequency, and the frequency difference and the phase difference obtained from the ADC sampling calculation module (117), and obtains the ranging frame transmission time calculation value of each terminal;

[0027] S5: the ranging calculation module (119) of each terminal calculates its own pseudo-range value according to the ranging frame arrival time calculated by another terminal in the ranging frame feedback signal and the ranging frame sending time calculated value of the current terminal, and calculates the ranging calculation value according to the respective pseudo-range values;

[0028] S6: further eliminate the inherent delay part that affects the distance measurement calculation value, obtain a corrected distance measurement calculation value, and multiply the distance measurement calculation value by the speed of light to obtain the distance between the two terminals.

[0029] Preferably, the inherent delay part affecting the ranging calculation value is further eliminated in step S6 to obtain a corrected ranging calculation value, which is to set the transmission inherent delay of the ranging frame to Tdelay , then the distance D between the two terminals is D = (T dist -T delay )×c,T dist is the distance calculation value, and c is the speed of light.

[0030] The high-precision distance measurement system and method based on beat sampling provided by the present invention have the following beneficial effects compared with the prior art:

[0031] (1) This solution uses an ADC chip to obtain the frequency difference and phase difference between the local transmit clock and the receive clock, which not only improves the ranging accuracy, but also reduces the system's requirements for the clock source and reduces the complexity of the system;

[0032] (2) This solution can eliminate the influence of the Doppler effect when restoring the receiving clock frequency, making the final calculated ranging value more accurate and reliable;

[0033] (3) Further eliminating the inherent delay part can further improve the ranging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A structural block diagram of each terminal of a high-precision ranging system based on beat sampling according to the present invention;

[0036] Figure 2 A flowchart of a high-precision distance measurement system and method based on beat sampling according to the present invention;

[0037] Figure 3 A flow chart of frequency and phase discrimination for beat sampling by an ADC sampling calculation module of a high-precision distance measurement system and method based on beat sampling according to the present invention;

[0038] Figure 4 A waveform diagram of digital mixing for beat sampling by an ADC sampling calculation module of a high-precision distance measurement system and method based on beat sampling according to the present invention;

[0039] Figure 5 It is a schematic diagram of an output waveform of an ADC sampling calculation module of a high-precision distance measurement system and method based on beat sampling in the present invention for making a zero-crossing judgment on a difference frequency signal;

[0040] Figure 6The present invention provides a line graph of relative errors of frequency and phase discrimination in beat sampling performed by an ADC sampling calculation module of a high-precision distance measurement system and method based on beat sampling. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The technical solution of the present invention is achieved as follows: Figure 1 As shown, on the one hand, the present invention provides a high-precision ranging system based on beat sampling, including two completely identical terminals; wherein the two terminals both include a ranging frame sending unit 100, a ranging frame receiving unit 200, an ADC sampling calculation module 117, a ranging frame sending time calculation module 118, and a ranging calculation module 119. There is interaction between the two terminals, and the processing content of the ranging frame currently sent to the other terminal by each terminal, as well as the format of the ranging frame feedback signal generated by any terminal after receiving the ranging frame are also consistent. Figure 1 The structure shown is a block diagram of the structure of any terminal.

[0043] The ranging frame sending unit 100 is used to generate a ranging frame and send it to another terminal; the ranging frame sending unit 100 also outputs a sending clock; the ranging frame may include information such as a start segment, the ranging frame sending time of the current terminal, and an end segment. Figure 1 It can be seen that the ranging frame is sent to another terminal in the form of a serial data stream. In serial communication, binary data appears in the form of digital signals. Whether sending or receiving, a clock signal must be used to locate the transmitted data.

[0044] like Figure 1 As shown, the ranging frame sending unit 100 further includes a local ranging frame sending time calculation module 111, a data frame framing module 112 and a high-speed serial sending interface 113; wherein,

[0045] A local ranging frame sending time calculation module 111 is used to calculate the sending time of the current ranging frame of the current terminal;

[0046] The data frame framing module 112 is used to integrate the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module 111, and the pseudo-range value calculated by the current terminal according to the format of the data frame to obtain a ranging frame; in addition, the data frame framing module 112 also sends a ranging frame sending flag FLAG_S to the local ranging frame sending time calculation module 111. When the local ranging frame sending time calculation module 111 receives the ranging frame sending flag FLAG_S, it calculates the sending time of the current ranging frame of the current terminal within the valid lifetime of the ranging frame sending flag FLAG_S and sends it to the data frame framing module 112; the data frame framing module 112 encapsulates to obtain a ranging frame sent by the current terminal to another terminal.

[0047] The data frame assembly module 112 outputs the ranging frame in the form of parallel data. After receiving the ranging frame, the high-speed serial transmission interface 113 converts the ranging frame into a serial data stream and outputs it to another terminal, and outputs a transmission clock to the ADC sampling calculation module 117 at the transmission time.

[0048] The ranging frame receiving unit 200 is used to receive a ranging frame feedback signal including the ranging frame sending time calculated by another terminal, and obtain the time when the ranging frame calculated by the current terminal arrives at the other terminal; the ranging frame receiving unit 200 also outputs a receiving clock.

[0049] Specifically, Figure 1 As shown, the ranging frame receiving unit 200 includes a high-speed serial receiving interface 114, a data frame de-framing module 115 and a ranging frame arrival time calculation module 116; wherein,

[0050] The high-speed serial receiving interface 114 is used to receive the ranging frame feedback signal in the form of a serial data stream sent by another terminal, and convert it into parallel data and send it to the data frame deframing module 115; the high-speed serial receiving interface 114 also outputs a receiving clock to the ADC sampling calculation module 117.

[0051] The data frame deframing module 115 is used to receive the ranging frame feedback signal input by another terminal for deframing and splitting. The ranging frame feedback signal can also be encapsulated in the form of a data frame, so the ranging frame sending time calculated by the other terminal and the pseudorange value calculated by the other terminal can be extracted from the ranging frame feedback signal.

[0052] The ranging frame arrival time calculation module 116 is used to calculate the time it takes for a ranging frame to arrive at another terminal from a current terminal, ie, the ranging frame arrival time.

[0053] like Figure 1As shown, the ADC sampling calculation module 117 is used to obtain the sending clock output by the ranging frame sending unit 100 and the receiving clock output by the ranging frame receiving unit 200, and to perform beat sampling on the receiving clock based on the sending clock; the frequency difference and phase difference between the sending clock and the receiving clock are obtained by frequency and phase discrimination; since the sending clock is known, the frequency difference and phase difference between the two frequencies can be known by obtaining the frequency of the receiving clock.

[0054] Specifically, it is where f r is the frequency of the receiving clock, f s is the frequency of the sending clock, f Δ is the frequency difference between the sending clock and the receiving frequency, is the phase difference between the sending clock and the receiving clock. Because the frequency of the sending clock of the current terminal is known, the frequency difference and phase difference between the two frequencies can be measured by the ADC sampling calculation module 117, and the frequency of the receiving clock can be calculated by the above formula. The frequency difference and phase difference are obtained by sampling through a high-speed ADC chip, which is to compare the zero-crossing time and quantity of each sampling signal of the sending clock and the interpretation clock, and to judge the leading or lagging relationship of the two sampling signals. The ADC sampling calculation module 117 is mainly implemented by an ADC chip, and the ADC chip can be selected to support dual-channel sampling. Data sampling technology is divided into real-time sampling and equivalent sampling. The signal capture capability of real-time sampling is limited by the maximum sampling rate of ADC. Real-time sampling is the process of completing the entire sampling after one trigger, and usually meets the Nyquist sampling theorem, and the sampling frequency is at least twice the highest frequency of the signal. In order to solve the data acquisition of high-frequency broadband periodic signals, an equivalent sampling method is adopted. Beat sampling is an equivalent sampling method, and its ADC sampling frequency can even be lower than the frequency of the measured signal, as long as the beat of each sampling meets the Nyquist theorem.

[0055] like Figure 1 As shown, the ranging frame transmission time calculation module 118 is used to obtain the ranging frame transmission time calculated by another terminal from the ranging frame feedback signal, and the transmission clock frequency and the receiving clock frequency obtained from the ADC sampling calculation module 117, and obtain the ranging frame transmission time calculation value. The ranging frame transmission time calculation value here has higher accuracy than the ranging frame arrival time obtained by the ranging frame arrival time calculation module 116.

[0056] The ranging frame transmission time calculation module 118 obtains the ranging frame transmission time calculation value, which is The calculated value of the ranging frame sending time is T s_precision ; T sThe receiving clock frequency f is the ranging frame sending time calculated by the other terminal from the ranging frame feedback signal. r The frequency f of the sending clock is obtained by the aforementioned ADC sampling calculation module 117. s is known, so the calculated value of the ranging frame sending time T can be obtained s_precision Then the ranging frame sends the calculated time value T s_precision It is further sent to the distance measurement calculation module 119.

[0057] The ranging calculation module 119 obtains the ranging calculation value according to the ranging frame arrival time and the ranging frame sending time calculated by the other terminal in the ranging frame feedback signal. The speed of light in different media is different, so the ranging result presented can be expressed in time; if it is to be converted into distance, the ranging calculation value is multiplied by the speed of light to obtain the distance between the two terminals.

[0058] Specifically, the formula T d1 =T r1 -T s_precision1 With T d2 =T r2 -T s_precision2 , calculate the pseudo-range value respectively; where T d1 is the pseudo-ranging value of the current terminal, T d2 is the pseudo-ranging value of the other terminal; T r1 The time when the ranging frame calculated for the current terminal arrives at the other terminal; T r2 The time calculated by another terminal for the ranging frame sent by it to arrive at the current terminal; T s_precision1 T is the calculated value of the ranging frame sending time obtained by the current terminal; s_precision2 is the calculated value of the ranging frame sending time obtained by the other terminal; and then according to the formula T dist =(T d1 +T d2 ) / 2, and obtain the distance calculation value T dist , multiply the distance calculated by the speed of light to get the distance between the two terminals.

[0059] Distance calculation value T dist In the calculation value T, the transmission and processing delay inherent in the terminal is inevitably included. In actual use, it is necessary to deduct this part of the transmission and processing delay inherent in the terminal and calculate the distance measurement value T. dist After correction, multiplying by the speed of light, the exact distance D between the two terminals can be obtained.

[0060] In addition, the present invention also provides a high-precision distance measurement method based on beat sampling, comprising the following steps:

[0061] S1: configure the two identical terminals mentioned above, each terminal includes a ranging frame sending unit 100, a ranging frame receiving unit 200, an ADC sampling calculation module 117, a ranging frame sending time calculation module 118 and a ranging calculation module 119;

[0062] S2: The ranging frame sending unit 100 of the current terminal sends a ranging frame to another terminal; the ranging frame includes the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module 111, and the pseudorange value calculated by the current terminal. When the other terminal receives the ranging frame, it returns a ranging frame feedback signal including the ranging frame sending time and the ranging frame arrival time, and the ranging frame feedback signal is received by the ranging frame receiving unit 200 of the current terminal; similarly, the ranging frame sending unit 100 of the other terminal also sends a ranging frame to the current terminal, and receives the ranging frame feedback signal returned by the current terminal;

[0063] S3: Both terminals to be measured use the ADC sampling and calculation module 117 to complete the beat sampling of the current terminal's sending clock to the receiving clock, that is, respectively obtain the sending clock output by the ranging frame sending unit 100 and the receiving clock output by the ranging frame receiving unit 200, obtain the frequency difference and phase difference between the sending clock and the receiving clock, and calculate the receiving clock frequency;

[0064] S4: the ranging frame transmission time calculation module 118 of each current terminal obtains the ranging frame transmission time calculated by another terminal from the ranging frame feedback signal sent by another terminal, and the transmission clock frequency, the receiving clock frequency, and the frequency difference and the phase difference obtained from the ADC sampling calculation module 117, and obtains the ranging frame transmission time calculation value of each terminal;

[0065] S5: the ranging calculation module 119 of each terminal calculates its own pseudo-range value according to the ranging frame arrival time calculated by another terminal in the ranging frame feedback signal and the ranging frame sending time calculated value of the current terminal, and calculates the ranging calculation value according to the respective pseudo-range values;

[0066] S6: Further eliminate the inherent delay that affects the ranging calculation value, and set the transmission inherent delay of the ranging frame to T delay , then the distance D between the two terminals is D = (T dist -T delay )×c,T dist is the distance calculation value, c is the speed of light; the corrected distance calculation value is obtained through calculation, and the distance between the two terminals is obtained by multiplying the corrected distance calculation value by the speed of light.

[0067] In actual use, due to the individual differences in clock sources on different terminals that can communicate with each other, and the Doppler frequency shift caused by the relative movement between the terminals, there is a frequency difference between the receiving clock restored by the ranging frame receiving unit 200 and the local sending clock, which will introduce a ranging error. This solution uses a beat sampling method, using frequency and phase discrimination to obtain the frequency difference and phase difference between the sending clock and the receiving clock, so as to correct the ranging value.

[0068] In order to verify the effect of this solution, this solution simulates the beat sampling process. Figure 3 As shown, the simulation produces a frequency deviation of 10 -4 , the frequency value is (1±10 -4 )×156.25MHz receiving clock signal; using the local sending clock as the reference clock, generating a four-times 625MHz clock signal as the sampling clock of the ADC sampling calculation module, using the ADC chip to sample the receiving clock, thereby obtaining the sampled receiving clock signal; using the reference clock to generate two orthogonal 156.25MHz local digital carriers, digitally mixing the two orthogonal local digital carriers with the sampled receiving clock signal, and obtaining the following Figure 4 The two mixed signals shown in the figure are filtered by low-pass filters, i.e. LRF filters, to obtain difference frequency signals. The positive and negative signs of the frequency deviation can be obtained by judging the phase relationship of the difference frequency signals of the two orthogonal branches. The difference frequency signal is judged to be zero-crossing, such as Figure 5 As shown, a zero-crossing pulse sequence is obtained. Each zero-crossing pulse represents the starting position of each difference frequency signal cycle. The time value of each zero-crossing pulse is subtracted from the time value of the previous zero-crossing pulse to obtain the cycle of each difference frequency signal. By counting the number of difference frequency signal cycles within a certain period of time, the integer part of the number of cycles can be used to calculate the frequency difference, and the decimal part can be used to calculate the phase difference. After obtaining the frequency difference and phase difference between the sending clock and the receiving clock, the formula Calculate the accurate receiving clock frequency. The above content is the process and method of frequency and phase discrimination.

[0069] The above simulation process obtains the frequency difference and phase difference, and calculates the period measurement error of the difference frequency signal, thereby obtaining the corresponding measurement error of the receiving clock frequency. This measurement error is the ranging error caused by ranging, which is given by Figure 6 It can be seen that the error is kept at 10 -3 The distance measurement accuracy can be guaranteed within an order of magnitude.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-precision distance measurement system based on beat sampling, characterized in that: Comprising two identical terminals; wherein the two terminals both include A ranging frame sending unit (100) is used to generate a ranging frame and send it to another terminal; the ranging frame sending unit (100) also outputs a sending clock; A ranging frame receiving unit (200) is used to receive a ranging frame feedback signal including a ranging frame transmission time calculated by another terminal, and obtain the time when the ranging frame calculated by the current terminal arrives at the other terminal; the ranging frame receiving unit (200) also outputs a receiving clock; The ADC sampling calculation module (117) is used to obtain a sending clock output by a ranging frame sending unit (100) and a receiving clock output by a ranging frame receiving unit (200), and to perform beat sampling on the receiving clock based on the sending clock; and to obtain a frequency difference and a phase difference between the sending clock and the receiving clock by frequency and phase discrimination; A ranging frame sending time calculation module (118) is used to obtain the ranging frame sending time calculated by another terminal from the ranging frame feedback signal, and the sending clock frequency, receiving clock frequency, and frequency difference and phase difference obtained from the ADC sampling calculation module (117), to obtain a calculated value of the ranging frame sending time; A ranging calculation module (119) is configured to obtain a ranging calculation value according to a ranging frame arrival time and a ranging frame transmission time calculated by another terminal in a ranging frame feedback signal; The ranging frame sending unit (100) comprises A local ranging frame sending time calculation module (111), used to calculate the sending time of the current ranging frame of the current terminal; A data frame assembly module (112) is used to integrate the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module (111) and the pseudo-range value calculated by the current terminal according to the format of the data frame to obtain a ranging frame; The ADC sampling calculation module (117) performs beat sampling on the receiving clock based on the sending clock; obtains the frequency difference and phase difference between the sending clock and the receiving clock through frequency and phase discrimination, which is where f r is the frequency of the receiving clock, f s is the frequency of the sending clock, f Δ is the frequency difference between the sending clock and the receiving frequency, is the phase difference between the sending clock and the receiving clock; The receiving clock is sampled using an ADC sampling calculation module (117) to obtain a sampled receiving clock signal; two orthogonal local digital carriers are generated using a reference clock, and the two orthogonal local digital carriers are digitally mixed with the sampled receiving clock signal to obtain two mixed signals; the mixed signals are filtered using low-pass filters to obtain a difference frequency signal; the positive and negative signs of the frequency deviation are obtained by determining the phase relationship of the difference frequency signals of the two orthogonal branches; the difference frequency signal is judged to be zero-crossing to obtain a zero-crossing pulse sequence, each zero-crossing pulse represents the starting position of each difference frequency signal cycle, the time value of each zero-crossing pulse is subtracted from the time value of the previous zero-crossing pulse to obtain the cycle of each difference frequency signal, and the integer part of the number of cycles can be used to calculate the frequency difference, and the decimal part can be used to calculate the phase difference; The ranging frame sending time calculation module (118) obtains the ranging frame sending time calculation value, which is The calculated value of the ranging frame sending time is T s_precision ; T s The ranging frame sending time calculated by another terminal is obtained from the ranging frame feedback signal.

2. A high-precision distance measurement system based on beat sampling according to claim 1, characterized in that: The ranging frame sending unit (100) further comprises a high-speed serial sending interface (113); the high-speed serial sending interface (113) is used to convert the ranging frame integrated by the data frame framing module (112) into a serial data stream for output to another terminal, and to output a sending clock to the ADC sampling calculation module (117).

3. A high-precision distance measurement system based on beat sampling according to claim 2, characterized in that: The ranging frame receiving unit (200) comprises A data frame de-framing module (115) is used to receive input from another terminal, perform de-framing and split the frame, and obtain the ranging frame sending time calculated by the other terminal and the pseudo-range value calculated by the other terminal; The ranging frame arrival time calculation module (116) is used to calculate the time it takes for the ranging frame to arrive at another terminal from the current terminal.

4. A high-precision distance measurement system based on beat sampling according to claim 3, characterized in that: The ranging frame receiving unit (200) further comprises a high-speed serial receiving interface (114); the high-speed serial receiving interface (114) is used to receive a ranging frame feedback signal in the form of a serial data stream sent by another terminal, and convert it into parallel data and send it to a data frame de-framing module (115); the high-speed serial receiving interface (114) also outputs a receiving clock to an ADC sampling calculation module (117).

5. The high-precision distance measurement system based on beat sampling according to claim 1, characterized in that: The ranging calculation module (119) obtains the ranging calculation value according to the ranging frame arrival time calculated by another terminal and the ranging frame transmission time calculated in the ranging frame feedback signal, using the formula T d1 =T r1 -T s_precision1 With T d2 =T r2 -T s_precision2 , calculate the pseudo-range value respectively; where T d1 is the pseudo-ranging value of the current terminal, T d2 is the pseudo-ranging value of the other terminal; T r1 The time when the ranging frame calculated for the current terminal arrives at the other terminal; T r2 The time calculated by another terminal for the ranging frame sent by it to arrive at the current terminal; T s_precision1 T is the calculated value of the ranging frame sending time obtained by the current terminal; s_precision2 is the calculated value of the ranging frame sending time obtained by the other terminal; and then according to the formula T dist =(T d1 +T d2 ) / 2, and obtain the distance calculation value T dist , multiply the distance calculated by the speed of light to get the distance between the two terminals.

6. A high-precision distance measurement method based on beat sampling, characterized in that: The steps include: S1: configuring a high-precision ranging system based on beat sampling as claimed in any one of claims 2 to 5, configuring two completely identical terminals, each terminal comprising a ranging frame sending unit (100), a ranging frame receiving unit (200), an ADC sampling calculation module (117), a ranging frame sending time calculation module (118) and a ranging calculation module (119); S2: The ranging frame sending unit (100) of the current terminal sends a ranging frame to another terminal; the ranging frame includes the data required to be sent by the current terminal, the current ranging frame sending time obtained from the local ranging frame sending time calculation module (111), and the pseudo-range value calculated by the current terminal. When the other terminal receives the ranging frame, it returns a ranging frame feedback signal including the ranging frame sending time and the ranging frame arrival time, and the ranging frame feedback signal is received by the ranging frame receiving unit (200) of the current terminal; similarly, the ranging frame sending unit (100) of the other terminal also sends a ranging frame to the current terminal, and receives the ranging frame feedback signal returned by the current terminal; S3: Both terminals to be measured use an ADC sampling and calculation module (117) to complete the beat sampling of the current terminal's sending clock to the receiving clock, that is, respectively obtain the sending clock output by the ranging frame sending unit (100) and the receiving clock output by the ranging frame receiving unit (200), obtain the frequency difference and phase difference between the sending clock and the receiving clock, and calculate the receiving clock frequency; S4: the ranging frame transmission time calculation module (118) of each current terminal obtains the ranging frame transmission time calculated by another terminal from the ranging frame feedback signal sent by another terminal, and the transmission clock frequency, the reception clock frequency, and the frequency difference and the phase difference obtained from the ADC sampling calculation module (117), and obtains the ranging frame transmission time calculation value of each terminal; S5: the ranging calculation module (119) of each terminal calculates its own pseudo-range value according to the ranging frame arrival time calculated by another terminal in the ranging frame feedback signal and the ranging frame sending time calculated value of the current terminal, and calculates the ranging calculation value according to the respective pseudo-range values; S6: further eliminate the inherent delay part that affects the distance measurement calculation value, obtain a corrected distance measurement calculation value, and multiply the distance measurement calculation value by the speed of light to obtain the distance between the two terminals.

7. The high-precision distance measurement method based on beat sampling according to claim 6, characterized in that: Step S6 further eliminates the inherent delay part that affects the distance measurement calculation value to obtain the corrected distance measurement calculation value, which is to set the transmission inherent delay of the ranging frame to T delay , then the distance D between the two terminals is D = (T dist -T delay )×c,T dist is the distance calculation value, and c is the speed of light.

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