Method and system for improving precision of laser ranging system and storage medium

Abstract

The invention discloses a method and system for improving the precision of a laser ranging system, and a storage medium. The method comprises the following steps: S1, obtaining an echo signal of the laser ranging system through a superconducting nanowire single-photon detector; s2, inputting a dominant wave signal, an echo signal, 1PPS and GPS information emitted by the laser ranging system into different channels of a time-to-digital converter to obtain related time information of the laser ranging system; s3, calculating the real time of the effective event according to the data in the time-to-digital converter; s4, de-noising processing is carried out by setting a channel time window and a coincidence time window; s5, according to the denoised data and the forecast file, performing cross-cycle calculation to obtain the measurement distance of the target; according to the method, the high-speed SNSPD can be applied to the laser ranging system to obtain accurate measurement time, a large amount of data can be processed in time, the precision of the laser ranging system is improved, and long-distance ranging can be achieved.

Description

Technical Field

[0001] The present invention relates to a laser ranging system, in particular to a method, a system and a storage medium for improving the accuracy of a laser ranging system. Background Art

[0002] As one of the important components in a laser ranging system, the performance of a detector will directly affect the detection ability of the system. The superconducting nanowire single-photon detector (SNSPD) is a single-photon detector with excellent performance, having characteristics such as high detection efficiency, low dark count, short dead time, etc., and being able to perform multiple photon detections within a distance gate detection range, which can effectively improve the detection probability and the detection signal-to-noise ratio, thereby enhancing the detection ability of the system.

[0003] The working mechanism of SNSPD is the phase transition of the superconducting state of the superconducting nanowire triggered by a single photon to a resistive state. Its theoretical speed limit is determined by the thermal relaxation time and can reach up to dozens of GHz at most. However, its nanowire structure determines that SNSPD has a large dynamic inductance. Therefore, in practical applications, the speed of SNSPD is generally determined by its dynamic inductance. A typical SNSPD has a meandering line structure, and the photon response speed is about 10 Mcps (counts per second).

[0004] With the rapid development of applications such as long-distance laser ranging, higher requirements are gradually put forward for the performance of SNSPD. One of the key technical indicators is a higher photon response speed. Recently, with the further research on high-speed SNSPD, a multi-mode fiber-coupled superconducting nanowire single-photon detector has emerged, which improves the counting rate of the detector while expanding the photosensitive surface of the detector. Using a 16-wire fully wound nanowire array, the overall detector has achieved a system detection efficiency (SDE) of more than 50% and a maximum counting rate of 3.1 Gcps, as well as a counting rate of 1.3 Gcps when the efficiency drops by half. However, as the detection rate of SNSPD gradually increases, the difficulty of its data acquisition also becomes greater and greater.

[0005] When applying the multi-mode fiber-coupled superconducting nanowire single-photon detector to fields such as lidar, there are still the following difficulties in signal acquisition: high-precision time measurement, the error of internal time synchronization of the data acquisition system and synchronization with the reference time will affect the data processing result; the data volume is large, and the data volume of several hundred MHz per second causes difficulties for real-time processing. Therefore, general data acquisition systems cannot meet the requirements of high-speed SNSPD. Summary of the Invention

[0006] Objective of the Invention: The objective of the present invention is to provide a method, a system, and a storage medium for improving the accuracy of a laser ranging system, which can apply a high-speed SNSPD to the laser ranging system, accurately obtain the measurement time, efficiently and timely process a large amount of data, and achieve long-distance ranging.

[0007] Technical Solution: The method for improving the accuracy of a laser ranging system according to the present invention includes the following steps:

[0008] S1. Detect the echo photons of the laser ranging system through a superconducting nanowire single-photon detector and convert them into multiple echo signals;

[0009] S2. Input the main wave signal, echo signal, 1PPS signal, and GPS information emitted by the laser ranging system into different channels of a time-to-digital converter to obtain the relevant time information of the laser ranging system. There are multiple channels in the time-to-digital converter that match the echo signals;

[0010] S3. Convert the information obtained by the time-to-digital converter into binary and separate the data to obtain control identification information, channel information, and time information. Calculate the true time of each valid event according to the separated information, and calculate its absolute time according to the true time of each valid event;

[0011] S4. Set the channel time window according to the satellite orbit prediction data, and only retain the signals within the channel time window in each echo signal channel; calculate the time difference between the signals within all channel time windows and the corresponding main wave signal as the round-trip light travel time. Arrange the time differences calculated in each echo signal channel in order, and judge whether there are time differences within the preset coincidence time window in other echo signal channels based on the time difference in any echo signal channel. If there are, retain the time difference, otherwise eliminate it;

[0012] S5. According to the time differences and prediction files screened in step S4, simultaneously perform data filtering processing and cross-cycle calculation in a multi-threaded parallel and shared memory manner to obtain the measured distance of the target.

[0013] Based on the above technical solution, since the superconducting nanowire single-photon detector, i.e., SNSPD, itself has the characteristics of high detection efficiency and resolution, using it to obtain the echo signal can itself improve the accuracy of the laser ranging system. And a time-to-digital converter is used to obtain the relevant time information of the laser ranging system; by separating and processing the data in the time-to-digital converter and combining the 1PPS and GPS information to calculate the absolute time corresponding to the main wave signal and the echo signal relative to the standard time, the error existing in the conversion from the internal time of the time-to-digital converter to the standard time in the prior art is reduced, and the target ranging calculated according to the absolute time is also more in line with the actual situation, so the measurement accuracy of the laser ranging system can also be improved; by setting multiple channels in the time-to-digital converter that match the echo signal, and then setting a channel time window to preliminarily screen the data in each echo signal channel, a large amount of noise data outside the channel time window can be removed. Then calculate the time difference between the signals in all channel time windows of different echo signal channels and the corresponding main wave signal, and then select any one echo signal channel as the basis, and screen through a preset coincidence time window to retain the time differences that meet the requirements. Through these two steps of denoising processing, a large amount of noise data can be removed, greatly reducing the processing volume in the subsequent data processing process, improving the processing efficiency, enabling the large amount of data collected by the high-speed SNSPD to be processed in a timely and effective manner, and at the same time removing a large amount of noise data, which can also improve the accuracy of the final measurement result; when calculating the target measurement distance, judge the corresponding relationship between the echo signal and the transmitted signal according to the prediction data, so as to complete the cross-cycle calculation and achieve long-distance ranging. Therefore, this method can overcome the problems of insufficient time accuracy and large amount of data existing in the application of SNSPD in the laser ranging system, enable SNSPD to effectively play its role of high detection efficiency and resolution, improve the accuracy of the laser ranging system, and at the same time can achieve long-distance ranging.

[0014] The system for improving the accuracy of a laser ranging system according to the present invention, the system includes:

[0015] A signal acquisition module: used to detect echo photons of the laser ranging system through a superconducting nanowire single-photon detector and convert them into a plurality of echo signals;

[0016] A time acquisition module: used to input the main wave signal, echo signal, 1PPS and GPS information emitted by the laser ranging system into different channels of a time-to-digital converter to obtain the relevant time information of the laser ranging system, and a plurality of channels matching the echo signal are provided in the time-to-digital converter;

[0017] De-noising module: used to remove noise data from the echo signal in the time-to-digital converter. The specific process is to first confirm the channel time window according to the satellite orbit prediction data, and remove the data outside the channel time window in each echo signal channel; then calculate the time difference between the corresponding data in different echo signal channels in chronological order, and retain the data whose time difference in any two echo signal channels is not greater than the set value;

[0018] Data parsing module: used to convert the information obtained by the time digital converter into binary and separate the data to obtain control identification information, channel information and time information, calculate the real time of each valid event according to the separated information, and calculate the absolute time of each valid event according to the real time of each valid event;

[0019] Distance measurement module: It is used to perform data filtering and cross-cycle calculation to obtain the measured distance of the target based on the time difference and forecast file filtered out by the denoising module, using multi-threaded parallelism and shared memory.

[0020] The computer-readable storage medium storing one or more programs described in the present invention includes one or more programs including instructions, and when the instructions are executed by a computing device, the computing device executes any one of the above methods.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: acquiring echo signals through superconducting nanowire single-photon detectors can improve the accuracy of signal acquisition, separating and extracting the time digital converter data to calculate the absolute time for subsequent ranging calculations, reducing the error of converting the internal time of the time digital converter to the standard time, and improving the measurement accuracy; then, a large amount of noise data can be removed through denoising processing, reducing the subsequent data processing volume and improving the measurement accuracy; and combining with forecast data for cross-period calculations can realize long-distance ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the laser ranging system of the present invention;

[0024] Figure 3 A schematic diagram of signal acquisition of the present invention;

[0025] Figure 4 is a timing diagram of the laser ranging system of the present invention;

[0026] Figure 5 It is a dot plot of the time without denoising and the time of two-way light travel;

[0027] Figure 6It is a dot plot of the time after denoising processing and the round-trip light travel time. Specific Embodiment

[0028] As shown in the figure, the method for improving the accuracy of a laser ranging system according to the present invention includes the following steps:

[0029] S1. Detect the echo photons of the laser ranging system through a superconducting nanowire single-photon detector and convert them into echo signals;

[0030] The laser ranging system uses a 700mm telescope as the ground laser transmitter and echo receiver. The laser ranging telescope loads system parameters according to the satellite orbit prediction data file, searches for and tracks the measurement target; at the same time, a high-speed camera is used to realize the real-time monitoring and correction of the laser pointing; the laser emits laser, the emission wavelength of the laser is 1064nm, the emission frequency is 30Hz, and at the laser exit, a Beam Splitter is used to separate a part of the signal and restore it to an electrical pulse as the main wave signal. The optical pulse is reflected at the measurement target, and the time difference between the echo signal and the main wave signal corresponds to the distance of the measurement target. The high-speed superconducting nanowire single-photon detector responds to the echo photons and converts the optical signal into an electrical signal; while having a high detection rate, the superconducting nanowire single-photon detector has a large photosensitive area, can be coupled with a large-aperture optical system, and improves the system detection efficiency; the superconducting nanowire single-photon detector mentioned in this article refers to a high-speed superconducting nanowire single-photon detector with a maximum counting rate of 3.1 Gcps and multiple channels.

[0031] In this embodiment, the multimode fiber-coupled high-speed superconducting nanowire single-photon detector operates in the 1064nm near-infrared band. The 1064nm wavelength has a high atmospheric transmittance and a small sky background radiation. Using a laser of this wavelength for satellite ranging helps to improve the detection ability of the ranging system.

[0032] S2. Input the main wave signal, echo signal, 1PPS, and GPS information emitted by the laser ranging system into different channels of the time-to-digital converter to obtain the relevant time information of the laser ranging system. There are multiple channels in the time-to-digital converter that match the echo signal;

[0033] The time-to-digital converter, that is, the TDC, includes: a reference clock input (REF IN), a counting signal input (CH1-CH16), a GPS interface, a USB3.0 interface, and an SFP optical module interface;

[0034] The input signal level standard of the reference clock is defaulted to LVTTL. The reference clock input is an externally provided clock signal. In a high-speed data acquisition system, the reference clock ensures the accuracy of the sampling time. The input frequency is 10 MHz. Specifically, first turn off the TDC and then connect the 10 MHz signal (the duty cycle of the connected signal should be set to 50% - 60%). The counting signal input is an analog input interface, and the input is the signal to be collected. Specifically: the main wave signal is connected to channel CH6, the echo signal is connected to channels CH1 - CH4, and 1PPS is connected to channel CH5; the GPS interface embeds GPS information into the time tag data, and the time of the data acquisition computer can be synchronized to the TDC using NTP for long-distance multi-terminal synchronization; the USB3.0 interface and the SFP optical module interface are both data transmission interfaces. USB3.0 supports a maximum event transmission rate of 40 M / s, and SFP supports a maximum time transmission rate of 280 M / s. When both are connected simultaneously, the system will preferentially select the SFP interface.

[0035] The time-to-digital converter synchronizes the time of the data acquisition computer using NTP; performs CH signal threshold settings on the TDC, including three settings: "trigger", "impedance", and "threshold level". This part is mainly used to determine the time measurement points of the input signal; the trigger is set to the rising edge, the signal input impedance is set to 50 Ω, the threshold level of the main wave signal is set to 30 mV, and the threshold level of the echo signal is set to 50 mV. When the signal is at the rising edge and reaches the threshold level at the set impedance, the starting moment is used as the starting point for the time measurement of the signal.

[0036] The time-to-digital converter can achieve high-precision time synchronization measurement. After testing, the internal time synchronization of the TDC is correct, the time deviation between the counting signal input channels is < 700 ps, which basically does not affect the target measurement. The internal time of the TDC is synchronized correctly with the reference time, and the measurable synchronization error is better than 1 ns. It is estimated that the synchronization error can be better than 10 ns (the rest comes from hardware factors such as cables, and most of them are not easy to measure), meeting the requirement of a synchronization accuracy of 100 ns.

[0037] The time when the main wave signal is sent, the time when the echo signal arrives, and the reference time are obtained through the time-to-digital converter, and all event information with time stamps is transmitted to the data processing module through the interface (USB3.0 or 10 Gigabit Ethernet).

[0038] S3. Convert the information obtained by the time-to-digital converter into binary and separate the data to obtain control identification information, channel information, and time information. Calculate the real time of each valid event according to the separated information, and calculate its absolute time according to the real time of each valid event. Valid events refer to synchronous clock signals or photon counting signals. In this article, they refer to the main wave signal and the echo signal.

[0039] Parse the original file data saved by the time digital converter. First, convert the original hexadecimal data into binary format. Each valid data contains 32-bit information. Separate the data according to the protocol. The specific protocol is that the highest 1 bit is the control identification bit. "0" means that the lower 31 bits represent valid time information, and "1" means that the lower 31 bits represent some time information bit overflows. For example, if there is a time information bit overflow in an echo signal, then the first bit of the first data of the signal is "0", and the first bit of the second data is "1". If the two data can represent the echo signal completely when combined, then the first bit of the third data is "0", indicating that this is a new signal. If the two data still cannot represent the echo signal completely when combined, that is, there is still a time information bit overflow, then the first bit of the third data is still "1", and so on, until the echo signal can be completely expressed, and then the first bit of the next data will become "0" to indicate the start data of a new echo signal; the lowest 25 bits represent the time information bits, recording the position of the current event on the time axis, with the unit of 1 ps; the remaining 6 bits represent the channel information bits (CH1~CH16). If the channel information bits are "111111", it means that this data record is the overflow value, that is, ovfl_value, indicating the time information bit overflow indication. At this time, the lowest 10 bits are used to represent the overflow count value, that is, T' mentioned below. v 。

[0040] Separate to obtain the control identification bit array pDataFlag_Bit1, that is, the Flag array of String type, the channel information bit array pDataChan_Bit6, that is, the Channel array of byte type, and the time information bit array pDataTime_Bit25, that is, the Time array of long type. The above three arrays represent the data type of the event, the channel number where the response occurs, and the corresponding time tag respectively; then read the time information bit overflow count value to correct the event time information, that is, the real time, and calculate specifically according to the following formula

[0041] T real =[T″ v *N″ v +(T′ v +1)*N′ v +T v +1]*1ps

[0042] where, T real is the real time of the valid event, T″ v is the overflow times of the overflow count value, N″ v is the time value when the overflow count value itself has an overflow event, specifically 2 10 ×225 p.s., T' v is the overflow count value, N' v The time value for the overflow of valid event time information is 2 25 p.s.T v Time information of the valid event.

[0043] Based on the calculated real time, the absolute time is calculated by the following formula

[0044] T rjm =T real -t 1PPS +(HH×3600+mm×60+ss+SSS×10 -3 )×10 12

[0045] Among them, T rjm is the absolute time, T real is the real time, t 1PPS is the 1PPS time corresponding to the GPS time information, and HH, mm, ss, and SSS are the hour, minute, second, and millisecond values in the GPS time information, respectively.

[0046] S4, setting a channel time window according to the satellite orbit prediction data, and only retaining the signal in the channel time window in each echo signal channel; calculating the time difference between the signals in all channel time windows and the corresponding main wave signal as the two-way light travel, arranging the time difference calculated in each echo signal channel in order, and using the time difference in any echo signal channel as a reference to determine whether there is a time difference in the preset matching time window in other echo signal channels, if so, retaining the time difference, otherwise discarding it;

[0047] The specific steps include:

[0048] S4.1. Preliminary denoising: Set the channel time window according to the satellite orbit prediction data, and only retain the signal within the channel time window in each echo signal channel; because after each main wave signal is sent out, the return time of the echo signal can be calculated according to the prediction data of the satellite to be measured at that time, and a certain error tolerance range is added to the calculated time. For example, if the calculated return time is 67ns, then the channel time window can be set to 64-70ns, and the signals within this time period, that is, within this channel time window, are retained, and the rest are removed as noise data. Because there are multiple main wave signals, there are also multiple corresponding channel time windows. For example, in addition to 67-70ns, there may be 160-165ns, etc. Only the data within these channel time windows are retained, and the removal of the remaining large amounts of noise data can greatly reduce the subsequent data processing volume.

[0049] S4.2. Further denoising: Calculate the time difference between the signals within all channel time windows of each echo signal channel and the corresponding main wave signal (the corresponding main wave signal is determined according to satellite orbit prediction data), and arrange the calculated time differences in each echo signal channel in ascending order. Then, select any one echo signal channel as the reference, set a coincidence time window, and sequentially screen the time differences within this echo signal channel through the coincidence time window to retain the time difference data that meet the requirements, and the rest are removed as noise data. The specific screening process is as follows:

[0050] For example, taking the time difference calculated in the CH1 channel as the reference, the set coincidence time window is 2 ns. The coincidence time window is a time range, and the center of this range is any one time difference. For example, assuming the first time difference is 67 ns, then this time range is 66 - 68 ns. The screening depends on whether there are time differences in the CH2 - CH4 channels within the range of 66 - 68 ns. If there are corresponding time differences in all three channels of CH2 - CH4, it is considered that the first time difference of 67 ns in CH1 is valid and this data is retained; otherwise (that is, there is no corresponding data in any one of the CH2 - CH4 channels), the first time difference of 67 ns in CH1 is removed as noise data; each subsequent data is screened in this way until all time differences are screened. Since random noise photons are discrete in time and the times corresponding to them in different echo signal channels have no correlation and it is difficult to meet the above screening requirements, while the photons of the echo signal are time - correlated. Even if they are in different echo signal channels, especially the deviation value of the calculated time difference should be within a reasonable range. If it exceeds this range, it is considered that there is no correlation and it should be removed as noise.

[0051] Both the channel time window and the coincidence time window can be selected according to experience.

[0052] Through Figure 5 and Figure 6 ( Figure 6 The red line in is the satellite orbit prediction data), it can be seen that through the denoising process of the above two steps, a large amount of noise data can be effectively removed, which not only improves the accuracy of the final measurement result but also greatly improves the data processing efficiency, thus being able to effectively handle the large amount of data of high - speed SNSPD.

[0053] S5. According to the time differences and prediction files screened in step S4, adopt the method of multi - thread parallelism and shared memory to simultaneously perform data filtering processing and cross - cycle calculation to obtain the measured distance of the target.

[0054] It can be executed concurrently by three threads:

[0055] Thread 1: Responsible for performing cross-cycle calculations on the parsed main wave signal and echo signal, and can range to distant targets such as medium and high Earth orbit and geosynchronous orbit satellites.

[0056] Specifically, it is determined whether it is an Event event type according to the Flag array in the data (indicating that the data is the data collected by the counting signal input ch1-ch16), the main wave signal, echo signal, and 1PPS signal are determined according to the Channel array, and the measured orbital distance of the satellite is calculated according to the time values of the main wave signal and echo signal in the Time array; due to the large difference in distances of different targets during measurement or the large change in the distance of the same target, cross-cycle calculations are performed according to the orbital height predicted by the satellite or space debris in the prediction file, and ranging can be performed on distant targets such as medium and high Earth orbit and geosynchronous orbit satellites.

[0057] Satellite laser ranging (SLR) mainly ranges by the time-of-flight method. By measuring the round-trip time interval of the laser pulse between the ground observation station and the satellite, and combining the speed of light, the distance from the ground observation station to the satellite is calculated.

[0058] r = ((t2 - t1) × c) / 2

[0059] Where, t1 is the laser emission time, t2 is the echo reception time, and c is the propagation speed of light.

[0060] Specifically, the measured distance of the target is calculated by cross-cycle according to the following formula

[0061]

[0062] Where, r n is the measured distance of the target corresponding to the nth echo signal, r' n is the predicted distance of the corresponding target in the prediction file corresponding to the nth echo signal, R is the maximum distance that the laser ranging system can measure within the period of emitting a single laser (main wave signal), is the absolute time of the nth echo signal, is the absolute time of the mth transmitted signal, k is a non-negative integer, the laser ranging system only measures one target, but the main wave signal is emitted in pulses, so there will be multiple main wave signals and echo signals. According to the cross-cycle calculation method of the present invention, the time difference (round-trip light travel time) calculated by selecting the corresponding main wave and echo signals can achieve long-distance ranging; and here There may actually be more than one, because even after denoising, there will still be a small amount of noise data remaining. However, even so, compared with the prior art without effective denoising, the obtained ranging results are more accurate and reliable.

[0063] The calculation formula of R is

[0064] R = (c × τ) / 2

[0065] τ is the time interval between two adjacent lasers emitted by the laser ranging system, and the calculation formula is

[0066] τ = 1 / f

[0067] f is the frequency of the laser emitted by the laser transmitter.

[0068] Thread 2: Responsible for achieving high-precision filtering through coincidence counting to obtain high-precision target measurement information.

[0069] Thread 3: Responsible for real-time display of the measurement results. The abscissa of the display image of the real-time ranging module is the relative time of the main wave signal, and the ordinate is the round-trip light travel time; Thread 3 can also not be set. If set, it can more intuitively display the measurement results in real time.

[0070] The system for improving the accuracy of the laser ranging system according to the present invention, the system includes:

[0071] Signal acquisition module: Used to detect the echo photons of the laser ranging system through a superconducting nanowire single photon detector and convert them into echo signals;

[0072] Time acquisition module: Used to input the main wave signal, echo signal, 1PPS signal and GPS information emitted by the laser ranging system into different channels of the time-to-digital converter to obtain the relevant time information of the laser ranging system;

[0073] True time calculation module: Used to convert the information obtained by the time-to-digital converter into binary and separate the data to obtain control identification information, channel information and time information, and calculate the true time of each valid event according to the separated information;

[0074] Measured distance calculation module: Used to perform data filtering processing and cross-cycle calculation simultaneously in a multi-threaded parallel and shared memory manner according to the true time of the valid event and the prediction file to obtain the measured distance of the target.

[0075] The computer-readable storage medium storing one or more programs, including one or more programs including instructions, which when executed by a computing device, cause the computing device to execute any of the above methods.

Claims

1. A method for improving the accuracy of a laser ranging system, characterized in that, It includes the following steps: S1. Detect the echo photons of the laser ranging system through a superconducting nanowire single-photon detector and convert them into multiple echo signals; S2. Input the main wave signal, echo signal, 1PPS, and GPS information emitted by the laser ranging system into different channels of a time-to-digital converter to obtain the relevant time information of the laser ranging system. There are multiple channels in the time-to-digital converter that match the echo signals; S3. Convert the information obtained by the time-to-digital converter into binary and separate the data to obtain control identification information, channel information, and time information. Calculate the true time of each valid event based on the separated information, and calculate its absolute time based on the true time of each valid event; S4. Set the channel time window according to the satellite orbit prediction data, and only retain the signals within the channel time window in each echo signal channel; calculate the time difference between the signals within all channel time windows and the corresponding main wave signal as the round-trip light travel time. Arrange the time differences calculated in each echo signal channel in order, and judge whether there are time differences within the preset coincidence time window in other echo signal channels based on the time difference in any one echo signal channel. If there are, retain the time difference; otherwise, eliminate it; S5. According to the time differences and prediction files screened in step S4 of the valid events, use the multi-thread parallel and shared memory method to perform data filtering processing and cross-cycle calculation simultaneously to obtain the measured distance of the target.

2. The method for improving the accuracy of a laser ranging system according to claim 1, characterized in that: In step S2, the time-to-digital converter has one channel for the main wave signal and four channels for the echo signals.

3. The method for improving the accuracy of a laser ranging system according to claim 1, wherein: In step S2, the main wave signal and the echo signal are rising edges, and the starting moment when they reach the threshold level under the set impedance is used as the starting point for time measurement of the signal.

4. The method for improving the accuracy of the laser ranging system according to claim 1, wherein: In step S4, the information obtained by the time-to-digital converter is converted into binary, including 32-bit information. Among them, the highest 1 bit is the control identification information bit, the lowest 25 bits represent the time information bits, and the remaining 6 bits are the channel information bits.

5. The method for improving the accuracy of a laser ranging system according to claim 3, wherein: When the control identification information bit is 0, it means that the lower 31 bits represent valid time information. When the control identification information bit is 1, it means that the lower 31 bits represent time information overflow.

6. The method for improving the accuracy of a laser ranging system according to claim 1, wherein: In step S4, the absolute time of each valid event is calculated according to the following formula T rjm = T real - t 1PPS +(HH × 3600 + mm × 60 + ss + SSS × 10 -3 ) × 10 12 Among them, T rjm is the absolute time, T real is the real time, t 1PPS is the 1PPS time corresponding to the GPS time information, and HH, mm, ss, and SSS are the hour value, minute value, second value, and millisecond value in the GPS time information respectively; Calculate the true time T of each valid event according to the following formula real T real = [T″ v * N″ v + (T′ v + 1) * N′ v + T v + 1] * 1 ps Among them, T″ v is the overflow count of the overflow count value, N″ v is the time value when an overflow event occurs for the overflow count value itself, T' v is the overflow count value, N' v is the time value when the valid event time information overflows once, T v is the time information of the valid event.

7. The method for improving the accuracy of a laser ranging system according to claim 1, characterized in that: In step S4, the measured distance of the target is calculated by cross-cycle calculation according to the following formula where r n is the measured distance of the target corresponding to the nth echo signal, r' n is the predicted distance of the target corresponding to the predicted file for the nth echo signal, c is the speed of light, and R is the maximum distance that the laser ranging system can measure within the period of emitting a single laser, is the absolute time of the nth echo signal, is the absolute time of the mth transmitted signal, and k is a non-negative integer.

8. The method for improving the accuracy of a laser ranging system according to claim 1, characterized in that: R is calculated according to the following formula R = (c × τ) / 2 where τ is the time interval between two adjacent lasers emitted by the laser ranging system.

9. A system for improving the accuracy of a laser ranging system, characterized in that, The described system includes: A signal acquisition module: used to detect the echo photons of the laser ranging system through a superconducting nanowire single-photon detector and convert them into multiple echo signals; A time acquisition module: used to input the main wave signal, echo signal, 1PPS, and GPS information emitted by the laser ranging system into different channels of a time-to-digital converter to obtain the relevant time information of the laser ranging system. There are multiple channels in the time-to-digital converter that match the echo signals; Data parsing module: used to convert the information obtained by the time-to-digital converter into binary and separate the data to obtain control identification information, channel information, and time information, calculate the true time of each valid event based on the separated information, and calculate its absolute time based on the true time of each valid event; Denosing module: used to set the channel time window according to the satellite orbit prediction data, and only retain the signals within the channel time window in each echo signal channel; calculate the time difference between the signals within all channel time windows and the corresponding main wave signal as the round-trip light travel time, arrange the time differences calculated in each echo signal channel in order, and judge whether there are time differences within the preset coincidence time window in other echo signal channels based on the time difference in any one echo signal channel. If there are, retain the time difference, otherwise eliminate it; Ranging module: used to perform data filtering processing and cross-cycle calculation simultaneously to obtain the measured distance of the target by using the multi-threaded parallel and shared memory method according to the time differences and prediction files screened by the denosing module.

10. A computer-readable storage medium storing one or more programs, characterized in that: Comprising one or more programs including instructions which, when executed by a computing device, cause the computing device to perform any of the methods according to claims 1 to 8.

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