A method for self-calibration of optical tracking points of a laser communication system

Abstract

The present application relates to the technical field of wireless laser communication, and particularly relates to a self-calibration method for an optical tracking point of a laser communication system. α β The method automatically adjusts the tracking point (x α β ), and calculates the optimal value of P best at the tracking point (x α β ) by using a data statistical method based on N groups of collected power values, so that the optical tracking point of the wireless laser communication system is self-adaptive. For airborne and spaceborne laser communication equipment, the operation environment is complex, and the optical tracking point cannot be conveniently adjusted by on-site debugging personnel. The method saves the complicated steps of manual on-site parameter adjustment, and can automatically and adaptively calibrate the optical tracking point under any working environment condition. The method reduces the labor cost and greatly improves the communication stability of the equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless laser communication, and in particular to a method for self-calibration of an optical tracking point of a laser communication system. BACKGROUND

[0002] Laser communication technology is mainly applied in inter-satellite communication, satellite-ground communication and high-altitude high-speed air-based communication fields. When communicating, the transmission-reception coaxiality of the laser communication system is required to be high. Usually, the beacon and signal divergence angle of a satellite or airborne laser communication system terminal is required to be in the order of tens of micro-radians, and the transmission-reception coaxiality of the optical system needs to be controlled in the order of several micro-radians. When the laser communication terminal device is installed on a platform, the optical path micro-deformation caused by platform vibration and environmental temperature will affect the transmission-reception coaxiality of the laser communication system. The mechanical micro-deformation of the optical path may cause the actual tracking point to deviate from the tracking point calibrated on the ground. At a distance of several hundred or several thousand kilometers, two laser communication terminals complete double-end acquisition and tracking and maintain laser communication. The change of the optical tracking point directly affects the final communication quality. Therefore, self-calibration of the tracking point of the laser communication terminal is required.

[0003] The prior art CN109787686A discloses a satellite optical communication terminal in-orbit calibration and transmission-reception coaxiality correction device and method. A method of installing a calibration reflector (corner pyramid) outside a coarse pointing mechanism of a communication terminal is used to calibrate the satellite laser communication device in orbit. The method uses a 40mm inner corner pyramid with a comprehensive error of about 1.5". The signal calibration and beacon calibration transmission branch are added, which is a redundant design for the optical system. The self-emission and self-reception calibration method can theoretically recalibrate the optical tracking point of the optical system. However, since there is a certain error in the machining precision of the calibration reflector, the self-emission and self-reception calibration method cannot consider the influence of the communication distance, signal light energy intensity and atmospheric turbulence under actual working conditions, resulting in a deviation between the final calibrated optical tracking point and the actual optical tracking point.

[0004] The prior art CN114200687A discloses a novel optical self-calibration device and method for a laser communication system. The method uses three fast mirrors on the optical path to correct the parallelism of the acquisition and tracking branch, the communication transmission branch and the communication receiving branch. The center of the detector calibrated on the ground is taken as a reference. The positions of the fast mirrors are corrected to correct the optical path with micro-deformation, so as to realize self-calibration of the optical tracking point. The actual optical tracking point (x0±α, y0±β) is corrected to the position of the laboratory-calibrated optical tracking point (x0, y0) by controlling the three fast mirrors installed on the optical path. This method increases the size of the driving circuit, increases the weight, volume and power consumption of the optical-mechanical system, introduces assembly errors, and increases the development cost of the optical path. SUMMARY

[0005] The present application aims to solve the problem of optical tracking point self-calibration of a wireless laser communication system, and provides a laser communication system optical tracking point self-calibration method, which does not require a complex optical path structure, provides a fully automatic optical tracking point calibration process, and can realize optical tracking point self-calibration in the field of view of a tracking unit without redundant calibration optical paths, reduces the weight and cost of an optical-mechanical system, and can automatically calibrate the optical tracking point of an optical system in view of mechanical micro-deformation caused by platform vibration and thermal deformation, and deviation of the optical tracking point of the optical system caused by communication distance, laser energy intensity, atmospheric turbulence, and the like, can improve the stability of the communication system, optimize the energy utilization rate of laser transmission and reception of the laser communication system, and further improve the stability of data transmission.

[0006] To achieve the above-mentioned purpose, the present application provides a laser communication system optical tracking point self-calibration method, comprising the following steps:

[0007] First, optical debugging is performed, and the received signal light power value detected by a power detector of a signal light receiving unit is adjusted to a maximum value P max by adjusting a light spot tracking unit.

[0008] At this time, the light beam is reflected on the other end of the tracking detector through the light splitting sheet, and the light spot position is adjusted to the center of the light spot position detector, which is the optical tracking point (x0, y0).

[0009] Then, the laser beam is emitted by a laser emission module, and the laser beam is received by the light spot position detector and the signal light receiving unit.

[0010] The laser beam received by the light spot position detector and the signal light receiving unit is split into two parts by the light splitting sheet.

[0011] The position of the laser beam is automatically adjusted, and the light spot position is adjusted following the position of the laser beam, and the light spot position is the actual tracking point (x α , y β ).

[0012] N groups of light power values of the received signal are collected, and the optimal value of P best at the actual tracking point (x α , y β ) is calculated by using a data statistical method, and the optical tracking point self-calibration process is completed.

[0013] Among them, the optical tracking point (x0, y0) obtained in the laboratory will deviate from the optical tracking point in actual use. This is mainly manifested in the following way: after the spot position detector detects the spot position and starts the tracking function, when the spot tracking unit locks the spot position on the target surface (x0, y0) of the spot position detector, the signal light receiving unit cannot receive the maximum power value Pmax.

[0014] Specifically, the method involves collecting N sets of optical power values ​​of the received signals and calculating the optical power at the actual tracking point (x) using data statistical methods. α y β )P best The optimal value, and the specific steps to complete the self-calibration process of the optical tracking point are as follows:

[0015] In device tracking mode, enable the self-calibration function of the optical tracking point and record the optical tracking point (x0, y0) at [P]. min -P max N sets of optical power values ​​are continuously collected within the interval. The optical power value P(0,0) at the optical tracking point (x0, y0) is calculated and recorded into array M1.

[0016] The optical tracking point is stepped n*l times along the x-axis (n=1, l represents the displacement), and the optical power value P(0+n*l, 0) based on 3Σ at the tracking point (x0+n*l, y0) is calculated statistically and recorded in the array M1.

[0017] Compare whether the current power value P(0+n*l,0) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step two above. If it is greater than P nocommu If it's small, proceed to step four;

[0018] The optical tracking point is stepped n*l pixels along the x-axis (n = -1, l represents the displacement), and the optical power value P(0+n*l, 0) based on 3Σ at the tracking point (x0+n*l, y0) is calculated and recorded in the array M1.

[0019] Compare whether the current power value P(0+n*l,0) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step four above. If it is greater than P nocommu If it's small, proceed to step six;

[0020] Find the maximum received power P in the array M1 of recorded optical power.best The corresponding tracking point coordinate (x best , y0) is recorded as the X-axis optimal tracking point.

[0021] On the basis of the X-axis optimal tracking point (x best , y0), the Y-axis optimal tracking point is searched for by using the above method.

[0022] The maximum received power P best , the corresponding tracking point coordinate (x best , y best ) is recorded as the self-calibrated optimal tracking point, and the optical tracking point self-calibration process is completed.

[0023] The specific steps of searching for the Y-axis optimal tracking point by using the above method are as follows:

[0024] The optical tracking point is stepped by n*l on the y-axis (n=1, l represents the displacement amount), the optical power value P(best, 0+n*l) under the tracking point (x best , y0+n*l) is calculated and counted, and the current P(best, 0+n*l) is recorded in the array M2.

[0025] The current optical power value P(best, 0+n*l) is compared with the communication-unable power threshold P nocommu , if it is better than P nocommu , the first step is continued to be executed, and if it is smaller than P nocommu , the third step is executed.

[0026] The optical tracking point is stepped by n*l on the y-axis (n=-1, l represents the displacement amount), the optical power value P(best, 0+n*l) under the tracking point (x best , y0+n*l) is calculated and counted, and the current P(best, 0+n*l) is recorded in the array M2.

[0027] The optical power value P(0, 0) under the optical tracking point (x0, y0) is calculated and counted by using 3 times the standard deviation to calculate and count the optical power value P(0, 0) under 3Σ of the optical tracking point (x0, y0).

[0028] The number of the spot position detectors is one or two, when a beacon-free optical scanning and capturing system is used, one of the spot position detectors is used to detect the beacon light, and when a beacon light plus signal light two-level tracking scanning and capturing system is used, two of the spot position detectors are used to detect the beacon light and the signal light respectively.

[0029] The beaconless light scanning and capture system consists of a spot tracking unit, a laser emitting module, a spot position detector, and a signal light receiving unit.

[0030] This invention discloses a self-calibration method for optical tracking points in a laser communication system. This method enables the optical tracking points of wireless laser communication systems to adapt automatically. For airborne and spaceborne laser communication equipment operating in complex environments, where it is inconvenient for debugging personnel to debug optical tracking points on-site, this method eliminates the tedious steps of manual on-site parameter adjustment. The coordinates of the optical tracking point are affected by factors such as different operating temperatures, slight deformation of the equipment structure caused by vibration or temperature, different communication distances, and different light spot states. The method described in this patent can automatically and adaptively calibrate the entire optical tracking point under any operating environment conditions, reducing labor costs while greatly improving the communication stability of the equipment. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0032] Fig. 1 This is a flowchart of the self-calibration method for optical tracking points in a laser communication system according to the first embodiment of the present invention.

[0033] Fig. 2 The first embodiment of the present invention collects N sets of optical power values ​​of the received signals and calculates the optical power at the actual tracking point (x) using data statistical methods. α y β )P best The optimal value is obtained, and the specific steps of the optical tracking point self-calibration process are shown in the diagram.

[0034] Fig. 3 This is a diagram showing the specific steps of finding the optimal tracking point on the Y-axis using the above method in the first embodiment of the present invention. Detailed Implementation

[0035] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0036] First embodiment:

[0037] Please see Figs. 1 to 3 This invention provides a self-calibration method for optical tracking points in a laser communication system, comprising the following steps:

[0038] S1. First, perform optical calibration by adjusting the spot tracking unit to bring the received signal power detected by the power detector of the signal light receiving unit to its maximum value P. max .

[0039] S2. At this time, the beam will be split by the beam splitter and hit the tracking detector at the other end, adjusting the position of the light spot to the center of the light spot position detector, where the center is the optical tracking point (x0, y0).

[0040] Specifically, firstly, optical debugging is performed. By adjusting the spot tracking unit, the optical power value of the received signal detected by the power detector of the signal light receiving unit is adjusted to the maximum value Pmax. At the same time, the beam emitted from the laboratory will be hit on the tracking detector at the other end through the beam splitter. For ease of use later, ideally, the spot position at this time will be adjusted to the center of the spot position detector. The coordinates of this center are (x0, y0), and (x0, y0) is called the optical tracking point of the beaconless light scanning and capturing system.

[0041] S3. Next, the laser emitting module emits a laser beam, which is then received by the spot position detector and the signal light receiving unit.

[0042] Specifically, the number of the spot position detectors is one or two. When a beacon-less scanning and acquisition system is used, one spot position detector is used to detect the beacon light. When a two-stage tracking system of beacon light and signal light is used, two spot position detectors are used to detect the beacon light and the signal light respectively. After the two spot position detectors detect the beacon light and the signal light respectively, the optical tracking points also need to be calibrated separately. The optical tracking points include beacon light tracking points and signal light tracking points. The beacon-less scanning and acquisition system consists of a spot tracking unit, a laser emitting module, a spot position detector, and a signal light receiving unit.

[0043] S4. The laser beam received by the spot position detector and the signal light receiving unit is then split into two by the beam splitter.

[0044] S5. Automatically adjust the position of the laser beam so that the position of the light spot follows the position of the laser beam. The position of the light spot is the actual tracking point (x). α y β ).

[0045] Specifically, the optical tracking point (x0, y0) obtained during laboratory debugging will deviate from the optical tracking point during actual use. This is mainly manifested in the following way: after the spot position detector detects the spot position and activates the tracking function, when the spot tracking unit locks the spot position on the target surface (x0, y0) of the spot position detector, the signal light receiving unit cannot receive the maximum power value Pmax.

[0046] S6. Collect N sets of optical power values ​​of the received signals, and calculate the optical power at the actual tracking point (x) using data statistical methods. α y β )P best The optimal value is obtained to complete the self-calibration process of the optical tracking point.

[0047] Specifically, the method involves collecting N sets of optical power values ​​of the received signals and using statistical methods to calculate the optical power at the actual tracking point (x). α y β )P best The optimal value, and the specific steps to complete the self-calibration process of the optical tracking point are as follows:

[0048] S61. In device tracking mode, enable the self-calibration function of the optical tracking point and record the optical tracking point (x0, y0) at [P min -P max N sets of optical power values ​​are continuously collected within the interval. The optical power value P(0,0) at the optical tracking point (x0, y0) is calculated and recorded in array M1.

[0049] Specifically, in device tracking mode, the self-calibration function of the optical tracking point is enabled, and the optical tracking point (x0, y0) is recorded in [P min -P max The optical power values ​​of N consecutively collected within the interval are statistically calculated using three times the standard deviation to obtain the optical power value P(0,0) at the optical tracking point (x0, y0) and the current optical power value P(0,0) is recorded in array M1.

[0050] S62. Step n*l displacements along the x-axis of the optical tracking point (n = 1, l represents the displacement amount), statistically calculate the optical power value P(0+n*l, 0) based on 3Σ at the tracking point (x0+n*l, y0), and record the current P(0+n*l, 0) into the array M1.

[0051] S63. Compare whether the current power value P(0+n*l,0) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step two above. If it is greater than Pnocommu If it's small, proceed to step four;

[0052] S64. Step the optical tracking point n*l pixels along the x-axis (n = -1, l represents the displacement), calculate the optical power value P(0+n*l, 0) based on 3Σ at the tracking point (x0+n*l, y0), and record the current P(0+n*l, 0) into the array M1.

[0053] S65. Compare whether the current power value P(0+n*l,0) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step four above. If it is greater than P nocommu If it's small, proceed to step six;

[0054] S66. Find the maximum received power P in the array M1 of recorded optical power. best Corresponding tracking point coordinates (x best Let y0 be the optimal tracking point on the X-axis;

[0055] S67, at the optimal tracking point on the X-axis (x best Based on y0), continue to use the above method to find the optimal tracking point on the Y-axis;

[0056] Specifically, the steps for continuing to find the optimal tracking point on the Y-axis using the above method are as follows:

[0057] S671. Step n*l displacements along the y-axis of the optical tracking point (n=1, l represents the displacement amount), and statistically calculate the distance at the tracking point (x... best The optical power value P(best, 0+n*l) under y0+n*l) is recorded in array M2;

[0058] S672. Compare whether the current optical power value P(best, 0 + n*l) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with the first step above. If it is greater than P nocommu If it's small, proceed to step three.

[0059] S673. Step n*l displacements along the y-axis of the optical tracking point (n = -1, l represents the displacement amount), and statistically calculate the distance at the tracking point (x... best The optical power value P(best,0+n*l) under y0+n*l) is recorded in the array M2.

[0060] S68. Find the maximum received power P in the recorded optical power array M2. best Corresponding tracking point coordinates (x best y best This is recorded as the optimal tracking point after self-calibration. From this point on, the optical tracking point self-calibration process is complete.

[0061] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A self-calibration method for optical tracking points in a laser communication system, characterized in that, Includes the following steps: First, optical adjustments are performed by adjusting the spot tracking unit to bring the received signal power value detected by the power detector of the signal light receiving unit to its maximum value P. max ; At this time, the beam will be split by the beam splitter and hit the tracking detector at the other end, adjusting the position of the light spot to the center of the light spot position detector, which is the optical tracking point (x0, y0). Then, the laser emitting module emits a laser beam, which is received by the spot position detector and the signal light receiving unit. The laser beam received by the spot position detector and the signal light receiving unit is then split into two by the beam splitter. The position of the laser beam is automatically adjusted so that the position of the light spot follows the position of the laser beam. The position of the light spot is the actual tracking point (x). α y β ); N sets of optical power values ​​of the received signals are collected, and the optical power at the actual tracking point (x) is calculated using data statistical methods. α y β ) P best The optimal value is obtained to complete the self-calibration process of the optical tracking point.

2. The self-calibration method for optical tracking points in a laser communication system as described in claim 1, characterized in that: The optical tracking point (x0, y0) obtained during laboratory debugging will deviate from the optical tracking point during actual use. This is mainly manifested in the following way: after the spot position detector detects the spot position and activates the tracking function, when the spot tracking unit locks the spot position on the target surface (x0, y0) of the spot position detector, the signal light receiving unit cannot receive the maximum power value Pmax.

3. The self-calibration method for optical tracking points in a laser communication system as described in claim 1, characterized in that: The method involves collecting N sets of optical power values ​​of the received signals and calculating the optical power at the actual tracking point (x) using statistical methods. α y β ) P best The optimal value, and the specific steps to complete the self-calibration process of the optical tracking point are as follows: Step 1: In device tracking mode, enable the self-calibration function of the optical tracking point and record the optical tracking point (x0, y0) at [P min -P max N sets of optical power values ​​are continuously collected within the interval. The optical power value P(0,0) at the optical tracking point (x0, y0) is calculated and recorded into array M1. The second step is to step the optical tracking point by n*l displacements along the x-axis (n=1, l represents the displacement amount), statistically calculate the optical power value P(0+n*l, 0) based on 3 times the standard reference difference at the tracking point (x0+n*l, y0), and record the current P(0+n*l, 0) into the array M1. Step 3: Compare the current power value P(0+n*l,0) with the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step two above. If it is greater than P nocommu If it's small, proceed to step four; Step 4: Step the optical tracking point n*l pixels along the x-axis (n=-1, l represents the displacement), calculate the optical power value P(0+n*l, 0) based on 3 times the standard reference difference at the tracking point (x0+n*l, y0), and record the current P(0+n*l, 0) into the array M1. Step 5: Compare whether the current power value P(0+n*l,0) is less than the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with step four above. If it is greater than P nocommu If it's small, proceed to step six; Step 6: Find the maximum received power P in the array M1 of recorded optical power. best Corresponding tracking point coordinates (x best (y0), denoted as the optimal tracking point on the X-axis; Step 7: At the optimal tracking point on the X-axis (x best Based on (y0), continue to use the above method to find the optimal tracking point on the Y-axis; Step 8: Find the maximum received power P in the recorded optical power array M2. best Corresponding tracking point coordinates (x best y best This is recorded as the optimal tracking point after self-calibration. From this point on, the optical tracking point self-calibration process is complete.

4. The self-calibration method for optical tracking points in a laser communication system as described in claim 3, characterized in that: The specific steps for continuing to find the optimal tracking point on the Y-axis using the above method are as follows: Step 1: Step n*l displacements along the y-axis of the optical tracking point (n=1, l represents the displacement amount), and statistically calculate the distance at the tracking point (x... best The optical power value P(best, 0+n*l) under (y0+n*l) is recorded in array M2; The second step is to compare the current optical power value P(best, 0 + n*l) with the power threshold P that prevents communication. nocommu If it is better than P nocommu Then continue with the first step above. If it is greater than P nocommu If it's small, proceed to step three; The third step involves stepping the optical tracking point along the y-axis by n*l displacements (n=-1, l represents the displacement amount), and statistically calculating the distance at the tracking point (x... best The optical power value P(best, 0+n*l) under y0+n*l is recorded in the array M2.

5. The self-calibration method for optical tracking points in a laser communication system as described in claim 3, characterized in that: The optical power value P(0,0) calculated at the optical tracking point (x0, y0) is calculated using three times the standard deviation.

6. The self-calibration method for optical tracking points in a laser communication system as described in claim 1, characterized in that: The number of the spot position detectors is one or two. When a beacon-less scanning and capture system is used, one spot position detector is used to detect the beacon light. When a scanning and capture system with beacon light and signal light two-stage tracking is used, two spot position detectors are used to detect the beacon light and the signal light respectively.

7. The self-calibration method for optical tracking points in a laser communication system as described in claim 6, characterized in that: The beaconless light scanning and capture system consists of a spot tracking unit, a laser emitting module, a spot position detector, and a signal light receiving unit.

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