Code division multiple access based simultaneous identification method and system for multi-spot overlapping state of area array apd

Abstract

The application relates to the field of space laser communication, in particular to a face array APD multi-spot overlapping state simultaneous identification method and system based on code division multiple access, which comprises the following steps: three slave optical terminals respectively emit three beacon light beams to a master optical terminal; the three beacon light beams pass through a converging lens and converge to a 5*5 face array APD detector photosensitive surface to generate 25 APD pixel photoelectric current signals; the 25 APD pixel photoelectric current signals are input to a signal conditioning circuit, and a digital signal corresponding to each APD pixel photoelectric current signal is output; the digital signals are all input to a preprocessing unit to obtain a summary signal; the preprocessing unit inputs the summary signal to a code tracking loop to obtain an output signal; integrated processing is conducted on the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit to obtain an integrated processing result; and a centroid algorithm is used to solve the spot center position of the integrated processing result. The number of code tracking loops, the complexity and the scale of the circuit system are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of space laser communication, in particular to a method and system for simultaneously identifying a multi-spot overlapping state of a planar array APD based on code division multiple access. BACKGROUND

[0002] Space laser communication has the advantages of high communication rate, strong anti-interference ability, light and small optical terminal, good security, etc. At present, most of the research on space laser communication is based on point-to-point form, which not only affects the high-speed information transmission and relay between platforms, but also affects the construction of space-ground integrated laser communication information network. Therefore, a point-to-multipoint space laser communication technology is proposed, and the main detector of the optical terminal can simultaneously receive and detect the multi-spot formed by the laser beams emitted by multiple slave optical terminals.

[0003] However, in the prior art, since three beacon light beams from three slave optical terminals need to be code division multiple access, 75 code tracking loops are needed in the signal processing circuit system of the receiving end, which greatly increases the complexity and size of the circuit system.

[0004] Therefore, it is necessary to provide a new method and system for simultaneously identifying a multi-spot overlapping state of a planar array APD based on code division multiple access. SUMMARY

[0005] Based on the above problems existing in the prior art, the purpose of the embodiments of the present application is to provide a system for simultaneously identifying a multi-spot overlapping state of a planar array APD based on code division multiple access.

[0006] To achieve the above purpose, the technical solution adopted by the present application is: a method for simultaneously identifying a multi-spot overlapping state of a planar array APD based on code division multiple access, comprising:

[0007] S1, three slave optical terminals respectively emit three beacon light beams to the main optical terminal;

[0008] S2, the three beacon light beams pass through a converging lens to converge to a 5 5 planar array APD detector photosensitive surface to generate 25 APD pixel photoelectric current signals, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photoelectric current signal according to the optical power of the beacon light beam received by itself;

[0009] S3, the APD detector photosensitive surface inputs the 25 APD pixel photoelectric current signals generated to a signal conditioning circuit, so that the signal conditioning circuit outputs a digital signal corresponding to each APD pixel photoelectric current signal;

[0010] S4, the signal conditioning circuit inputs all the digital signals to a preprocessing unit to obtain a summary signal;

[0011] S5, the preprocessing unit inputs the summary signal to a code tracking loop to obtain an output signal;

[0012] S6, the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit are integrated to obtain an integrated processing result;

[0013] S7, the centroid algorithm is used to solve the spot center position of the integrated processing result.

[0014] Further, in S1, the three slave optical terminals respectively emit three beacon light beams to the master optical terminal, including:

[0015] The three slave optical terminals respectively emit 800nm waveband beacon light beams modulated by PRBS1, PRBS2 and PRBS3 three different format pseudo-random codes to the master optical terminal.

[0016] Further, the signal conditioning circuit includes a transimpedance amplifier and an analog-to-digital converter.

[0017] Further, the transimpedance amplifier amplifies the photocurrent signal and converts it into a voltage signal, and then the analog-to-digital converter converts the voltage signal into a digital signal.

[0018] Further, the preprocessing unit includes:

[0019] The sum result obtained by accumulating and summing the digital signal amplitudes corresponding to the photocurrent signals of the 25 APD pixels of the three beacon light beams is the summary signal.

[0020] Further, in S5, the preprocessing unit inputs the summary signal to the code tracking loop to obtain an output signal, including:

[0021] The summary signal is input to the 3-way code tracking loop to capture and track the phase of the spread spectrum baseband signal to obtain the output signal.

[0022] Further, in S6, the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit are integrated to obtain an integrated processing result, including:

[0023] The output signal output by the 3-way code tracking loop and the digital signal corresponding to the photocurrent signal of each APD pixel are integrated, including selecting 5 APD pixels contained in the fine tracking field of view and the correlation values corresponding to the respective PRBS pseudo code sequences.

[0024] The code division multiple access based face array APD multi-spot overlapping state simultaneous recognition system is applied to the code division multiple access based face array APD multi-spot overlapping state simultaneous recognition method, and the system includes:

[0025] The emission module is used for three slave optical transceivers to respectively emit three beacon light beams to a master optical transceiver;

[0026] The receiving module is used for the three beacon light beams to converge to a 5 5 two-dimensional array APD detector photosensitive surface through a converging lens, so that 25 APD pixel photocurrent signals are generated, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon light beam received by the APD pixel;

[0027] The conversion module is used for the APD detector photosensitive surface to input the 25 APD pixel photocurrent signals generated by the APD detector photosensitive surface to a signal conditioning circuit, so that the signal conditioning circuit outputs a digital signal corresponding to each APD pixel photocurrent signal;

[0028] The preprocessing module is used for the signal conditioning circuit to input all the digital signals to a preprocessing unit, so that a summary signal is obtained;

[0029] The code tracking module is used for the preprocessing unit to input the summary signal to a code tracking loop, so that an output signal is obtained;

[0030] The processing module is used for integrated processing of the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit, so that an integrated processing result is obtained;

[0031] The solving module is used for solving the center position of a light spot of the integrated processing result by using a centroid algorithm.

[0032] The method has the following beneficial effects: the method includes the following steps: three slave optical transceivers emit three beacon light beams to a master optical transceiver; the three beacon light beams converge to a 5 5 two-dimensional array APD detector photosensitive surface through a converging lens, so that 25 APD pixel photocurrent signals are generated, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon light beam received by the APD pixel; the APD detector photosensitive surface inputs the 25 APD pixel photocurrent signals generated by the APD detector photosensitive surface to a signal conditioning circuit, so that the signal conditioning circuit outputs a digital signal corresponding to each APD pixel photocurrent signal; the signal conditioning circuit inputs all the digital signals to a preprocessing unit, so that a summary signal is obtained; the preprocessing unit inputs the summary signal to a code tracking loop, so that an output signal is obtained; integrated processing of the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit is performed, so that an integrated processing result is obtained; a centroid algorithm is used to solve the center position of a light spot of the integrated processing result, so that the number of code tracking loops, the complexity and the scale of a circuit system are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0033] The application will be further described below with reference to the drawings and embodiments.

[0034] In the drawings:

[0035] Figure 1 A flow chart of a code division multiple access-based simultaneous identification method for a multi-spot overlapping state of a planar array APD is provided for Embodiment One of the application.

[0036] Figure 2 A structural schematic diagram of a code division multiple access-based simultaneous identification method for a multi-spot overlapping state of a planar array APD is provided for Embodiment One of the application.

[0037] Figure 3 A module schematic diagram of a code division multiple access-based simultaneous identification system for a multi-spot overlapping state of a planar array APD is provided for Embodiment Two of the application. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions and advantages of the embodiments of the application clearer, the technical solutions of the application will be described below in detail with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the application.

[0039] First embodiment:

[0040] The first embodiment of the application provides a code division multiple access-based simultaneous identification method for a multi-spot overlapping state of a planar array APD, which comprises: three slave optical terminals respectively emitting three beacon light beams to a master optical terminal; the three beacon light beams pass through a converging lens and converge to a 5 5 planar array APD detector photosensitive surface to generate 25 APD pixel photocurrent signals, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon light beam received by itself; the APD detector photosensitive surface inputs the generated 25 APD pixel photocurrent signals to a signal conditioning circuit to output a digital signal corresponding to each APD pixel photocurrent signal; the signal conditioning circuit inputs all the digital signals to a preprocessing unit to obtain a summary signal; the preprocessing unit inputs the summary signal to a code tracking loop to obtain an output signal; the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit are integrated to obtain an integrated processing result; a centroid algorithm is used to solve the spot center position of the integrated processing result, thereby reducing the number of code tracking loops, the complexity and scale of the circuit system.

[0041] The implementation details of the code division multiple access based planar APD multi-spot overlapping state simultaneous identification method of the present embodiment will be described below. The following implementation details are provided for the convenience of understanding and are not essential for implementing the present solution. The specific flow of the present embodiment is shown in Figs. 3 to 5, and the present embodiment is applied to a code division multiple access based planar APD multi-spot overlapping state simultaneous identification system. Figure 1 、 Figure 2

[0042] Step S1: The three slave optical transceivers respectively emit three beacon light beams to the master optical transceiver.

[0043] Specifically, in a pair of three spatial laser communication system beacon links, the three slave optical transceivers respectively emit 800 nm band beacon light beams modulated by PRBS1, PRBS2 and PRBS3 three different format pseudo random codes to the master optical transceiver. The transmitting end uses spread spectrum modulation, uses a 10-bit shift register to generate a 1023-bit pseudo code sequence, and modulates the baseband signal from 10 Kbps to 10.23 Mbps. After transmission through the spatial link, the three beacon light beams reach the master optical transceiver.

[0044] Step S2: The three beacon light beams pass through the converging lens and converge to the 5 5 planar APD detector photosensitive surface to generate 25 APD pixel photocurrent signals, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon light beam received by itself.

[0045] Specifically, after passing through the receiving end optical system of the master optical transceiver, the three beacon light beams pass through the converging lens and converge to the 5 5 planar APD detector photosensitive surface to generate 25 APD pixel photocurrent signals. At this time, the planar APD detector is in a defocused state, and the 5 APD pixels arranged in a cross shape receive the light spots.

[0046] In some examples, the receiving end optical system and the spot size are designed to control the spot to cover the 5 APD pixels arranged in a cross shape. In the coarse tracking stage of the system, at this time the spot has not completely entered the fine tracking field of view, and all the APD pixels in the planar APD detector participate in the coarse tracking process to provide a large field of view required in the coarse tracking stage. In the fine tracking stage of the system, at this time the spot has completely entered the fine tracking field of view, and the planar APD detector no longer reads the correlation values generated by the peripheral APD pixels, but only reads the 5 APD pixels covered by the spot.

[0047] Step S3: The 25 APD pixel photocurrent signals generated by the APD detector photosensitive surface are input to the signal conditioning circuit, which outputs the digital signals corresponding to each APD pixel photocurrent signal.

[0048] ​Specifically, the area array APD detector and the subsequent circuit part are both 25-way parallel processing structures. Each APD pixel in the photosensitive surface of the detector converts the received optical power into a photocurrent signal. The signal conditioning circuit includes a transimpedance amplifier and an analog-to-digital converter. In the signal conditioning circuit, the transimpedance amplifier amplifies the photocurrent signal and converts it into a voltage signal, and then the analog-to-digital converter converts the voltage signal into a digital signal.

[0049] Step S4: The signal conditioning circuit inputs all the digital signals to the preprocessing unit to obtain a summary signal.

[0050] Specifically, after the 25-way APD pixels generate photocurrent signals and the 25-way signal conditioning circuit outputs digital signals, the preprocessing unit accumulates and sums the amplitudes of the digital signals to obtain a summary signal. That is, the preprocessing unit includes a summation result obtained by accumulating and summing the amplitudes of the digital signals corresponding to the photocurrent signals of the 25-way APD pixels of the three-way beacon light beams, and the summation result is the summary signal.

[0051] Step S5: The preprocessing unit inputs the summary signal to the code tracking loop to obtain an output signal.

[0052] Specifically, the summary signal is input to the 3-way code tracking loop to capture and track the phase of the spread spectrum baseband signal, and an output signal is obtained. The code tracking loop first captures the phase of the input signal spread spectrum pseudo code sequence: the current code of the pseudo code sequence generated by the numerically controlled oscillator is correlated with the input signal spread spectrum pseudo code, and if the autocorrelation peak does not exceed the set threshold, the current code of the pseudo code sequence generated by the numerically controlled oscillator is operated in advance by half a chip, and the phase capture is completed until the correlation peak exceeds the set threshold. After capture is completed, the code tracking loop tracks the phase of the input signal spread spectrum pseudo code sequence: the leading and lagging codes of the pseudo code sequence generated by the numerically controlled oscillator are compared with the current code by half a chip in advance and lagging, respectively, the phase difference between the pseudo code signal generated by the numerically controlled oscillator and the input spread spectrum pseudo code signal is obtained through a phase discriminator, and the numerically controlled oscillator is controlled to output the pseudo code signal to track the phase of the input pseudo code signal until the leading and lagging tracking errors tend to zero, thereby realizing phase locking of the input pseudo code sequence. In addition, since the system needs to code division multiple access the beacon light modulated by three different spread spectrum baseband signals, the numerically controlled oscillator needs to include three formats of pseudo code signals PRBS1, PRBS2 and PRBS3. Since the summary signal is obtained by accumulating and summing the amplitudes of the digital signals corresponding to the photocurrent signals of the 25-way APD pixels and then input to the code tracking loop, only 3-way parallel code tracking loops are needed to realize code division multiple access of the three-way beacon light beams.

[0053] Step S6: The output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit are integrated to obtain an integrated processing result.

[0054] Specifically, the output signal of the 3-path code tracking loop and the digital signal corresponding to the APD pixel photocurrent signal of each path are integrated, including selecting 5 APD pixels contained in the fine tracking field of view and the correlation value corresponding to the respective PRBS pseudo code sequence.

[0055] Due to the design of the optical structure and the spot size, the fine tracking field of view of each spot covers 5 APD pixels and is arranged in a cross shape. Therefore, in the integrated processing, the APD pixels where each spot tracking point is located and the 4 APD pixels in the up, down, left and right directions of each APD pixel and the correlation value results of each APD pixel relative to different beacon light beams are selected, a total of 15 correlation value results, which are used for subsequent spot position solving process.

[0056] Step S7, the centroid algorithm is used to solve the spot center position of the integrated processing result.

[0057] After the integrated processing part extracts the corresponding APD pixels and correlation values of each beacon light beam, the centroid algorithm commonly used in CCD cameras is used to solve the spot center position of each beacon light beam in the photosensitive surface of the area array APD detector. Since the area array APD detector has higher bandwidth than the CCD camera, more correlation value data can be obtained in the same time, and higher position detection accuracy can be obtained.

[0058] The first embodiment of the present application provides a code division multiple access based area array APD multi-spot overlapping state simultaneous identification method, which comprises: three slave optical terminals respectively emitting three beacon light beams to a master optical terminal; the three beacon light beams pass through a converging lens and converge to 5 5 array APD detector photosensitive surface, for generating 25 APD pixel photocurrent signals, wherein each APD pixel in the APD detector photosensitive surface generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon light beam received by itself; the APD detector photosensitive surface inputs the 25 APD pixel photocurrent signals generated to the signal conditioning circuit, for outputting the digital signal corresponding to each APD pixel photocurrent signal; the signal conditioning circuit inputs all the digital signals to the preprocessing unit to obtain the summary signal; the preprocessing unit inputs the summary signal to the code tracking loop to obtain the output signal; the output signal output by the code tracking loop and the digital signal output by the signal conditioning circuit are integrated to obtain the integrated processing result; the centroid algorithm is used to solve the spot center position of the integrated processing result. The number of code tracking loops, the complexity and scale of the circuit system are reduced; the spread spectrum modulation method is used to spread the baseband signal from 10Kbps to 10.23Mbps, providing a spread spectrum gain of 30dB, and improving the receiving sensitivity of the pair of three spatial laser communication system link; the face array APD detector is used as the code division multiple access multi-spot overlapping state simultaneous identification detector, so that the photosensitive surface of the detector can bias track multiple spots, solving the problem that the tracking points of the three spots of the QD four-quadrant detector are not all in the four quadrants of the QD four-quadrant detector due to bias tracking, thereby causing the spot position detection performance to decline.

[0059] The step division of the above various methods is only for the purpose of clear description, and when implemented, one step can be combined or some steps can be split and decomposed into multiple steps, as long as the same logical relationship is included, and all are within the protection scope of the patent; adding insignificant modifications or introducing insignificant designs in the algorithm or flow, but not changing the core design of the algorithm and flow, are within the protection scope of the patent.

[0060] Second embodiment:

[0061] As Figure 3 shown, the second embodiment of the present application provides a code division multiple access based face array APD multi-spot overlapping state simultaneous identification system, which comprises a transmitting module 201, a receiving module 202, a conversion module 203, a preprocessing module 204, a code tracking module 205, a processing module 206, and a solving module 207.

[0062] Specifically, the transmitting module 201 is configured to transmit three beacon light beams from three slave optical transceivers to a master optical transceiver; the receiving module 202 is configured to converge the three beacon light beams to a 5 5 array of APD detector photosensitive surface, for its generation 25 way APD pixel photocurrent signal, wherein, according to the APD detector photosensitive surface in each APD pixel received by the beacon light beam, the corresponding APD pixel photocurrent signal is generated; conversion module 203, for the APD detector photosensitive surface will generate 25 way APD pixel photocurrent signal input to the signal conditioning circuit, for its output each way APD pixel photocurrent signal corresponding digital signal; preprocessing module 204, for signal conditioning circuit will all digital signal is input to the preprocessing unit, get the summary signal; code tracking module 205, for preprocessing unit will summary signal input to code tracking ring, get output signal; processing module 206, for the output signal of code tracking ring output and signal conditioning circuit output digital signal integrated processing, get integrated processing result; solving module 207, for using centroid algorithm to solve the integrated processing result spot center position.

[0063] It is not difficult to find that the present embodiment is a system embodiment corresponding to the first embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in the present embodiment. In order to reduce repetition, they will not be described here. Accordingly, the related technical details mentioned in the present embodiment can also be applied in the first embodiment.

[0064] It is worth mentioning that each module involved in the present embodiment is a logical module. In actual application, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, in order to highlight the innovative part of the present application, units not closely related to solving the technical problems proposed in the present application are not introduced in the present embodiment, but this does not mean that there are no other units in the present embodiment.

[0065] The above-mentioned are only embodiments of the present application, and the common knowledge of the specific structure and characteristics in the scheme is not described too much, the ordinary skilled in the art knows all the ordinary technical knowledge in the field of the present application before the application date or the priority date, can know all the prior art in the field, and has the ability to apply the conventional experimental means before the date, the ordinary skilled in the art can improve and implement the present scheme under the inspiration given by the present application, combined with their own ability, some typical known structure or known method should not become the obstacle for the ordinary skilled in the art to implement the present application. It should be pointed out that for the skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

[0066] The above-mentioned are only embodiments of the present application, and the common knowledge of the specific structure and characteristics in the scheme is not described too much, the ordinary skilled in the art knows all the ordinary technical knowledge in the field of the present application before the application date or the priority date, can know all the prior art in the field, and has the ability to apply the conventional experimental means before the date, the ordinary skilled in the art can improve and implement the present scheme under the inspiration given by the present application, combined with their own ability, some typical known structure or known method should not become the obstacle for the ordinary skilled in the art to implement the present application. It should be pointed out that for the skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

Claims

1. A method for simultaneous identification of overlapping states of multiple spots in a planar array APD based on code division multiple access, characterized in that, include: S1, the three slave optical transceivers respectively transmit three beacon beams to the master optical transceiver; S2, the three beacon beams are converged through the converging lens to 5 The photosensitive surface of the 5-sided APD detector generates 25 APD pixel photocurrent signals. Each APD pixel in the photosensitive surface of the APD detector generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon beam it receives. S3, the photosensitive surface of the APD detector will input the 25 APD pixel photocurrent signals generated to the signal conditioning circuit, so that it can output the digital signal corresponding to each APD pixel photocurrent signal. S4, the signal conditioning circuit inputs all digital signals to the preprocessing unit to obtain the summed signal; S5, the preprocessing unit inputs the summarized signal into the code tracking loop to obtain the output signal; S6 integrates the output signal from the code tracking loop and the digital signal from the signal conditioning circuit to obtain the integrated processing result. S7, the centroid algorithm is used to calculate the center position of the light spot in the integrated processing result; The preprocessing unit includes: summing the digital signal amplitudes corresponding to the photocurrent signals of the 25 APD pixels of the three beacon beams as a summary signal; The preprocessing unit inputs the summarized signal into the code tracking loop to obtain the output signal, including: The summed signal is input into a 3-way code tracking loop for phase acquisition and tracking of the spread spectrum baseband signal to obtain the output signal.

2. The method for simultaneous recognition of multiple spot overlapping states of an area array APD based on code division multiple access according to claim 1, characterized in that, In S1, the three slave optical transceivers transmit three beacon beams to the master optical transceiver, including: Three slave optical transceivers transmit 800nm ​​band beacon beams modulated by three different pseudo-random codes, PRBS1, PRBS2, and PRBS3, to the master optical transceiver.

3. The method for simultaneous identification of multiple overlapping states of a planar array APD based on code division multiple access according to claim 1, characterized in that, The signal conditioning circuit includes a transimpedance amplifier and an analog-to-digital converter.

4. The method for simultaneous identification of multiple overlapping states of a planar array APD based on code division multiple access according to claim 3, characterized in that, The transimpedance amplifier amplifies the photocurrent signal and converts it into a voltage signal, which is then converted into a digital signal by an analog-to-digital converter.

5. The method for simultaneous identification of multiple spot overlapping states of an area array APD based on code division multiple access according to claim 2, characterized in that, In S6, the output signal from the code tracking loop and the digital signal from the signal conditioning circuit are integrated and processed to obtain an integrated processing result, including: The output signals from the 3-channel tracking loop and the digital signals corresponding to the photocurrent signals of each APD pixel are integrated and processed, including selecting the correlation values ​​of the 5 APD pixels contained in the fine tracking field of view and their respective PRBS pseudocode sequences.

6. A system for simultaneous recognition of multiple overlapping states of a multi-spot APD array based on code division multiple access, characterized in that, The system applied to the method for simultaneous identification of multiple overlapping states of an area array APD based on code division multiple access as described in claim 1, comprises: The transmitting module is used for three slave optical transceivers to transmit three beacon beams to the master optical transceiver respectively; The receiving module is used to converge the three beacon beams through the converging lens to 5. The photosensitive surface of the 5-sided APD detector generates 25 APD pixel photocurrent signals. Each APD pixel in the photosensitive surface of the APD detector generates a corresponding APD pixel photocurrent signal according to the optical power of the beacon beam it receives. The conversion module is used to input the 25 APD pixel photocurrent signals generated by the photosensitive surface of the APD detector into the signal conditioning circuit, so that it can output the digital signal corresponding to each APD pixel photocurrent signal. The preprocessing module is used by the signal conditioning circuit to input all digital signals into the preprocessing unit to obtain a summary signal; wherein, the preprocessing unit includes: summing the digital signal amplitudes corresponding to the photocurrent signals of 25 APD pixels of the three beacon beams as the summary signal; The code tracking module is used by the preprocessing unit to input the summarized signal into the code tracking loop to obtain the output signal; specifically, it inputs the summarized signal into a 3-channel code tracking loop to perform phase capture and tracking of the spread spectrum baseband signal to obtain the output signal. The processing module is used to perform integrated processing on the output signal from the code tracking loop and the digital signal from the signal conditioning circuit to obtain the integrated processing result. The solution module is used to calculate the center position of the light spot in the integrated processing result using the centroid algorithm.

Images