Spaceborne lidar ground test return analog system and method

Abstract

The application provides a satellite-borne laser radar ground test echo simulation system and method, wherein a synchronous input module is used for receiving a synchronous pulse signal provided on a satellite as a timing reference of the echo simulator system; a data bus interface is used for receiving a time of a satellite to a ground surface along a laser direction at a current time forwarded on the satellite; a main wave and echo trigger module comprises an electrical synchronization unit and an optical synchronization unit; a laser module comprises a pulse laser module, a continuous laser module, a laser modulation module and a visible light indicating laser; the pulse laser module and the continuous laser module are respectively used for generating different types of laser; the visible light indicating laser is used for generating a human eye visible laser for aiming at an optical axis; a collimation aiming module comprises a collimation mirror and an aiming telescope, the collimation mirror is used for expanding and collimating output light of the laser modulation module; and the aiming telescope is used for aiming at a spot of the visible light indicating laser to receive a receiving field of view.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a ground test echo simulation system and method for spaceborne lidar, which can be used for ground testing of spaceborne ranging lidar and aerosol lidar for Earth measurement. Background Technology

[0002] Spaceborne LiDAR for Earth observation dynamically sets the echo reception time threshold based on the distance from the satellite along the laser direction to the Earth's surface. This reduces the amount of onboard echo data storage and compresses data processing time. During ground testing, the LiDAR's measurement performance, dynamic echo gate settings, and echo data processing capabilities need to be tested. Current technology cannot achieve time synchronization with onboard equipment and dynamic gate settings, thus not supporting the functional and performance testing of spaceborne LiDAR. Summary of the Invention

[0003] In view of this, the present invention provides a ground test echo simulation system for spaceborne lidar, the system comprising: a synchronization input module, a data bus interface, a main wave and echo triggering module, a laser module and a collimation aiming module;

[0004] The synchronization input module is used to receive the synchronization pulse signal provided by the satellite as a timing reference for the echo simulator system; and to send the synchronization pulse signal to the main wave and echo trigger module.

[0005] The data bus interface is used to receive the time when the satellite reaches the Earth's surface along the laser direction at the current moment, which is relayed on-board.

[0006] The main wave and echo triggering module includes an electrical synchronization unit and an optical synchronization unit; the electrical synchronization unit and the optical synchronization unit are respectively used to trigger the main wave and / or echo according to the type of the synchronization pulse signal;

[0007] The laser module includes a pulsed laser module, a continuous laser module, a laser modulation module, and a visible light indicator laser; the pulsed laser module and the continuous laser module are used to generate different types of lasers; the visible light indicator laser is used to generate the visible laser required for optical axis aiming.

[0008] The collimation and aiming module includes a collimating lens and an aiming telescope. The collimating lens is used to expand and collimate the output light of the laser modulation module. The aiming telescope is used to aim and receive the light spot of the visible light indicator laser.

[0009] Specifically, the synchronization input module is used to receive synchronization pulse signals provided by the satellite, including electrical synchronization pulse signals or optical synchronization pulse signals.

[0010] Specifically, the electrical synchronization unit generates a drive signal to trigger the simulated main wave and echo when the synchronization pulse is an electrical synchronization pulse signal, and the time interval between the echo and the main wave is the result of dynamic distance threshold calculation; the optical synchronization unit generates a drive signal to trigger the simulated echo when the synchronization pulse is an optical synchronization pulse signal, and the time interval between the echo and the optical signal is the result of dynamic distance threshold calculation; the multi-echo delay unit adds a delay to the single echo to generate a drive signal to trigger multiple echo signals.

[0011] Specifically, the pulsed laser module is used to generate pulsed laser with a pulse width in the range of ns to hundreds of ns; the continuous laser module is used to generate continuous laser with a pulse width in the range of μs to hundreds of μs, which is then converted into pulsed light by the laser modulation module; and the visible light indicator laser is used to generate visible laser light required for optical axis aiming.

[0012] Specifically, the optical axes of the collimating lens and the aiming telescope are parallel.

[0013] Specifically, the system also includes a dynamic distance threshold calculation module, which converts the distance from the satellite along the laser direction to the Earth's surface at the current moment into the time of the main wave and the echo.

[0014] This invention also proposes a method for simulating ground test echoes of spaceborne lidar, applied in the aforementioned spaceborne lidar ground test echo simulation system. This method includes the following steps:

[0015] Step S1: Use a visible light indicating laser to align the collimating lens optical axis of the echo simulation system with the receiving field of view of the on-board lidar;

[0016] Step S2: Select the working mode according to the type of synchronization pulse signal, wherein the synchronization pulse signal includes an electrical synchronization pulse signal or an optical synchronization pulse signal; the working mode includes an electrical synchronization mode or an optical synchronization mode.

[0017] Step S3: According to the different synchronization modes, after receiving the synchronization pulse, the echo simulation system sends it to the corresponding synchronization unit of the main wave and echo trigger module; the corresponding synchronization unit generates the main wave and echo trigger pulse based on the synchronization signal.

[0018] Step S4: Based on the range of the main wave and echo pulse widths, select whether to use a pulsed laser or a continuous laser to generate different types of lasers.

[0019] Specifically, in step S2, when the synchronization pulse signal is an electrically synchronized pulse signal, the echo simulation system operates in electrically synchronized mode; in step S3, after receiving the synchronization pulse, the echo simulation system sends it to the electrically synchronized unit of the main wave and echo trigger module; this unit generates the main wave and echo trigger pulse based on the synchronization signal, and the time difference between the first pulse of the main wave and the first pulse of the echo is the time T it takes for the satellite to reach the Earth's surface along the laser pointer. By adding a pulse after the echo trigger pulse, the echo can be set to have the effect of multiple pulse superposition.

[0020] Specifically, in step S2, when the synchronization pulse signal is an optical synchronization pulse signal, the echo simulation system operates in optical synchronization mode; in step S3, after receiving the optical synchronization signal, the echo simulation system sends it to the optical synchronization unit of the main wave and echo trigger module; based on the synchronization signal, this unit generates an echo trigger pulse after a delay of T according to the time T it takes for the satellite to reach the ground along the laser pointer; by adding a pulse after the echo trigger pulse, the echo can be set to have the effect of multiple pulse superposition.

[0021] Specifically, in step S4, the pulsed laser is used to generate pulsed laser with a pulse width in the range of ns to hundreds of ns, and the laser output is sent to the collimating lens after attenuation; the continuous laser module is used to generate continuous laser with a pulse width in the range of μs to hundreds of μs. In order to simulate the effect of multiple echo superposition, it needs to be pulse-modulated by the laser modulator, and the modulated laser is sent to the collimating lens after attenuation.

[0022] Beneficial effects:

[0023] 1) Through the implementation of the system in this invention, the ability to synchronize with the time and dynamic echo of on-board equipment can be achieved, and the function and performance testing of on-board lidar can be supported;

[0024] 2) In the system of this invention, the pulsed laser module and the continuous laser module are used to generate different types of lasers, realizing the generation of different types of lasers and having wide adaptability;

[0025] 3) In the system of the present invention, the electrical synchronization unit and the optical synchronization unit are respectively used to trigger the main wave and / or echo according to the type of the synchronization pulse signal, so as to adapt to echo testing in various scenarios;

[0026] 4) In the system of this invention, the visible light indicating laser is used to generate the visible laser required for optical axis aiming. The visible light indicating laser is used to align the optical axis of the collimating lens of the echo simulation system with the receiving field of view of the on-board laser radar. The system is easy to operate and not prone to errors. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the ground test echo simulation system for spaceborne lidar in this invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] This invention provides a ground-based test echo simulation system for spaceborne lidar, such as... Figure 1 As shown, it includes a synchronous input module, a data bus interface, a dynamic distance threshold calculation module, a main wave and echo trigger control module, a laser modulation module, and an output collimation module.

[0030] Synchronization Input Module: Used to receive electrical or optical synchronization pulse signals provided by the satellite, serving as the timing reference for the echo simulator system. The devices within the synchronization input module for processing the optical synchronization pulse signals include a detector and a signal amplification unit, used to convert the optical signal into an electrical signal.

[0031] Data bus interface: Used to receive the current time when the satellite reaches the Earth's surface along the laser direction, relayed from the satellite.

[0032] Dynamic distance threshold calculation module: converts the distance from the satellite along the laser direction to the Earth's surface at the current moment into the time of the main wave and the echo.

[0033] Main Wave and Echo Trigger Module: This module includes an electrical synchronization unit, an optical synchronization unit, and a multi-echo delay unit. The electrical synchronization unit generates drive signals to trigger the simulated main wave and echo when the synchronization pulse is an electrical signal; the time interval between the echo and the main wave is calculated based on the dynamic distance threshold. The optical synchronization unit generates drive signals to trigger the simulated echo when the synchronization pulse is an optical signal; the time interval between the echo and the optical signal is calculated based on the dynamic distance threshold. The multi-echo delay unit adds a delay to a single echo, generating drive signals to trigger multiple echo signals.

[0034] Laser Module: The laser modulation module includes a pulsed laser module, a continuous laser module, a laser modulation module, and a visible light indicator laser. The pulsed laser module is used to generate pulsed lasers with pulse widths in the range of ns to hundreds of ns. The continuous laser module is used to generate continuous lasers with pulse widths in the range of μs to hundreds of μs, which are then converted into pulsed light by the laser modulation module. The visible light indicator laser is used to generate visible laser light required for optical axis aiming.

[0035] Collimation and aiming module: includes a collimating lens and an aiming telescope. The collimating lens expands and collimates the output light of the laser modulation module; the aiming telescope is used to aim the spot of the visible light indicator laser into the receiving field of view; the optical axes of the collimating lens and the aiming telescope are parallel.

[0036] This invention also proposes a method for simulating the ground test echo of a spaceborne lidar in a ground test echo simulation system, comprising the following steps:

[0037] Step S1: First, use a visible light indicating laser to align the collimating lens optical axis of the echo simulation system with the receiving field of view of the on-board lidar;

[0038] Step S2: Then select the working mode according to the synchronization type, and select the working mode according to the type of synchronization pulse signal, wherein the synchronization pulse signal includes an electrical synchronization pulse signal or an optical synchronization pulse signal; the working mode includes an electrical synchronization mode or an optical synchronization mode.

[0039] Step S3: When operating in electrical synchronization mode, after receiving the synchronization pulse, the echo simulation system sends it to the electrical synchronization unit of the main wave and echo trigger module. Based on the synchronization signal, this unit generates the main wave and echo trigger pulses. The time difference between the first pulse of the main wave and the first pulse of the echo is the time T it takes for the satellite to reach the Earth's surface along the laser pointer. By adding pulses after the echo trigger pulse, the echo can be set to have the effect of multiple pulse superposition.

[0040] When operating in optical synchronization mode, the echo simulation system receives the optical synchronization signal and sends it to the optical synchronization unit of the main wave and echo trigger module. Based on the synchronization signal, this unit generates an echo trigger pulse after a delay of T, according to the time T it takes for the satellite to reach the Earth's surface along the laser beam. By adding a pulse after the echo trigger pulse, the echo can be set to have multiple pulses superimposed.

[0041] Step S4: Based on the range of the main wave and echo pulse widths, select whether to use a pulsed laser or a continuous laser. A pulsed laser is used to generate pulsed lasers with pulse widths in the range of ns to hundreds of ns; the laser output is attenuated before being sent to a collimating lens. A continuous laser module is used to generate continuous lasers with pulse widths in the range of μs to hundreds of μs. To simulate the effect of multiple echo superposition, pulse modulation is required using a laser modulator; the modulated laser is attenuated before being sent to a collimating lens.

[0042] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0043] It will be apparent to those skilled in the art that the embodiments of the present invention are not limited to the details of the exemplary embodiments described above, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the embodiments of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the embodiments of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be encompassed within the embodiments of the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules, or devices recited in the system, apparatus, or terminal claims may also be implemented by the same unit, module, or device through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the embodiments of the present invention should not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ground-based test echo simulation system for spaceborne lidar, characterized in that, The system includes: a synchronization input module, a data bus interface, a main wave and echo trigger module, a laser module, and a collimation and aiming module; The synchronization input module is used to receive the synchronization pulse signal provided by the satellite as a timing reference for the echo simulator system; and to send the synchronization pulse signal to the main wave and echo trigger module. The data bus interface is used to receive the time when the satellite reaches the Earth's surface along the laser direction at the current moment, which is relayed on-board. The main wave and echo triggering module includes an electrical synchronization unit and an optical synchronization unit; the electrical synchronization unit and the optical synchronization unit are respectively used to trigger the main wave and / or echo according to the type of the synchronization pulse signal; The laser module includes a pulsed laser module, a continuous laser module, a laser modulation module, and a visible light indicator laser; the pulsed laser module and the continuous laser module are used to generate different types of lasers; the visible light indicator laser is used to generate the visible laser required for optical axis aiming. The collimation and aiming module includes a collimating lens and an aiming telescope. The collimating lens is used to expand and collimate the output light of the laser modulation module; the aiming telescope is used to aim the light spot of the visible light indicator laser into the receiving field of view. The synchronization input module is used to receive synchronization pulse signals provided by the satellite, including electrical synchronization pulse signals or optical synchronization pulse signals. The electrical synchronization unit generates a drive signal to trigger the simulated main wave and echo when the synchronization pulse is an electrical synchronization pulse signal. The time interval between the echo and the main wave is the result of dynamic distance threshold calculation. The optical synchronization unit generates a drive signal to trigger the simulated echo when the synchronization pulse is an optical synchronization pulse signal. The time interval between the echo and the optical signal is the result of dynamic distance threshold calculation. The multi-echo delay unit adds a delay to the single echo and generates a drive signal to trigger multiple echo signals. The pulsed laser module is used to generate pulsed laser with a pulse width in the range of ns to hundreds of ns; the continuous laser module is used to generate continuous laser with a pulse width in the range of μs to hundreds of μs, which is then converted into pulsed light by the laser modulation module; the visible light indicator laser is used to generate visible laser light required for optical axis aiming.

2. The ground test echo simulation system for spaceborne lidar as described in claim 1, characterized in that: The optical axes of the collimating lens and the aiming telescope are parallel.

3. The ground test echo simulation system for spaceborne lidar as described in claim 1 or 2, characterized in that: The system also includes a dynamic distance threshold calculation module, which is used to convert the distance from the satellite along the laser direction to the Earth's surface at the current moment into the time of the main wave and the echo.

4. A method for simulating ground-based test echoes of a spaceborne lidar, applied in the spaceborne lidar ground-based test echo simulation system as described in claim 3, characterized in that: The method includes the following steps: Step S1: Use a visible light indicating laser to align the collimating lens optical axis of the echo simulation system with the receiving field of view of the on-board lidar; Step S2: Select the working mode according to the type of synchronization pulse signal, wherein the synchronization pulse signal includes an electrical synchronization pulse signal or an optical synchronization pulse signal; the working mode includes an electrical synchronization mode or an optical synchronization mode. Step S3: According to the different synchronization modes, after receiving the synchronization pulse, the echo simulation system sends it to the corresponding synchronization unit of the main wave and echo trigger module; the corresponding synchronization unit generates the main wave and echo trigger pulse based on the synchronization signal. Step S4: Based on the range of the main wave and echo pulse widths, select whether to use a pulsed laser or a continuous laser to generate different types of lasers.

5. The method for simulating ground test echoes of a spaceborne lidar as described in claim 4, characterized in that: In step S2, when the synchronization pulse signal is an electrically synchronized pulse signal, the echo simulation system operates in electrically synchronized mode; in step S3, after receiving the synchronization pulse, the echo simulation system sends it to the electrically synchronized unit of the main wave and echo trigger module. Based on the synchronization signal, this unit generates a main wave and an echo trigger pulse. The time difference between the first pulse of the main wave and the first pulse of the echo is the time T it takes for the satellite to travel along the laser pointer to the Earth's surface. By adding a pulse after the echo trigger pulse, the echo can be set to have the effect of multiple pulses superimposed.

6. The method for simulating ground test echoes of a spaceborne lidar as described in claim 4, characterized in that: In step S2, when the synchronization pulse signal is an optical synchronization pulse signal, the echo simulation system operates in optical synchronization mode; in step S3, after receiving the optical synchronization signal, the echo simulation system sends it to the optical synchronization unit of the main wave and echo trigger module; based on the synchronization signal, this unit generates an echo trigger pulse after a delay of T according to the time T it takes for the satellite to reach the ground along the laser pointer; by adding a pulse after the echo trigger pulse, the echo can be set to have the effect of multiple pulse superposition.

7. The method for simulating ground test echoes of a spaceborne lidar as described in claim 4, characterized in that: In step S4, the pulsed laser is used to generate pulsed laser with a pulse width in the range of ns to hundreds of ns. The laser output is sent to the collimating lens after attenuation. The continuous laser module is used to generate continuous laser with a pulse width in the range of μs to hundreds of μs. In order to simulate the effect of multiple echo superposition, it is necessary to perform pulse modulation through a laser modulator. The modulated laser is sent to the collimating lens after attenuation.

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