Array-type spaceborne lidar measurement method in multiple transmit and receive mode

Abstract

The present invention discloses a measurement method of an array-type spaceborne lidar in a multiple-transmitter and multiple-receiver mode, belonging to the technical field of radar measurement and used for spaceborne lidar measurement. It includes designing an array mode of the sub-satellite footprints of N satellites over the ocean, designing an array-type field stop, where N aperture holes on the array-type field stop correspond to the positions of N footprints under each satellite; installing the array-type field stop at the receiving end of each spaceborne lidar, launching the satellites to form an array mode of the sub-satellite footprints; making each lidar synchronously transmit laser signals, and each lidar synchronously receives the echo signals of N spaceborne lidars through its respective field stop. The present invention greatly enriches the acquisition amount of effective information, significantly improves the signal-to-noise ratio of the received signals, and the signal-to-noise ratio is N times that of the common single-lidar satellite, so that the detection accuracy and efficiency of the lidar in a complex ocean environment are significantly improved.

Description

Technical Field

[0001] The present invention discloses a measurement method for an arrayed spaceborne lidar in a multiple transmission and multiple reception mode, belonging to the technical field of radar measurement. Background Art

[0002] Existing lidar satellites are all single-satellite systems, usually operating in high orbits from the ground up to 700 km. During the transmission of laser through the atmosphere and the ocean, a large amount of energy is lost, which poses high requirements for the laser emission energy and the receiving system of the satellite. Especially for spaceborne lidars for ocean exploration, since the scattered signals below the sea surface are very weak, the inversion of ocean optical parameters and the ocean exploration ability pose even higher requirements for the received signal intensity. Due to the limitations of the hardware conditions of the transmission and reception systems, the laser energy emitted by current lidar satellites is limited, and the loss of optical energy during the laser transmission process is inevitable, resulting in a rapid decrease in energy density during long-distance transmission, affecting the detection ability and accuracy. At the same time, due to the limitation of the area of the receiving telescope, the intensity of the laser echo signal obtained by the spaceborne lidar receiving system is insufficient, reducing the signal-to-noise ratio and detection range of the system. In addition, due to the characteristics of the satellite platform and the requirements of the observation mission, the transit time and the accumulation time are often short, further exacerbating the problem of insufficient energy of the received echo signal. The combined effect of these factors leads to the difficulty for the spaceborne lidar to obtain sufficient energy at the receiving end to meet the requirements of high-precision detection, and the penetration depth of seawater is limited, severely affecting the detection ability of the ocean profile. Summary of the Invention

[0003] The purpose of the present invention is to provide a measurement method for an arrayed spaceborne lidar in a multiple transmission and multiple reception mode to solve the problem of insufficient echo energy in the measurement of spaceborne lidars in the prior art.

[0004] The measurement method for an arrayed spaceborne lidar in a multiple transmission and multiple reception mode includes designing an array pattern of the sub-satellite spots of satellites over the ocean, designing an arrayed field stop, and the aperture holes on the arrayed field stop correspond to the spots of each satellite; installing the arrayed field stop at the receiving end of each spaceborne lidar, launching the satellites into the air to form an array pattern of sub-satellite spots; making each lidar synchronously emit laser signals, and each lidar synchronously receives the echo signals of

[0005] The array pattern of the sub-satellite spots includes lidar satellites, and each lidar is equipped with a field stop with aperture holes, The laser radar satellites adopt a time synchronization mechanism, dynamically adjust the time synchronization parameters by establishing an inter-satellite high-speed communication link, and correct the time difference between satellites.

[0006] All satellites are deployed in the same orbital plane and distributed along the orbital circumference. The actual operating distance between satellites is not less than the minimum safe distance between satellites. , the number of onboard lidar satellites The maximum value of The ground resolution of the satellite array , Satellite minimum safety distance , Satellite orbit height and the radius of the Earth Sure.

[0007] The minimum distance between each satellite's subsatellite spot in the ocean for:

[0008] ;

[0009] According to the satellite array's sub-satellite spot array range in the ocean, the number of satellites covering the sub-satellite spot array range is calculated as .

[0010] Calculate the maximum number of satellites per row based on length and width , the maximum number of satellites in each column ,get :

[0011] .

[0012] Minimum spacing of aperture holes on an array field diaphragm for:

[0013] ;

[0014] In the formula, is the focal length of the satellite receiving unit telescope.

[0015] The diameter of the aperture on the array field diaphragm is :

[0016] ;

[0017] In the formula, is the ocean spot diameter.

[0018] The array pattern of the sub-satellite light spots is a first-layer satellite array. A second-layer satellite array is constructed above the first-layer satellite array. The sub-satellite light spot array of the second-layer satellite array is within the sub-satellite light spot array of the first-layer satellite array.

[0019] When the sub-satellite spot array of the satellite array in the ocean is rectangular, calculate the first layer of the satellite array according to the length and width :

[0020] .

[0021] The maximum number of spaceborne lidar satellites in the second layer of the satellite array is :

[0022] ;

[0023] The maximum total number of satellites in the satellite array with two-layer staggered layout is:

[0024] .

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention designs a cooperative working mechanism for the lidar satellite array of "simultaneous transmission and reception, multiple transmissions and multiple receptions", realizing that the transmitted energy of the satellite observation system is times that of a single satellite, and the received signal energy is times that of a single satellite, times that of an ordinary multi-satellite array of "multiple transmissions and single reception", greatly enriching the acquisition of effective information and solving the problem of weak ocean signals in the spaceborne lidar system;

[0027] (2) The mode of multi-satellite cooperative work in the present invention also significantly improves the signal-to-noise ratio of the received signal, which is times that of a common single lidar satellite, and is times that of an ordinary multi-satellite array of "multiple transmissions and single reception", times that of an ordinary multi-satellite array of "multiple transmissions and single reception", significantly improving the detection accuracy and efficiency of lidar in complex ocean environments;

[0028] (3) The present invention designs an array-type field-of-view diaphragm in the receiving unit according to the requirements of the cooperative working mechanism, enabling each satellite to receive the laser echo signals of satellites. The number of diaphragm holes and the relative positions between the holes of the field-of-view diaphragm correspond one-to-one with the number of satellites in the satellite array and the relative positions of the sub-satellite spots. The aperture and spacing of the diaphragm are determined by the focal length of the receiving telescope, the satellite orbital altitude, the diameter and spacing of the sub-satellite point spots;

[0029] ​(4) The present invention designs a satellite deployment framework for a lidar satellite array based on a collaborative working mechanism, and the deployment of satellites in the array follows specific spatial constraints. The satellites can be deployed at the same orbital altitude or designed for a two-layer staggered deployment with different orbital altitudes. The maximum number of satellites at a single orbital altitude is determined by the satellite orbital altitude, the ground resolution of the satellite array, and the minimum safe distance between satellites. When deploying in two layers in a staggered manner, the sub-satellite spot array of the second-layer satellite array is within the sub-satellite spot array of the first-layer satellite array; when using a grid array, the satellites in the second layer are deployed at the midpoints of the diagonals of the first-layer satellite grid, and the maximum number of satellites in each row and column is one less than that of the first layer. Without changing the ground resolution of the satellite array, the two-layer staggered deployment can increase the number of satellites and further improve the total energy and signal-to-noise ratio of the laser echo signal;

[0030] (5) The redundancy design and fault detection mechanism of the present invention ensure the stable operation and long-term reliability of the radar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the emission and reception of laser pulse signals for the "multiple transmit and multiple receive" spaceborne lidar array system of the present invention;

[0032] Figure 2 Schematic diagram of the emission and reception of laser pulse signals for a common "multiple transmit and single receive" spaceborne lidar array system;

[0033] Figure 3 Schematic diagram of the receiving unit of a single satellite in the spaceborne lidar array system of the present invention;

[0034] Figure 4 Schematic diagram of the energy received by the spaceborne lidar array system of the present invention varying with the number of satellites;

[0035] Figure 5 Schematic diagram of the signal-to-noise ratio of the spaceborne lidar array system of the present invention varying with the number of satellites;

[0036] Figure 6 Schematic diagram of the two-layer staggered deployment design distribution of the spaceborne lidar array system of the present invention, taking the deployment of 9 satellites in the first layer ( ) as an example;

[0037] Figure 7 Block diagram of the composition principle of the lidar system of a single satellite in the spaceborne lidar array system of the present invention.

[0038] The reference numerals include: 1 - laser emission unit, 2 - emission control unit, 3 - telescope, 4 - array-type field stop, 5 - detection and acquisition unit. DETAILED DESCRIPTION OF THE INVENTION

[0039] To make the objectives, technical solutions and advantages of the present invention clearer, the following describes the technical solutions in the present invention clearly and completely. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0040] The measurement method of an array-type spaceborne lidar in a multiple transmit and receive mode includes designing the array mode of the sub-satellite spots of satellites over the ocean, designing an array-type field stop 4, and the aperture holes on the array-type field stop 4 correspond to the spot positions under each satellite; installing the array-type field stop 4 at the receiving end of each spaceborne lidar, launching the satellites to form the array mode of the sub-satellite spots; making each lidar synchronously emit laser signals, and each lidar synchronously receives the echo signals of the spaceborne lidars through its own field stop.

[0041] The array mode of the sub-satellite spots includes laser radar satellites, and each lidar is equipped with a field stop with aperture holes. The

[0042] laser radar satellites adopt a time synchronization mechanism, and dynamically adjust the time synchronization parameters by establishing an inter-satellite high-speed communication link to correct the time difference between satellites. All satellites are deployed in the same orbital plane and distributed circumferentially along the orbit. The actual running distance between each satellite is not less than the minimum safe distance of the satellite The maximum value of is determined by the ground resolution of the satellite array, the minimum safe distance of the satellite, the orbital altitude of the satellite and the radius of the earth.

[0043] The minimum distance between the sub-satellite spots of each satellite over the ocean is:

[0044] ;

[0045] According to the sub-satellite spot array range of the satellite array over the ocean, calculating the number of satellites covering the sub-satellite spot array range is .

[0046] Calculate the maximum value of the number of satellites in each row and the maximum value of the number of satellites in each column , obtain :

[0047] 。

[0048] The minimum distance between the diaphragm holes on the array-type field diaphragm 4 is:

[0049] ;

[0050] wherein, is the focal length of the telescope of the satellite receiving unit.

[0051] The diameter of the diaphragm hole on the array-type field diaphragm 4 is :

[0052] ;

[0053] wherein, is the sub-satellite spot diameter.

[0054] The array of the sub-satellite spot array mode is the first-layer satellite array, and a second-layer satellite array is constructed above the first-layer satellite array, and the sub-satellite spot array of the second-layer satellite array is within the sub-satellite spot array of the first-layer satellite array.

[0055] When the sub-satellite spot array of the satellite array is rectangular in the ocean, calculate the of the first-layer satellite array according to the length and width:

[0056] 。

[0057] The maximum number of spaceborne lidar satellites in the second-layer satellite array is :

[0058] ;

[0059] The maximum value of the total number of satellites in the two-layer interleaved satellite array is:

[0060] 。

[0061] The signal reception of the spaceborne lidar array system of the present invention is as Figure 1 shown. To achieve the "multiple transmit and multiple receive" collaborative working mechanism, each satellite of the spaceborne lidar array system is equipped with an independent transmitting and receiving system for the ocean lidar. satellites coordinate and simultaneously emit laser pulses through the synchronization mechanism of the emission control unit 2, that is laser pulses; at the same time, the receiving unit of the lidar system of each satellite uses the array-type field diaphragm 4 to simultaneously receive The echo signals of a beam of laser pulses, that is, each satellite receives an echo signal. The cooperative working mode designed in the present invention is different from the working mode of an ordinary "multiple transmission and single reception" satellite array, which is mainly reflected in the reception of lidar echo signals. For example, Figure 2 as shown, each satellite simultaneously emits a beam of laser pulses, and each satellite only receives its own laser echo signal. Using the cooperative working mode of "simultaneous transmission and reception, multiple transmission and multiple reception" can effectively increase the total energy of the received echo signals.

[0062] When all satellites are deployed in the same orbital plane and are distributed circumferentially along the orbit, and the actual operating distance between each satellite node is always greater than the minimum safety distance threshold designed for the system ( ), the minimum number of satellites in the array is 2, and the maximum number is determined by the ground resolution of the satellite array , , the satellite orbital altitude . Specifically, when the spaceborne lidar emits laser pulses to the ocean, the light beam is perpendicular to the Earth's surface. When all satellites in the array are at the same orbital altitude, since the satellite spacing and the sub-satellite point spot spacing are much smaller than the Earth's radius and the satellite orbital altitude, the two satellites and the Earth's center, as well as the sub-satellite point spots of these two satellites and the Earth's center, can be regarded as two similar triangles.

[0063] Taking the ground resolution of the satellite array as GSD as an example, the sub-satellite point spot of the satellite array covers a square area on the ground. Using the minimum interval of the spot on the ocean, the maximum number of satellites in the array is obtained:

[0064] ;

[0065] In the formula, is the maximum number of satellites in each row and each column.

[0066] When the satellite orbit is designed as , the ground resolution of the satellite array is , referring to the minimum satellite interval of the current high-resolution synthetic aperture radar in the sun-synchronous orbit, the Earth's radius , according to the above calculation formula, the minimum interval of the laser spot on the ocean, and the maximum value of , the maximum number of satellites satellites.

[0067] For example, Figure 3As shown, taking one satellite in the array as an example, the receiving working mode of the echo signal is demonstrated. The echo signals of the laser pulses simultaneously emitted by the spaceborne lidar array system enter the telescope of the receiving system. Subsequently, the echo signals collected by the telescope are transmitted to the array field stop 4, which is used to receive all the echo signals simultaneously. The geometric arrangement of the aperture array corresponds to the satellite arrangement layout. The spatial arrangement of the aperture diameters can be determined by the satellite array layout set before launch. This corresponding relationship ensures that each satellite receives echo signals simultaneously, and they are accurately matched and efficiently separated, avoiding mutual interference of different spot signals. The echo signals passing through the array field stop 4 then enter the detection and acquisition unit for acquisition and storage. The calculated minimum spacing of the laser spots in the ocean , the currently commonly used , the diameter of the spot under the satellite , calculated and .

[0068] Each lidar receiving unit of the satellites in the spaceborne lidar array of the present invention has a unique array field stop 4. Without loss of generality, taking the spaceborne lidar array system composed of lidar satellites with collaborative observation capabilities as an example, the field stop is composed of aperture holes, and are the number of rows and columns of the aperture holes respectively, that is, the number of satellites in each row and each column of the satellite array. Therefore, the number of aperture holes of the field stop is the same as the number of satellites in the satellite array. The distance between the aperture holes of the array field stop is determined by the spacing of the spots under the satellite.

[0069] As the core key component to achieve the collaborative working mechanism, the array field stop 4 can not only enable each satellite to receive all the laser pulse echo signals of all satellites, but also optimize the light transmission efficiency and detection accuracy. While reducing the background noise, it avoids the overlapping interference of adjacent echo signals and demonstrates excellent performance.

[0070] The laser pulse energy emitted by each single satellite of the spaceborne lidar array system is , laser pulses simultaneously emitted by the array system composed of satellites in a very short time, is the total energy of times that of a single satellite, greatly enhancing the emitted laser energy, successfully breaking through the physical limit of the emission energy of a single satellite, and achieving times enhancement of the emission energy.

[0071] Such asFigure 4 As shown, it shows the relationship between the total energy of the echo signals received by the spaceborne lidar array system of the present invention and the ordinary multi-satellite array and the number of satellites. In the spaceborne lidar array system of the present invention, the receiving unit of each satellite can not only receive the echo signal of the laser pulse emitted by itself, but also receive the echo signal of the laser pulse emitted by other satellites in the system, that is, the receiving unit of each satellite can receive echo signals of laser pulses. If the energy of a beam of laser echo signal is ,then the total energy of the received echo signal :

[0072] ;

[0073] Among them, The accumulation of represents the energy of the echo signals of laser pulses received by each satellite, and the accumulation of represents The sum of the energies received by satellites.

[0074] The cooperative working mode of the spaceborne lidar array system is different from that of the ordinary multi-satellite array, which is mainly reflected in the reception of lidar echo signals. The working mode of the ordinary multi-satellite array composed of satellites is the independent working mode of "multiple transmissions and single reception". Each satellite only receives its own laser echo signal, and the total energy of the received echo signal :

[0075] .

[0076] Therefore, the total echo signal energy that the spaceborne lidar array system of the present invention can receive is times that of the echo signal energy received by a single satellite, and is times that of the signal energy received by an ordinary multi-satellite array with the working mechanism of "multiple transmissions and single reception". times.

[0077] As Figure 5 shown, it shows the relationship between the signal-to-noise ratio of the spaceborne lidar array system of the present invention and the ordinary multi-satellite array and the number of satellites. The signal-to-noise ratio SNR is the ratio between the signal intensity and the noise intensity, usually expressed in decibels (dB). The signal-to-noise ratio of a single "single transmission and single reception" lidar is expressed as:

[0078] ;

[0079] In the formula, is the energy of the echo signal of the laser pulse;

[0080] In contrast, the total noise intensity that can be received by the spaceborne lidar array system designed based on the collaborative working mechanism of the present invention is:

[0081] ;

[0082] The signal-to-noise ratio of the present invention is:

[0083] ;

[0084] It can be seen that the result of the signal-to-noise ratio is increased by times compared with the signal-to-noise ratio of a single "single transmit and single receive" satellite. Different from the spaceborne lidar array system working in a collaborative manner, for satellites operating in the "multiple transmit and single receive" working mechanism of ordinary multi-satellite arrays, there is a lack of collaboration between satellites, and the noise intensity is expressed as:

[0085] ;

[0086] At this time, its signal-to-noise ratio is expressed as:

[0087] ;

[0088] The spaceborne lidar array system working in a collaborative manner has a signal-to-noise ratio that is increased by times compared with that of an ordinary multi-satellite array with the "multiple transmit and single receive" working mechanism. Obviously, while obtaining more effective information, the signal-to-noise ratio of the acquired signal is also increased. times.

[0089] The satellite array layout of the spaceborne lidar array system can not only be arranged at the same orbital altitude, but can also be designed as a two-layer staggered layout structure. At this time, the orbital altitudes of the two layers of satellites are different, but the difference in orbital altitude between the two layers of satellites is much smaller than the orbital altitude of the earth and the radius of the earth, and can be ignored. The satellites in the second layer are arranged at the midpoint of the diagonal of the satellite grid in the first layer. Therefore, the number of satellites in each row and each column of the satellite array in the second layer is one less than that in the first layer. The maximum number of satellites in each orbital plane is also determined by the ground resolution of the satellite array, the minimum distance between satellites, the orbital altitude of the satellites, and the radius of the earth.

[0090] As Figure 6 shown, with 9 satellites arranged in the first layer ( Taking [Example] as an example, the two-layer staggered layout design of the lidar satellite array is demonstrated. The satellite array layout of the present invention can not only be arranged in a single layer within the same operating orbital plane, but also be designed in a staggered layout, that is, the satellites in the array are placed on two orbital planes with different satellite orbital heights. The placement of the two layers of satellites both follows the single-layer layout design. The satellites in the second layer are placed at the midpoint of the diagonal of the satellite grid in the first layer. The number of satellites in the two-layer staggered satellite array is at least 5 (4 in the first layer and 1 in the second layer), and the maximum value ( is determined by the ground resolution of the satellite array , , satellite orbital height . Since the difference in orbital heights between the two layers of satellites is much smaller than the Earth's orbital height and the Earth's radius and can be ignored, the minimum interval of the laser sub-satellite point spots of the second-layer satellites on the ocean is also . The maximum number of satellites in the first layer is [Number]. Since the second-layer satellites are located at the midpoint of the diagonal of the satellite grid in the first layer, the maximum number of satellites in each row and column of the second-layer satellites is , and the maximum number of satellites in the second-layer satellite array is:

[0091] ;

[0092] Under the condition that the ground resolution of the satellite array remains unchanged, the two-layer staggered layout can increase the number of satellites and further improve the total energy and signal-to-noise ratio of the laser echo signal. In addition to its unique "simultaneous transmission and reception, multiple transmissions and multiple receptions" cooperative working mechanism, array-type field stop 4 design, and satellite placement architecture, the spaceborne lidar system also completely includes the key components necessary to realize the lidar function, and they work together to ensure the effective transmission, reception, and processing of laser pulse signals. As Figure 7 shown, each independent lidar device in the array mainly consists of a laser emission unit 1, a transmission control unit 2, a telescope 3, an array-type field stop 4, and a detection and acquisition unit 5.

[0093] The laser emission unit 1 includes a laser, a beam shaper, and a transmission optical system, etc., which are used to generate and adjust the characteristics of laser pulses, such as wavelength, pulse width, and repetition frequency, etc., and are responsible for emitting high-intensity pulsed lasers to the Earth's surface. These laser pulses are precisely time-controlled and energy-calibrated to ensure that the lasers emitted by all satellites under the synchronization mechanism can be precisely superimposed, thereby enhancing the total emission energy.

[0094] The emission control unit 2 is used to control the laser emission units 1 in the array to synchronously emit laser pulses. This unit adopts a time synchronization mechanism. Through two-way communication between satellites and combining with the satellite operation status, it dynamically corrects the time difference between satellites and controls the laser emission units 1 on each satellite to ensure that they emit ( a) laser pulse at the same moment or within a very short time (sub-nanosecond level), achieving the synchronous emission of laser pulses, forming a powerful laser pulse array, forming ( a) light spot in the ocean, and realizing the effective superposition of laser energy.

[0095] The telescope 3 is responsible for collecting laser echoes. This unit usually has a large aperture and high sensitivity, and also includes a pointing control system to ensure that the telescope can accurately align with the target area, responsible for collecting the laser echo signals reflected from the Earth's surface and inputting them to the array-type field stop 4. The array-type field stop 4 is responsible for matching and separating the echoes.

[0096] The detection and acquisition unit 5 includes a spectral filter, a photodetector (such as an avalanche photodiode or a silicon photomultiplier), and a signal amplifier, etc. The detection and acquisition unit 5 is responsible for converting the optical signal into an electrical signal and performing precise amplification, filtering, and digitization processing. Finally, the processed echo signal data is safely stored in the storage medium.

[0097] These components work together to collect the echo optical signals passing through the telescope and the array-type field stop 4 and convert them into strong enough electrical signals for subsequent analysis.

[0098] To ensure the stable operation and long-term reliability of the radar system, the radar system also adopts a redundant design and a fault detection mechanism. Even if some satellites break down, it will not affect the overall operation of the entire array, ensuring the stable operation and long-term reliability of the lidar satellite array system. In the case of a satellite failure, compared with the traditional single-transmitter and single-receiver system, this radar system can be flexibly adjusted to ensure that even if a certain number of satellites are lost, the laser intensity emitted by it can still reach times that of the single-transmitter and single-receiver system, and at the same time, the energy of the received echo signal is correspondingly enhanced to times that of the single-transmitter and single-receiver system, and the signal-to-noise ratio is increased to times that of the single-transmitter and single-receiver system. This design idea ensures that even in the case of some satellites or components encountering failures, the radar system can automatically adjust its configuration and quickly adapt to the new working environment, thus maintaining the continuity of the detection task and the stability of the data quality.

[0099] It should be noted that although these components are also used in the prior art, the way they work together in the present invention is completely new. Through the unique array-type field-of-view diaphragm 4 design, the signal receiving system of each lidar not only receives the echo signal of the pulsed laser it emits, but also accurately receives the echo signals of other lidars in the lidar satellite array that works in cooperation. In particular, compared with the ordinary multi-satellite array composed of satellites, the satellites in the satellite array of the present invention work together and can increase the received signal energy by times, and the signal-to-noise ratio is increased by times, thus demonstrating a more excellent detection performance.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Array-type spaceborne lidar measurement method in a multiple transmit and receive mode, characterized in that, Including the design The array pattern of the sub-satellite light spots of the satellite in the ocean, design an array-type field stop, and the aperture holes on the array-type field stop correspond to the positions of the light spots under each satellite; install the array-type field stop at the receiving end of each spaceborne lidar, lift the satellite into the air and form an array pattern of sub-satellite light spots; make each lidar synchronously emit laser signals, and each lidar synchronously receives the echo signals of the spaceborne lidars through their respective field stops.

2. The method for measuring an array-type spaceborne lidar in a multiple-transmission and multiple-reception mode according to claim 1, wherein The array pattern of the sub-satellite spot includes lidar satellites, and each lidar is equipped with a field stop with aperture holes. The lidar satellites adopt a time synchronization mechanism, and dynamically adjust the time synchronization parameters by establishing an inter-satellite high-speed communication link to correct the time difference between satellites.

3. The method for measuring an array spaceborne lidar in a multiple transmit and receive mode according to claim 2, wherein All satellites are deployed in the same orbital plane and distributed circumferentially along the orbit, and the actual operating spacing between satellites is not less than the minimum safe distance of the satellites. , the number of satellite-borne lidar satellites maximum value is determined by the ground resolution of the satellite array , the minimum safe distance of the satellites , the satellite orbital altitude and the Earth's radius .

4. The method for measuring an array spaceborne lidar in a multiple transmit and receive mode according to claim 3, characterized in that The minimum spacing of the sub-satellite point spot of each satellite in the ocean is as follows: ； According to the range of the sub-satellite spot arrays of the satellite array in the ocean, the number of satellites covering the range of the sub-satellite spot arrays is .

5. The array spaceborne lidar measurement method in the multiple transmit and receive mode according to claim 4, wherein, Calculate the maximum number of satellites per row based on the length and width and the maximum number of satellites per column to obtain : 。 6. The method for measuring an array spaceborne lidar in a multiple transmit and receive mode according to claim 5, characterized in that, Minimum pitch of the diaphragm holes on the array field stop is as follows: ； In the formula, is the focal length of the telescope of the satellite receiving unit.

7. The method for measuring an array spaceborne lidar in a multiple transmit and receive mode according to claim 6, characterized in that, The diameter of the aperture on the array field stop is : ； Wherein, is the sub-satellite spot diameter.

8. The method for measuring an array spaceborne lidar in a multiple-transmitter and multiple-receiver mode according to claim 7, wherein The array of the sub-satellite spot array patterns is the first-layer satellite array. A second-layer satellite array is constructed above the first-layer satellite array, and the sub-satellite spot array of the second-layer satellite array is within the sub-satellite spot array of the first-layer satellite array.

9. The method for measuring an array spaceborne lidar in a multiple transmit and multiple receive mode according to claim 8, wherein When the sub-satellite spot array of the satellite array is rectangular in the ocean, calculate the of the first layer of satellite array according to the length and width 。 10. The method for measuring an array spaceborne lidar in a multiple-transmitter and multiple-receiver mode according to claim 9, wherein The number of spaceborne lidar satellites in the second-layer satellite array The maximum value of : ； The maximum total number of satellites in the two-layer interleaved satellite array is: 。

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