Ocean observation method and system of small satellite agile formation using synthetic aperture altimeter

Abstract

The present application relates to a method and system for ocean observation by agile formation of small satellites with synthetic aperture altimeters, and belongs to the field of ocean remote sensing satellite observation technology. The method includes: designing multiple small satellites with synthetic aperture altimeters into the same working orbit, and the orbit is designed as a working orbit and a calibration orbit; each satellite is equipped with a Ku / Ka dual-frequency synthetic aperture altimeter; the ocean observation data collected by each satellite are sent to the ground station respectively, and the ground station processes the acquired ocean observation data respectively, and obtains the corresponding sea surface height, effective wave height, and sea surface wind field observation result data; multi-satellite data fusion processing: the observation result data is then subjected to differential processing, and finally a high-precision relative height measurement result of a wide swath of the sea surface is obtained. The present invention solves the problem of realizing remote sensing detection of wide swaths of the ocean and semi-mesoscale to sub-mesoscale ocean dynamic height under the premise of low cost and low risk.

Description

Technical Field

[0001] The present application relates to the field of ocean remote sensing satellite observation technology, and in particular to a method and system for ocean observation using a synthetic aperture altimeter small satellite agile formation. Background Art

[0002] At present, under the global background of increasingly frequent human marine activities, rapid development of space technology and rapid progress of information technology, the field of marine satellites is in a critical period of profound changes, and the development of satellite remote sensing technology is gradually shifting from focusing on the advancement of payload indicators to pursuing the effectiveness of solving scientific problems. Facing the urgent needs of current marine science, the world's marine powers are planning to develop new marine high-resolution remote sensing technologies represented by high-resolution dynamic observations to achieve remote sensing detection goals in all sea areas, all weather conditions and with high temporal and spatial resolution.

[0003] After more than 40 years of development, ocean radar altimeters, which are used for remote sensing observation of ocean dynamic processes, have now gone through three generations. The first generation is the traditional bottom-looking radar altimeter represented by Jason3 / HY2 satellites, which uses a pulse finite system to achieve high-precision measurement of sea surface height; the second generation is the bottom-looking synthetic aperture radar altimeter represented by Sentinel 3 / 6 satellites. On the basis of the first generation, it uses along-track synthetic aperture technology to increase the effective number of views within the beam, thereby achieving the purpose of suppressing sea surface speckle noise and further improving the height measurement accuracy; the third generation is the side-looking interferometric imaging radar altimeter represented by SWOT satellites, which uses synthetic aperture technology along the track and interferometric measurement technology across the track, which not only further improves the height measurement accuracy, but also effectively increases the observation width to more than 100 kilometers.

[0004] However, the first and second generation radar altimeters can only sample the sea surface along-track, with a cross-track swath of only a few kilometers, and do not have wide swath and sub-mesoscale observation capabilities. Although the third generation radar altimeter has wide swath and sub-mesoscale observation capabilities, the interferometric measurement technology system is more complex, with more error sources, and the error correction and engineering development risks are greater and the cost is higher.

[0005] Therefore, how to achieve wide-swath and sub-mesoscale observations of the ocean at low cost and low risk is a technical problem that urgently needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide a synthetic aperture altimeter small satellite agile formation ocean observation method and system to make up for the deficiencies of the prior art.

[0007] In order to achieve the above object, the specific technical solution adopted by the present invention is:

[0008] A synthetic aperture altimeter small satellite agile formation ocean observation method, the method comprising the following steps:

[0009] (1) Design satellite orbits: Design multiple synthetic aperture altimeter small satellites to have the same working orbit, which is divided into two types: working orbit and calibration orbit. Adjust the flight time interval between adjacent satellites in orbit to achieve agile variable-resolution observation of the same area.

[0010] (2) Satellite function design: Each satellite is equipped with a Ku / Ka dual-frequency synthetic aperture altimeter, which transmits Ku-band and Ka-band electromagnetic waves, receives and collects the echo signals reflected by the sea surface after the Ku-band and Ka-band electromagnetic waves are transmitted through the atmosphere, so as to obtain ocean observation data;

[0011] (3) Data acquisition by the ground station: The ocean observation data collected by each satellite is sent to the ground station separately. The ground station processes the acquired ocean observation data and obtains the corresponding sea surface height, significant wave height, and sea surface wind field observation result data;

[0012] (4) Multi-satellite data fusion processing: In step (3), the observation data of each satellite is obtained, and the observation values ​​of adjacent satellites at the same latitude are differentially processed to finally obtain a high-precision relative height measurement result for a wide swath of the sea surface.

[0013] Furthermore, in the step (1), considering the requirements of ocean sub-mesoscale calibration and authenticity verification, the satellite orbit is designed to cover the designated areas of the Pacific Ocean, Atlantic Ocean and Indian Ocean; the number of the multiple synthetic aperture altimeter small satellites is 10, but the specific number is not limited thereto as long as the technical purpose of the present invention can be achieved; the working orbit is a sun-synchronous orbit with an orbital altitude of 550-600km; the design can adjust the flight time intervals between the multiple synthetic aperture altimeter small satellites to obtain more comprehensive ocean observation data.

[0014] Furthermore, in step (2), the Ku / Ka dual-frequency synthetic aperture altimeter adopts an along-track synthetic aperture system and dual-frequency fusion technology, transmits Ku-band and Ka-band electromagnetic waves through an antenna, receives and collects echo signals of the Ku-band and Ka-band electromagnetic waves reflected by the sea surface after being transmitted through the atmosphere, so as to obtain sea surface height observation data; the antenna is a Ku / Ka dual-frequency common-aperture flat-panel antenna.

[0015] Furthermore, the Ku / Ka dual-frequency synthetic aperture altimeter includes an antenna subunit and an electronic device subunit; the antenna subunit is a Ku / Ka dual-frequency common aperture flat panel antenna, located at the satellite body facing the ground

[0016] , whose function is to amplify the frequency synthesis excitation signal and then radiate the microwave signal in the specified direction, then receive the echo signal from the ground or the target, amplify the echo signal and send it to the receiver for processing; the electronic equipment subunit includes a solid-state power amplifier unit, a microwave front-end unit, a receiving unit, a numerical control acquisition unit, a frequency synthesis and waveform generation unit, the output of the solid-state power amplifier unit is the input of the microwave front-end unit, the output of the microwave front-end unit is the input of the receiving unit, the output of the frequency synthesis synthesizer and waveform generation unit is the input of the solid-state power amplifier unit, and the output of the receiving unit is the input of the numerical control acquisition unit.

[0017] In addition, the solid-state power amplifier unit includes two single machines, a Ka-band power amplifier and a Ku-band power amplifier, and adopts a pulse solid-state power amplifier; the microwave front-end unit includes a Ka-band microwave front-end and a Ku-band microwave front-end, and the entire microwave front-end is controlled by instructions to realize transmission, reception and internal calibration switch control; the frequency synthesizer and waveform generating unit generates two C-band intermediate frequency transmission signals, which are transmitted to the solid-state power amplifier unit as excitation signals after up-conversion to the Ka / Ku band, and at the same time generate a C-band de-skewed local oscillator signal as a reference signal for receiving echoes; the receiving unit receives Ka-band and Ku-band to generate intermediate frequency echo signals; the numerical control acquisition unit completes the processing of the intermediate frequency echo signals, obtains the information of the flight orbit and attitude through the satellite bus, and collects and sends the telemetry data of each channel, and at the same time sends the generated observation data to the satellite data transmission subsystem.

[0018] A synthetic aperture altimeter small satellite agile formation ocean observation system, which is used for the synthetic aperture altimeter small satellite agile formation ocean observation method, specifically comprising:

[0019] A plurality of satellites, satellite orbits are designed based on the plurality of satellites, and each satellite performs sea surface height observation by carrying a Ku / Ka dual-frequency synthetic aperture altimeter to obtain sea surface height observation data;

[0020] The satellite transmits the received ocean observation data to the ground station, and the ground station processes the ocean observation data to obtain corresponding observation results of sea surface height, significant wave height, and sea surface wind field;

[0021] The ground station processes the sea surface height observation results of each satellite, and further performs differential processing to obtain high-precision relative height measurement results of the sea surface wide swath.

[0022] Advantages and beneficial effects of the present invention:

[0023] The present invention adopts the Ku / Ka dual-frequency synthetic aperture altimeter and the agile formation system of small satellites to realize semi-mesoscale to sub-mesoscale ocean dynamic altitude observation with low observation cost and low risk; by controlling the flight time interval between satellites, agile variable-resolution observation of the same area can be achieved, providing a flexible and efficient observation means for studying ocean phenomena at multiple temporal and spatial scales.

[0024] The main features of the satellite payload in the present invention are: adopting Ku+Ka ​​dual frequency bands; adopting Ku / Ka common aperture flat antenna; adopting Ku / Ka dual frequency fusion, and the Ku / Ka dual frequency synthetic aperture altimeter has the technical features of extremely low ranging noise floor and Ku / Ka dual frequency data fusion.

[0025] The present invention solves the problem of realizing wide-swath and sub-mesoscale observation of the ocean under the premise of low cost and low risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a synthetic aperture altimeter agile formation provided in an embodiment of the present application.

[0027] Figure 2 This is a block diagram of the payload composition of the Ku / Ka dual-frequency synthetic aperture altimeter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0029] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0030] The following specifically describes the above-mentioned synthetic aperture altimeter small satellite agile formation ocean observation method and system in combination with satellite orbit design, each satellite's functional design, and data processing. Example 1: Inversion of echo signal at entry distance.

[0031] Example 1: Satellite orbit design

[0032] In this embodiment, 10 satellites are selected, and their orbits are designed to be two types: working orbits and calibration orbits.

[0033] The working orbit has an altitude of 550-600km, an orbital inclination of 90°-100°, a return period of 27 days for the satellites in the working orbit, and 404 orbits per cycle. The calibration orbit has an altitude of 550-570km, an orbital inclination of 95°-100°, a return period of 1 day for the 10 satellites in the calibration orbit, and 15 orbits per cycle. All 10 satellites operate in a sun-synchronous orbit with the same orbital parameters. The local time of the descending node is nominally 6:30 (AM), so that after the first satellite observes an area on the ocean, the second satellite can fly over the area after a certain time interval to complete the observation of the same area. The third to tenth satellites fly over and observe in turn at the same time interval. The typical time interval between adjacent satellites is 21.5 seconds, corresponding to a sub-satellite point track interval of 10km at the equator (i.e., the cross-orbit sampling rate). Under the condition of maintaining a relatively stable orbital phase relationship, the 10 satellites can form an observation swath of 100km (with an extrapolation of 5km at the beginning and end).

[0034] In the satellite orbit design, the needs of ocean sub-mesoscale calibration and authenticity verification are taken into consideration, and the satellite orbit is designed to cover designated areas of the Pacific Ocean, Atlantic Ocean and Indian Ocean. In actual observations, the flight time interval between adjacent satellites can be adjusted in orbit, so as to achieve agile variable-resolution observations in the same area.

[0035] Analyze the track design:

[0036] Designed orbit: Sun-synchronous regression orbit, the descending node local time is 6:30, the regression period is 27 days, and the number of regression circles is 404.

[0037] According to the orbit design requirements, the 100km width of the constellation needs to cover designated coordinate points to complete tasks such as ocean observation and calibration verification. The designated coordinate points are as follows:

[0038] Table 1 Observation coordinate points

[0039] .

[0040] Taking the 27-day regression cycle as an example, we conduct a fixed-point analysis (i.e., a point where the sea level and sea surface temperature do not change):

[0041] During the 27-day revisit period, each coordinate point can be covered and observed twice (once for ascending orbit and once for descending orbit). The following analysis is conducted on the five points P1, P2, P3, A1, and SWOT_cal.

[0042] When P1 was first covered and observed, it fell between the tracks of the third and fourth satellites, closer to the fourth satellite. When P1 was covered for the second time, it was located on the track of the fifth satellite.

[0043] When point P2 is covered and observed for the first time, point P2 is on the track of the 6th satellite, that is, it can be directly observed by the 6th satellite. When point P2 is covered for the second time, it falls between the tracks of the 8th and 9th satellites, and is closer to the position of the 9th satellite.

[0044] When point P3 is covered and observed for the first time, point P3 is between the 5th and 6th satellites. When point P3 is covered and observed for the second time, point P3 is between the 5th and 6th satellites.

[0045] When point A1 was covered for the first time, it was between the 8th and 9th satellites, closer to the track of the 9th satellite. When point A1 was covered for the second time, it was between the 5th and 6th satellites, closer to the track of the 5th satellite.

[0046] Example 2: Satellite Function Design

[0047] In this embodiment, each satellite is equipped with a Ku / Ka dual-frequency synthetic aperture altimeter to observe the sea surface height during the operation of the working orbit. During observation, the Ku / Ka dual-frequency synthetic aperture altimeter transmits Ku-band and Ka-band electromagnetic waves through the antenna, and receives and collects the echo signals of the Ku-band and Ka-band electromagnetic waves reflected by the sea surface after being transmitted through the atmosphere through the antenna (Ku / Ka dual-frequency common-aperture flat antenna) to obtain sea surface height observation data.

[0048] 10 satellites are in agile formation on the same orbital plane. The typical flight time interval between adjacent satellites is 21.5 seconds. Each satellite is equipped with the same Ku / Ka dual-frequency synthetic aperture altimeter payload. The simultaneous operation of 10 satellites requires consideration of inter-satellite isolation. This embodiment adopts polarization and code division isolation. The antennas between adjacent satellites use different linear polarizations and transmit orthogonal coded waveforms at the same time.

[0049] like Figure 2 As shown, the main payload of the first satellite 1 is a Ku / Ka dual-frequency synthetic aperture altimeter, and the auxiliary payloads include a data transmission payload, a high-sensitivity navigation receiving payload, a laser angle reflector, etc. The satellite platform provides the required power for the Ku / Ka dual-frequency synthetic aperture altimeter and provides it with a suitable temperature environment to ensure that it works in the best working state.

[0050] The following is a detailed description of the main payload Ku / Ka dual-frequency synthetic aperture altimeter:

[0051] In this embodiment, the Ku / Ka dual-frequency synthetic aperture altimeter has the technical characteristics of extremely low ranging noise floor and Ku / Ka dual-frequency data fusion, and has certain international advancement. The main payload Ku / Ka dual-frequency synthetic aperture altimeter specifically includes an antenna subunit and an electronic equipment subunit.

[0052] (1) Antenna subunit

[0053] The purpose of the antenna subunit is to amplify the frequency synthesis excitation signal and radiate the microwave signal in the specified direction, then receive the echo signal from the ground or the target, amplify the echo signal and send it to the receiver for processing.

[0054] The antenna subunit includes a Ku / Ka dual-frequency co-aperture flat panel antenna, which is located on the ground facing the satellite body. In this embodiment, the Ku-band antenna has an aperture of 819.2 mm and a beam width of 1.55 degrees, and the Ka-band antenna has an aperture of 614.4 mm and a beam width of 0.77 degrees. The Ku / Ka dual-frequency co-aperture flat panel antenna includes a radiation layer, a Ku power layer and a Ka power layer, with a total thickness of 2.5 cm.

[0055] (2) Electronic equipment subunit

[0056] The electronic equipment subunit includes a solid-state power amplifier unit, a microwave front-end unit, a receiving unit, a digital control acquisition unit, a frequency synthesizer and a waveform generating unit.

[0057] Solid-state power amplifier unit: This unit includes two single units: Ka-band power amplifier and Ku-band power amplifier, and adopts pulse solid-state power amplifier.

[0058] Microwave front-end unit: The module includes Ka-band microwave front-end and Ku-band microwave front-end, which are respectively composed of circulator, microwave electronic switch, attenuator, directional coupler and other circuits. The entire microwave front-end is controlled by instructions to realize transmission, reception and internal calibration switch control.

[0059] Frequency synthesizer and waveform generation unit: This unit includes frequency multiplication components, direct digital chirp signal synthesizer (DDS) components, transmission frequency conversion components and local oscillator frequency conversion components. Under the triggering of the control signal, the chirp signal generated by the DDS is processed by frequency multiplication and frequency conversion to generate two C-band intermediate frequency transmission signals, which are up-converted to the Ka / Ku band and transmitted to the solid-state power amplifier unit as an excitation signal. The unit also generates a C-band de-skewed local oscillator signal as a reference signal for receiving radar echoes.

[0060] Receiving unit: This unit includes two down-conversion channels and two C-band receiver channels. The down-conversion channel down-converts the Ka / Ku-band echo signal received by the antenna to the C-band and then transmits it to the C-band receiver channel. The C-band receiver channel includes components such as low-noise amplifier, de-slope mixer, and intermediate frequency amplifier. The generated intermediate frequency signal is quantized by the acquisition channel designed by the payload control and signal processor.

[0061] Digital control acquisition unit: This unit completes the functions of medium frequency echo signal acquisition, quantification, fast Fourier transform (FFT), model tracking processing, timing control, etc., and completes the communication with the satellite computer, that is, obtaining flight attitude information (including time code, attitude data, etc.) through the satellite bus, and collects and sends telemetry data of each channel. At the same time, the scientific data generated by the altimeter is sent to the satellite data transmission subsystem through high-speed serial mode.

[0062] The electronic equipment subunit may also include a radio frequency front end: in the transmitting path, the unit up-converts the C-band transmitting signal transmitted from the cabin to the Ka / Ku band, and transmits it to the solid-state power amplifier as an excitation signal; in the receiving path, the radio frequency front end down-converts the Ka / Ku band echo signal received by the antenna to the C band, and transmits it to the de-skewed receiver of the receiving unit; the functions of the radio frequency front end may also be integrated into the frequency synthesizer and the waveform generating unit, that is, the unit does not need to be set up separately.

[0063] In summary, the Ku / Ka dual-frequency synthetic aperture altimeter carried by each satellite adopts the along-track synthetic aperture system and dual-frequency fusion technology; the main features of the satellite payload are: (1) adopting the Ku+Ka ​​dual-frequency band; (2) adopting the Ku / Ka common-aperture flat-panel antenna; and (3) adopting the Ku / Ka dual-frequency fusion.

[0064] Embodiment 3:

[0065] like Figure 1 As shown, based on Embodiments 1 and 2, this embodiment provides a method for agile formation ocean observation of small satellites using a synthetic aperture altimeter, specifically an ocean observation method using a dual satellite companion flight of an interferometric imaging altimeter and a lidar, including the following steps:

[0066] (1) Designing satellite orbits: multiple synthetic aperture altimeter small satellites are designed to have the same working orbit, and the orbits are designed to have two types: working orbit and calibration orbit. The flight time interval between adjacent satellites is adjusted on-orbit to achieve agile variable-resolution observation of the same area. Considering the requirements of ocean sub-mesoscale calibration and authenticity verification, the satellite orbits are designed to cover designated areas of the Pacific, Atlantic and Indian Oceans. The number of the multiple synthetic aperture altimeter small satellites is 10, but the specific number is not limited to this, as long as the technical purpose of the present invention can be achieved. The working orbit is a sun-synchronous orbit with an orbital altitude of 550-600 km. The design can adjust the flight time interval between the multiple synthetic aperture altimeter small satellites to obtain more comprehensive ocean observation data.

[0067] (2) Satellite function design: as shown in Example 2, each satellite is equipped with a Ku / Ka dual-frequency synthetic aperture altimeter, which transmits Ku-band and Ka-band electromagnetic waves, receives and collects echo signals reflected by the sea surface after the Ku-band and Ka-band electromagnetic waves are transmitted through the atmosphere, so as to obtain ocean observation data;

[0068] (3) Data acquisition by the ground station: The ocean observation data collected by each satellite is sent to the ground station separately. The ground station processes the acquired ocean observation data and obtains the corresponding sea surface height, significant wave height, and sea surface wind field observation result data;

[0069] (4) Multi-satellite data fusion processing: Step (3) obtains the observation result data of each satellite, and then performs differential processing to finally obtain a high-precision relative height measurement result for a wide swath of the sea surface.

[0070] The synthetic aperture altimeter small satellite agile formation ocean observation method provided by the present invention adopts Ku / Ka dual-frequency synthetic aperture altimeter and small satellite agile formation system to realize semi-mesoscale to sub-mesoscale ocean dynamic altitude observation, and the observation cost is low and the risk is low. At the same time, the above synthetic aperture altimeter small satellite agile formation ocean observation method can realize agile variable resolution observation in the same area by controlling the flight time interval between satellites, providing a flexible and efficient observation means for studying ocean phenomena at multiple temporal and spatial scales.

[0071] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A synthetic aperture altimeter small satellite agile formation ocean observation method, characterized in that: The method comprises the following steps: (1) Design satellite orbits: Design multiple synthetic aperture altimeter small satellites to have the same working orbit, which is divided into two types: working orbit and calibration orbit. Adjust the flight time interval between adjacent satellites in orbit to achieve agile variable-resolution observation of the same area. (2) Satellite function design: Each satellite is equipped with a Ku / Ka dual-frequency synthetic aperture altimeter, which transmits Ku-band and Ka-band electromagnetic waves, receives and collects the echo signals reflected by the sea surface after the Ku-band and Ka-band electromagnetic waves are transmitted through the atmosphere, so as to obtain ocean observation data; (3) Data acquisition by the ground station: The ocean observation data collected by each satellite is sent to the ground station separately. The ground station processes the acquired ocean observation data and obtains the corresponding sea surface height, significant wave height, and sea surface wind field observation result data; (4) Multi-satellite data fusion processing: Step (3) obtains the observation result data of each satellite, and then performs differential processing to finally obtain a high-precision relative height measurement result for a wide swath of the sea surface.

2. The method for ocean observation using a small satellite agile formation using a synthetic aperture altimeter according to claim 1, characterized in that: In step (1), based on the ocean observation requirements and taking into account the requirements for the observation and calibration of the sea level and sea surface temperature constant point, the satellite orbit is designed to cover the designated areas of the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean.

3. The synthetic aperture altimeter small satellite agile formation ocean observation method according to claim 1, characterized in that: The working orbit is a sun-synchronous orbit with an orbital altitude of 550-600km.

4. The method for ocean observation using a small satellite agile formation using a synthetic aperture altimeter according to claim 1, wherein: In the step (2), the Ku / Ka dual-frequency synthetic aperture altimeter adopts an along-track synthetic aperture system and dual-frequency fusion technology, transmits Ku-band and Ka-band electromagnetic waves through an antenna, receives and collects echo signals of the Ku-band and Ka-band electromagnetic waves reflected by the sea surface after being transmitted through the atmosphere, so as to obtain sea surface height observation data; the antenna is a Ku / Ka dual-frequency common-aperture flat-panel antenna.

5. The method for ocean observation using agile formation of small satellites using synthetic aperture altimeters according to claim 1, characterized in that: The Ku / Ka dual-frequency synthetic aperture altimeter includes an antenna subunit and an electronic equipment subunit; the antenna subunit is a Ku / Ka dual-frequency common-aperture flat-panel antenna, located on the ground facing the satellite body, and its function is to amplify the frequency synthesis excitation signal and radiate the microwave signal in a specified direction, and then receive the echo signal from the ground or the target, amplify the echo signal and send it to the receiver for processing; the electronic equipment subunit includes a solid-state power amplifier unit, a microwave front-end unit, a receiving unit, a numerical control acquisition unit, a frequency synthesis synthesizer and a waveform generating unit; the output of the solid-state power amplifier unit is the input of the microwave front-end unit, the output of the microwave front-end unit is the input of the receiving unit, the output of the frequency synthesis synthesizer and the waveform generating unit is the input of the solid-state power amplifier unit, and the output of the receiving unit is the input of the numerical control acquisition unit.

6. The method for ocean observation using agile formation of small satellites using synthetic aperture altimeters according to claim 5, characterized in that: The solid-state power amplifier unit includes two single machines, a Ka-band power amplifier and a Ku-band power amplifier, and adopts a pulse solid-state power amplifier; the microwave front-end unit includes a Ka-band microwave front-end and a Ku-band microwave front-end, and the entire microwave front-end is controlled by instructions to realize transmission, reception and internal calibration switch control; the frequency synthesizer and waveform generating unit generates two C-band intermediate frequency transmission signals, which are transmitted to the solid-state power amplifier unit as excitation signals after up-conversion to the Ka / Ku band, and at the same time generate a C-band de-skewed local oscillator signal as a reference signal for receiving echoes; the receiving unit receives Ka-band and Ku-band to generate intermediate frequency echo signals; the numerical control acquisition unit completes the processing of the intermediate frequency echo signals, obtains the information of the flight orbit and attitude through the satellite bus, and collects and sends the telemetry data of each channel, and at the same time sends the generated observation data to the satellite data transmission subsystem.

7. A synthetic aperture altimeter small satellite agile formation ocean observation system, characterized in that: The system is used for the synthetic aperture altimeter small satellite agile formation ocean observation method described in claim 1, and the observation system comprises: A plurality of satellites, satellite orbits are designed based on the plurality of satellites, each satellite performs sea surface height observation by carrying a Ku / Ka dual-frequency synthetic aperture altimeter to obtain sea surface height observation data; The satellite transmits the received ocean observation data to the ground station, and the ground station processes the ocean observation data to obtain corresponding observation results of sea surface height, significant wave height, and sea surface wind field; The ground station processes the sea surface height observation results of each star, and then performs differential processing to obtain a high-precision relative height measurement result of a wide swath of the sea surface.

Images