Spaceborne Interferometric Imaging Altimeter Echo Simulator

Abstract

The spaceborne interferometric imaging altimeter echo simulator provided by this application relates to the fields of interferometric imaging and radar echo simulation technology. It includes a radio frequency subsystem, an intermediate frequency subsystem, and a sea surface echo calculation subsystem. Among them, the radio frequency subsystem is used to convert a radio frequency transmitted analog signal into an intermediate frequency transmitted analog signal, and convert an intermediate frequency echo analog signal into a radio frequency echo analog signal; the intermediate frequency subsystem is used to convert an intermediate frequency transmitted analog signal into an intermediate frequency transmitted digital signal, and convert an intermediate frequency echo digital signal into an intermediate frequency echo analog signal; the sea surface echo calculation subsystem is used to receive an intermediate frequency transmitted data packet and generate, according to user settings, intermediate frequency echo data packets corresponding to the sea surface imaging areas of two antennas at each pulse moment. This spaceborne interferometric imaging altimeter echo simulator can effectively test functions such as on-orbit altitude tracking, on-orbit automatic gain adjustment, and on-orbit real-time interferometric imaging of the spaceborne interferometric imaging altimeter, and has strong applicability.

Description

Technical Field

[0001] This application belongs to the technical field of interference imaging and radar echo simulation, and specifically relates to a spaceborne interferometric imaging altimeter echo simulator. Background Art

[0002] Spaceborne interferometric imaging altimeters can accurately measure the heights of wide-swath sea surfaces and land surface water bodies (large rivers and lakes) through dual-channel interference technology. Since the observation scenes of spaceborne interferometric imaging altimeters for the ocean and land are relatively rich, the echo signals under different observation scenes are also different. The processing of echo signals by spaceborne interferometric imaging altimeters under different scenes is also different. During the development of the payload of a spaceborne interferometric imaging altimeter, the development of functions such as on-orbit automatic gain adjustment, on-orbit altitude tracking, and on-orbit real-time interference imaging is involved, and these functions need to be fully verified on the ground before being put into use. In addition, the most important dual-channel interference performance of a spaceborne interferometric imaging altimeter also needs to be fully tested on the ground. Therefore, in the process of developing a spaceborne interferometric imaging altimeter, it is essential to simulate the echo signals of the spaceborne interferometric imaging altimeter under different observation scenes on the ground. Summary of the Invention

[0003] The purpose of this application is to overcome the defects existing in the prior art.

[0004] To achieve the above purpose, this application proposes a spaceborne interferometric imaging altimeter echo simulator, adopting the following technical solutions:

[0005] The spaceborne interferometric imaging altimeter echo simulator proposed in this application includes:

[0006] A radio frequency subsystem, configured to receive the first radio frequency transmission simulation signal and the second radio frequency transmission simulation signal transmitted by the spaceborne interferometric imaging altimeter, convert the first radio frequency transmission simulation signal into a first intermediate frequency transmission simulation signal, convert the second radio frequency transmission simulation signal into a second intermediate frequency transmission simulation signal, and transmit the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal to the intermediate frequency subsystem;

[0007] An intermediate frequency subsystem, configured to receive the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal transmitted by the radio frequency subsystem, convert the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal into digital signals respectively, generate a first intermediate frequency transmission digital signal and a second intermediate frequency transmission digital signal, and packetize the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to generate an intermediate frequency transmission data packet;

[0008] The sea surface echo calculation subsystem is used to generate the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal corresponding to the sea surface imaging area at each pulse moment of two antennas based on the intermediate frequency transmission data packet transmitted by the intermediate frequency subsystem and according to the user settings, store the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, and packetize the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal to generate an intermediate frequency echo data packet;

[0009] The intermediate frequency subsystem is further configured to receive the intermediate frequency echo data packet transmitted by the sea surface echo calculation subsystem under the control of the timing pulse signal output by the spaceborne interferometric imaging altimeter, unpack the intermediate frequency echo data packet into the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, convert the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal into analog signals respectively to generate a first intermediate frequency echo analog signal and a second intermediate frequency echo analog signal, wherein there is a set phase difference between the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal;

[0010] The radio frequency subsystem is further configured to receive the first intermediate frequency echo analog signal and the second intermediate frequency echo analog signal transmitted by the intermediate frequency subsystem, convert the first intermediate frequency echo analog signal into a third radio frequency echo analog signal and a fourth radio frequency echo analog signal, convert the second intermediate frequency echo analog signal into a fifth radio frequency echo analog signal and a sixth radio frequency echo analog signal, and transmit the third radio frequency echo analog signal, the fourth radio frequency echo analog signal, the fifth radio frequency echo analog signal and the sixth radio frequency echo analog signal to the spaceborne interferometric imaging altimeter.

[0011] In some examples, the radio frequency subsystem includes an attenuation component, and the attenuation component includes a first attenuator and a second attenuator, wherein:

[0012] The first attenuator is configured to receive the first radio frequency transmission analog signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the first radio frequency transmission analog signal from a preset first threshold to a preset second threshold to obtain a third radio frequency transmission analog signal;

[0013] The second attenuator is configured to receive the second radio frequency transmission analog signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the second radio frequency transmission analog signal from the first threshold to the second threshold to obtain a fourth radio frequency transmission analog signal.

[0014] In some examples, the radio frequency subsystem further includes a down-conversion component, and the down-conversion component includes a first down-converter and a second down-converter, wherein:

[0015] The first down-converter is configured to receive the third RF transmission analog signal transmitted by the first attenuator and reduce the frequency of the third RF transmission analog signal from a set third threshold to a set fourth threshold to obtain a first intermediate-frequency transmission analog signal;

[0016] The second down-converter is configured to receive the fourth RF transmission analog signal transmitted by the second attenuator and reduce the frequency of the fourth RF transmission analog signal from the third threshold to the fourth threshold to obtain a second intermediate-frequency transmission analog signal.

[0017] In some examples, the intermediate-frequency subsystem includes a first analog-to-digital converter ADC1, a second analog-to-digital converter ADC2, and a central controller, where:

[0018] The first analog-to-digital converter ADC1 is configured to receive the first intermediate-frequency transmission analog signal sent by the first down-converter, convert the first intermediate-frequency transmission analog signal into a first intermediate-frequency transmission digital signal, and then send it to the central controller;

[0019] The second analog-to-digital converter ADC2 is configured to receive the second intermediate-frequency transmission analog signal sent by the second down-converter, convert the second intermediate-frequency transmission analog signal into a second intermediate-frequency transmission digital signal, and then send it to the central controller;

[0020] The central controller is configured to receive the first intermediate-frequency transmission digital signal and the second intermediate-frequency transmission digital signal, packetize the first intermediate-frequency transmission digital signal and the second intermediate-frequency transmission digital signal to obtain the intermediate-frequency transmission data packet, and transmit the intermediate-frequency transmission data packet to the sea-surface echo calculation subsystem.

[0021] In some examples, the sea-surface echo calculation subsystem is further configured to, according to the intermediate-frequency transmission data packet and the six orbital elements, satellite attitude, payload operating mode, and sea condition information input by the user, adopt a linear superposition algorithm for echo signals to obtain the intermediate-frequency echo data corresponding to the sea-surface imaging area at each pulse moment.

[0022] In some examples, the intermediate-frequency subsystem further includes a first digital-to-analog converter DAC1 and a second digital-to-analog converter DAC2, where:

[0023] The central controller is further configured to obtain the intermediate-frequency echo data packet from the sea-surface echo calculation subsystem, unpack the intermediate-frequency echo data packet to obtain the first intermediate-frequency echo digital signal and the second intermediate-frequency echo digital signal, transmit the first intermediate-frequency echo digital signal to the first digital-to-analog converter DAC1, and transmit the second intermediate-frequency echo digital signal to the second digital-to-analog converter DAC2;

[0024] The first digital-to-analog converter DAC1 is used to convert the first intermediate-frequency echo digital signal into a first intermediate-frequency echo analog signal and transmit the first intermediate-frequency echo analog signal to the radio frequency subsystem;

[0025] The second digital-to-analog converter DAC2 is used to convert the second intermediate-frequency echo digital signal into a second intermediate-frequency echo analog signal and transmit the second intermediate-frequency echo analog signal to the radio frequency subsystem.

[0026] In some examples, the radio frequency subsystem includes an up-conversion component, and the up-conversion component includes a first up-converter and a second up-converter, where:

[0027] The first up-converter is used to receive the first intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the first intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a first radio-frequency echo analog signal;

[0028] The second up-converter is used to receive the second intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the second intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a second radio-frequency echo analog signal.

[0029] In some examples, the radio frequency subsystem further includes a power splitting component, and the power splitting component includes a first power splitter and a second power splitter, where:

[0030] The first power splitter is used to divide the first radio-frequency echo signal into a third radio-frequency echo signal and a fourth radio-frequency echo signal according to power and transmit the third radio-frequency echo signal to the first receiving channel of the spaceborne interferometric imaging altimeter;

[0031] The second power splitter is used to divide the second radio-frequency echo signal into a fifth radio-frequency echo signal and a sixth radio-frequency echo signal according to power and transmit the fifth radio-frequency echo signal to the second receiving channel of the spaceborne interferometric imaging altimeter.

[0032] In some examples, the central controller is the programmable logic hardware PL in the chip RFSoC.

[0033] Compared with the prior art, the advantages of the present application are as follows:

[0034] By pre-generating intermediate-frequency echo data through the sea surface echo calculation subsystem, the flexibility is relatively strong, the echo data in different scenarios can be simulated, the functions such as on-orbit altitude tracking, on-orbit automatic gain adjustment, and on-orbit real-time interferometric imaging of the spaceborne interferometric imaging altimeter can be effectively tested, and various working modes of the spaceborne interferometric imaging altimeter are compatible, so the applicability is relatively strong. Description of the Drawings

[0035] Figure 1 The figure shows a schematic diagram of the composition structure of the spaceborne interferometric imaging altimeter echo simulator provided by the embodiment of the present application;

[0036] Figure 2 The figure shows a schematic diagram of the internal composition structure of the programmable logic hardware PL provided by the embodiment of the present application;

[0037] Figure 3 The figure shows a schematic diagram of the working principle of the spaceborne interferometric imaging altimeter echo simulator provided by the embodiment of the present application. Specific embodiments

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] As Figure 1 shown, the spaceborne interferometric imaging altimeter echo simulator provided by the embodiment of the present application includes a radio frequency subsystem, an intermediate frequency subsystem, and a sea surface echo calculation subsystem, where:

[0040] The radio frequency subsystem is configured to receive the first radio frequency transmission analog signal and the second radio frequency transmission analog signal transmitted by the spaceborne interferometric imaging altimeter, convert the first radio frequency transmission analog signal into a first intermediate frequency transmission analog signal, convert the second radio frequency transmission analog signal into a second intermediate frequency transmission analog signal, and transmit the first intermediate frequency transmission analog signal and the second intermediate frequency transmission analog signal to the intermediate frequency subsystem.

[0041] In some examples, the radio frequency subsystem includes a frequency synthesizer, where:

[0042] The frequency synthesizer is configured to generate the working clock and local oscillator signal required by the intermediate frequency subsystem and the radio frequency subsystem based on the reference clock signal of the high-stability crystal oscillator or the synchronous clock from the interferometric imaging altimeter as a reference, and adopt the direct frequency synthesis method.

[0043] Specifically, the first downconverter downconverts the attenuated third radio frequency transmission signal with the local oscillator signal provided by the frequency synthesizer to output a first intermediate frequency transmission signal; the second downconverter downconverts the attenuated fourth radio frequency transmission signal with the local oscillator signal provided by the frequency synthesizer to output a second intermediate frequency transmission signal.

[0044] Specifically, the first upconverter upconverts the first intermediate-frequency signal output by DAC1 with the local oscillator signal provided by the frequency synthesizer to output a first radio-frequency echo signal; the second upconverter upconverts the second intermediate-frequency signal output by DAC2 with the local oscillator signal provided by the frequency synthesizer to output a second radio-frequency echo signal.

[0045] In some examples, the radio-frequency subsystem further includes an attenuation component, and the attenuation component includes a first attenuator and a second attenuator, where:

[0046] The first attenuator is configured to receive the first radio-frequency transmission analog signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the first radio-frequency transmission analog signal from a preset first threshold to a preset second threshold;

[0047] The second attenuator is configured to receive the second radio-frequency transmission analog signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the second radio-frequency transmission analog signal from the first threshold to the second threshold.

[0048] Specifically, the spaceborne interferometric imaging altimeter outputs the first radio-frequency transmission analog signal through the first transmission channel and outputs the second radio-frequency transmission analog signal through the second transmission channel. Since the power of the radio-frequency transmission analog signal output by the spaceborne interferometric imaging altimeter is relatively large, the radio-frequency transmission analog signal cannot be directly input into the radio-frequency subsystem, and it is necessary to attenuate the first radio-frequency transmission analog signal and the second radio-frequency transmission analog signal respectively in advance to obtain a third radio-frequency transmission analog signal and a fourth radio-frequency transmission analog signal.

[0049] In some examples, the radio-frequency subsystem further includes a downconversion component, and the downconversion component includes a first downconverter and a second downconverter, where:

[0050] The first downconverter is configured to receive the third radio-frequency transmission analog signal transmitted by the first attenuator and reduce the frequency of the first radio-frequency transmission analog signal from a set third threshold to a set fourth threshold to obtain a first intermediate-frequency transmission analog signal;

[0051] The second downconverter is configured to receive the fourth radio-frequency transmission analog signal transmitted by the second attenuator and reduce the frequency of the second radio-frequency transmission analog signal from the third threshold to the fourth threshold to obtain a second intermediate-frequency transmission analog signal.

[0052] Specifically, since the radio-frequency transmission signal output by the spaceborne interferometric imaging altimeter is a radio-frequency signal, while the intermediate-frequency subsystem processes intermediate-frequency signals during actual operation, it is necessary to perform downconversion processing on the radio-frequency transmission signal before it is input into the intermediate-frequency subsystem.

[0053] The intermediate frequency subsystem is mainly composed of an RFSoC. Among them, the RFSoC is an integrated chip that integrates a DAC, an ADC, a PL, etc. on the same chip.

[0054] The intermediate frequency subsystem is used to receive the first intermediate frequency transmission analog signal and the second intermediate frequency transmission analog signal transmitted by the radio frequency subsystem, convert the first intermediate frequency transmission analog signal and the second intermediate frequency transmission analog signal into digital signals respectively to generate a first intermediate frequency transmission digital signal and a second intermediate frequency transmission digital signal, and packetize the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to generate an intermediate frequency transmission data packet.

[0055] In some examples, the intermediate frequency subsystem includes a first analog-to-digital converter ADC1, a second analog-to-digital converter ADC2 and a central controller, where:

[0056] The first analog-to-digital converter ADC1 is used to receive the first intermediate frequency transmission analog signal sent by the first downconverter, convert the first intermediate frequency transmission analog signal into a first intermediate frequency transmission digital signal and then send it to the central controller;

[0057] The second analog-to-digital converter ADC2 is used to receive the second intermediate frequency transmission analog signal sent by the second downconverter, convert the second intermediate frequency transmission analog signal into a second intermediate frequency transmission digital signal and then send it to the central controller.

[0058] The central controller is used to receive the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal, packetize the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to obtain the intermediate frequency transmission data packet, and transmit the intermediate frequency transmission data packet to the sea echo calculation subsystem.

[0059] The sea echo calculation subsystem is mainly composed of an echo simulation computer and a fiber optic data transmission card.

[0060] Specifically, the echo simulation computer is a general computer.

[0061] Specifically, the fiber optic data transmission card mainly includes a programmable logic controller FPGA, a memory DDR and a PXIE interface. The fiber optic data transmission card receives the radio frequency transmission data transmitted by the intermediate frequency subsystem, and transmits the data to the hard disk of the echo simulation computer through the PXIE interface. At the same time, the fiber optic data transmission card transmits the intermediate frequency echo data in the hard disk of the echo simulation computer to the DDR through the PXIE interface for caching, and then transmits it to the intermediate frequency subsystem through the optical fiber.

[0062] The sea surface echo calculation subsystem is used to generate a first intermediate frequency echo digital signal and a second intermediate frequency echo digital signal corresponding to the sea surface imaging area of ​​the two antennas at each pulse moment based on the intermediate frequency transmission data packet transmitted by the intermediate frequency subsystem, and store the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, wherein the intermediate frequency echo data includes the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal.

[0063] In some examples, the sea surface echo calculation subsystem is also used to generate intermediate frequency echo data corresponding to the sea surface imaging area of ​​the two antennas at each pulse time using a linear superposition algorithm of echo signals based on the intermediate frequency transmission data packet and the six orbital numbers, satellite attitude, payload operating mode and sea condition information input by the user.

[0064] Specifically, the working process of the echo simulation computer is as follows:

[0065] The echo simulation computer calculates the satellite distance from the center of the earth, satellite inertial velocity, satellite beam moving velocity along the ground and satellite effective velocity at different pulse times according to the six orbit numbers and satellite attitude information input by the user. At the same time, since the sub-satellite point offline angle, satellite attitude angle, satellite hour angle, satellite orbit inclination, ascending node right ascension, perigee angle and line of sight vector geodetic latitude compensation angle are defined in different coordinate systems, a series of coordinate matrix transformations are required for the satellite-ground geometric relationship. The satellite position vector, satellite velocity vector and two antenna unit line of sight vectors at different pulse times are adjusted to simulate the actual working state of the onboard payload.

[0066] According to the sea condition information input by the user, PM spectrum and Longuet-Higgins angle spread function are used as the two-dimensional sea spectrum model. The three-dimensional sea surface is quantified, and the three-dimensional modeling of different quantization points is carried out using the linear superposition method according to different frequencies, directions and phases;

[0067] At different pulse times, the slant distances of different quantization points when illuminated by the two antenna beams are calculated, so as to calculate the echo signals of the two antennas to different quantization points, and the total echo signals of the two antennas are calculated by linear superposition method. The total echo signals of the two antennas are quantized and encoded according to the encoding method set by the protocol to obtain the intermediate frequency echo data.

[0068] Specifically, the intermediate frequency echo data is pre-generated through the sea surface echo calculation subsystem, which is highly flexible and can simulate echo data in different scenarios. It can effectively test the on-orbit altitude tracking, on-orbit automatic gain adjustment, and on-orbit real-time interferometric imaging functions of the satellite-borne interferometric imaging altimeter. It is compatible with various working modes of the satellite-borne interferometric imaging altimeter and has strong applicability.

[0069] The intermediate frequency subsystem is further configured to receive the intermediate frequency echo data packet transmitted by the sea surface echo calculation subsystem under the control of the timing pulse signal output by the spaceborne interferometric imaging altimeter, unpack the intermediate frequency echo data packet into the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, and respectively convert the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal into analog signals to generate a first intermediate frequency echo analog signal and a second intermediate frequency echo analog signal, wherein there is a set phase difference between the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal.

[0070] In some examples, the intermediate frequency subsystem further includes a first digital-to-analog converter DAC1 and a second digital-to-analog converter DAC2, wherein,

[0071] The central controller is configured to obtain the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal from the sea surface echo calculation subsystem, transmit the first intermediate frequency echo digital signal to the first digital-to-analog converter DAC1, and transmit the second intermediate frequency echo digital signal to the second digital-to-analog converter DAC2;

[0072] The first digital-to-analog converter DAC1 is configured to convert the first intermediate frequency echo digital signal into a first intermediate frequency echo analog signal and transmit the first intermediate frequency echo analog signal to the radio frequency subsystem;

[0073] The second digital-to-analog converter DAC2 is configured to convert the second intermediate frequency echo digital signal into a second intermediate frequency echo analog signal and transmit the second intermediate frequency echo analog signal to the radio frequency subsystem.

[0074] In some examples, the central controller is a programmable logic hardware PL, configured to receive the first intermediate frequency transmit digital signal and the second intermediate frequency transmit digital signal, packetize the first intermediate frequency transmit digital signal and the second intermediate frequency transmit digital signal to generate the intermediate frequency transmit data packet and transmit the intermediate frequency transmit data packet to the sea surface echo calculation subsystem.

[0075] The radio frequency subsystem is further configured to receive the first intermediate frequency echo analog signal and the second intermediate frequency echo analog signal transmitted by the intermediate frequency subsystem, convert the first intermediate frequency echo analog signal into a third radio frequency echo analog signal and a fourth radio frequency echo analog signal, convert the second intermediate frequency echo analog signal into a fifth radio frequency echo analog signal and a sixth radio frequency echo analog signal, and optionally transmit the third radio frequency echo analog signal, the fourth radio frequency echo analog signal, the fifth radio frequency echo analog signal, and the sixth radio frequency echo analog signal to the spaceborne interferometric imaging altimeter.

[0076] In some examples, the radio frequency subsystem includes an up-conversion component, and the up-conversion component includes a first up-converter and a second up-converter, where:

[0077] The first up-converter is configured to receive the first intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the first intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a first radio-frequency echo analog signal;

[0078] The second up-converter is configured to receive the second intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the second intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a second radio-frequency echo analog signal.

[0079] In some examples, the radio frequency subsystem further includes a power splitting component, and the power splitting component includes a first power splitter and a second power splitter, where:

[0080] The first power splitter is configured to divide the first radio-frequency echo signal into a third radio-frequency echo signal and a fourth radio-frequency echo signal according to power, and the third radio-frequency echo signal and the fourth radio-frequency echo signal are in phase;

[0081] The second power splitter is configured to divide the second radio-frequency echo signal into a fifth radio-frequency echo signal and a sixth radio-frequency echo signal according to power, and the fifth radio-frequency echo signal and the sixth radio-frequency echo signal are in phase.

[0082] Specifically, the third radio-frequency echo signal is transmitted to the first receiving channel of the spaceborne interferometric imaging altimeter, and the fourth radio-frequency echo signal is transmitted to the second receiving channel of the spaceborne interferometric imaging altimeter to test the phase consistency of the two receiving channels.

[0083] Specifically, the third radio-frequency echo signal is transmitted to the first receiving channel of the spaceborne interferometric imaging altimeter, and the fifth radio-frequency echo signal is transmitted to the second receiving channel of the spaceborne interferometric imaging altimeter for functions such as on-orbit altitude tracking and on-orbit interferometric imaging processing of the spaceborne interferometric imaging altimeter.

[0084] Specifically, as Figure 2 shown, the PL mainly consists of a serial interface configuration unit, an optical fiber communication interface configuration unit, a DAC interface configuration unit, an ADC interface configuration unit, a telemetry acquisition interface configuration unit, an instruction parsing unit, a timing control unit, an uplink request packet generation unit, an intermediate-frequency echo data unpacking unit, an intermediate-frequency transmission data packetizing unit, and a telemetry data packetizing unit. Where:

[0085] The serial interface configuration unit is configured to receive the working instructions sent by the ground test computer through the serial protocol and transmit the working instructions to the instruction parsing unit.

[0086] The optical fiber communication interface configuration unit is used to implement the optical fiber communication protocol and communicate with the optical fiber data transmission card through the optical fiber.

[0087] The DAC interface configuration unit is used to implement DAC configuration and transmit data to the DAC for digital-to-analog conversion.

[0088] The ADC interface configuration unit is used to implement ADC configuration and receive the data after ADC analog-to-digital conversion.

[0089] The telemetry acquisition interface configuration unit is used to acquire the intermediate frequency signal output by the radio frequency subsystem.

[0090] The instruction parsing unit parses the working instructions and generates working parameters to be transmitted to the timing control unit.

[0091] The timing control unit receives the working parameters transmitted by the instruction parsing unit, and at the same time receives the timing pulse signal sent by the numerical control unit of the spaceborne interferometric imaging altimeter, generates the working timing, and sends it to the intermediate frequency echo data generation unit, the echo request packet generation unit, and the radio frequency waveform data generation unit.

[0092] The uplink request packet generation unit receives the working timing of the timing control unit, generates an uplink request packet, and sends it to the optical fiber data transmission card through the optical fiber interface configuration unit.

[0093] The intermediate frequency echo data unpacking unit receives the intermediate frequency echo digital signal transmitted by the optical fiber data transmission card through the optical fiber interface configuration unit, and outputs the intermediate frequency echo digital signal to the DAC interface configuration unit according to the working timing generated by the timing control unit.

[0094] The intermediate frequency transmission data packet combining unit receives the two-way intermediate frequency transmission digital signals transmitted by the ADC interface configuration unit for packet combining, generates an intermediate frequency transmission data packet, sends the intermediate frequency transmission data packet to the optical fiber data transmission card through the optical fiber interface configuration unit, and further transmits the intermediate frequency transmission data packet to the sea surface echo calculation subsystem.

[0095] The telemetry data packet combining unit combines the two-way intermediate frequency echo digital signals acquired by the telemetry acquisition interface, and then sends the combined two-way intermediate frequency echo digital signals to the ground test computer through the serial interface configuration unit for verification.

[0096] As Figure 3 shown, taking the simulation of the echo data in the sea area as an example, the working principle of the spaceborne interferometric imaging altimeter echo simulator provided by this application is:

[0097] According to the operating parameters of the spaceborne interferometric imaging altimeter input by the user, as well as parameters such as the satellite platform orbit, attitude, and observation scene, and the radio frequency waveform data transmitted by the spaceborne interferometric imaging altimeter, the intermediate frequency echo data of the simulated sea surface area corresponding to the two antennas is obtained through simulation and stored in the hard disk; the fiber optic data transmission card reads the data in the hard disk and caches the intermediate frequency echo data in the DDR;

[0098] The intermediate frequency subsystem performs initialization configuration according to the operating instructions sent by the ground test computer. Then, it receives the timing pulses of the spaceborne interferometric imaging altimeter and sends an uplink request packet to the sea surface echo calculation subsystem. The sea surface echo calculation subsystem sends the combined intermediate frequency echo data to the intermediate frequency subsystem according to the uplink request packet sent by the intermediate frequency subsystem. The intermediate frequency subsystem performs digital-to-analog conversion on the intermediate frequency echo data and then outputs it to the radio frequency subsystem;

[0099] The radio frequency subsystem generates a radio frequency analog echo signal from the received intermediate frequency echo data through an up-conversion component and a power division component and inputs it into the spaceborne interferometric imaging altimeter.

[0100] Specifically, the working process of the spaceborne interferometric imaging altimeter echo simulator provided in this application is as follows:

[0101] The spaceborne interferometric imaging altimeter transmits a first radio frequency transmission analog signal and a second radio frequency transmission analog signal to the radio frequency subsystem;

[0102] The radio frequency subsystem receives the first radio frequency transmission analog signal and the second radio frequency transmission analog signal, respectively performs attenuation and down-conversion processing on the first radio frequency transmission analog signal and the second radio frequency transmission analog signal, and then obtains a first intermediate frequency transmission analog signal and a second intermediate frequency transmission analog signal and transmits the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to the intermediate frequency subsystem;

[0103] The intermediate frequency subsystem converts the first intermediate frequency signal and the second intermediate frequency signal into corresponding digital signals respectively, and then combines the two digital signals and sends them to the sea surface echo calculation subsystem;

[0104] Based on the combined digital signal, the sea surface echo calculation subsystem generates intermediate frequency echo data within a set period and stores the intermediate frequency echo data locally;

[0105] The intermediate frequency subsystem obtains a first intermediate frequency echo digital signal and a second intermediate frequency echo digital signal from the sea surface echo calculation subsystem according to the externally issued instructions, and there is a set phase difference between the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal;

[0106] The intermediate frequency subsystem converts the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal into corresponding analog signals respectively, obtains the first intermediate frequency echo analog signal and the second intermediate frequency echo analog signal, and sends the first intermediate frequency echo analog signal and the second intermediate frequency echo analog signal to the radio frequency subsystem;

[0107] The radio frequency subsystem performs up-conversion processing on the first intermediate frequency echo signal and the second intermediate frequency echo signal respectively and then inputs them into the spaceborne interferometric imaging altimeter;

[0108] Based on the first radio frequency echo analog signal and the second radio frequency echo analog signal after up-conversion processing, the spaceborne interferometric imaging altimeter generates corresponding images, completing the entire process of echo signal simulation.

[0109] It should be clear that the present application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications and additions, or change the order between steps after understanding the spirit of the present application.

[0110] In addition, the "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different parts.

[0111] As described above, only the specific implementation manners of the present application are concerned. Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the processes in the foregoing method embodiments and will not be repeated here. It should be understood that the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application.

Claims

1. A spaceborne interferometric imaging altimeter echo simulator, comprising: A radio frequency subsystem, configured to receive a first radio frequency transmission simulation signal and a second radio frequency transmission simulation signal transmitted by the spaceborne interferometric imaging altimeter, convert the first radio frequency transmission simulation signal into a first intermediate frequency transmission simulation signal, convert the second radio frequency transmission simulation signal into a second intermediate frequency transmission simulation signal, and transmit the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal to an intermediate frequency subsystem; The intermediate frequency subsystem is configured to receive the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal transmitted by the radio frequency subsystem, convert the first intermediate frequency transmission simulation signal and the second intermediate frequency transmission simulation signal into digital signals respectively, generate a first intermediate frequency transmission digital signal and a second intermediate frequency transmission digital signal, and packetize the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to generate an intermediate frequency transmission data packet; A sea surface echo calculation subsystem, configured to generate a first intermediate frequency echo digital signal and a second intermediate frequency echo digital signal corresponding to the sea surface imaging area of two antennas at each pulse moment based on the intermediate frequency transmission data packet transmitted by the intermediate frequency subsystem according to user settings, store the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, and packetize the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal to generate an intermediate frequency echo data packet; The intermediate frequency subsystem is further configured to receive the intermediate frequency echo data packet transmitted by the sea surface echo calculation subsystem under the control of a timing pulse signal output by the spaceborne interferometric imaging altimeter, decompose the intermediate frequency echo data packet into a first intermediate frequency echo digital signal and a second intermediate frequency echo digital signal, convert the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal into analog signals respectively, and generate a first intermediate frequency echo analog signal and a second intermediate frequency echo analog signal, wherein there is a set phase difference between the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal; The radio frequency subsystem is further configured to receive the first intermediate frequency echo analog signal and the second intermediate frequency echo analog signal transmitted by the intermediate frequency subsystem, convert the first intermediate frequency echo analog signal into a third radio frequency echo analog signal and a fourth radio frequency echo analog signal, convert the second intermediate frequency echo analog signal into a fifth radio frequency echo analog signal and a sixth radio frequency echo analog signal, and transmit the third radio frequency echo analog signal, the fourth radio frequency echo analog signal, the fifth radio frequency echo analog signal and the sixth radio frequency echo analog signal to the spaceborne interferometric imaging altimeter.

2. The spaceborne interferometric imaging altimeter echo simulator according to claim 1, wherein The radio frequency subsystem includes an attenuation component, and the attenuation component includes a first attenuator and a second attenuator, wherein: The first attenuator is configured to receive the first radio frequency transmission simulation signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the first radio frequency transmission simulation signal from a preset first threshold to a preset second threshold to obtain a third radio frequency transmission simulation signal; The second attenuator is configured to receive the second radio frequency transmission simulation signal sent by the spaceborne interferometric imaging altimeter and attenuate the power of the second radio frequency transmission simulation signal from the first threshold to the second threshold to obtain a fourth radio frequency transmission simulation signal.

3. The on-orbit interferometric imaging altimeter echo simulator according to claim 2, characterized in that The radio frequency subsystem further includes a down-conversion component, and the down-conversion component includes a first down-converter and a second down-converter, where: The first down-converter is configured to receive the third radio frequency transmission analog signal transmitted by the first attenuator and reduce the frequency of the third radio frequency transmission analog signal from a set third threshold to a set fourth threshold to obtain a first intermediate frequency transmission analog signal; The second down-converter is configured to receive the fourth radio frequency transmission analog signal transmitted by the second attenuator and reduce the frequency of the fourth radio frequency transmission analog signal from the third threshold to the fourth threshold to obtain a second intermediate frequency transmission analog signal.

4. The spaceborne interferometric imaging altimeter echo simulator according to claim 3, characterized in that, The intermediate frequency subsystem includes a first analog-to-digital converter ADC1, a second analog-to-digital converter ADC2, and a central controller, where: The first analog-to-digital converter ADC1 is configured to receive the first intermediate frequency transmission analog signal sent by the first down-converter, convert the first intermediate frequency transmission analog signal into a first intermediate frequency transmission digital signal, and then send it to the central controller; The second analog-to-digital converter ADC2 is configured to receive the second intermediate frequency transmission analog signal sent by the second down-converter, convert the second intermediate frequency transmission analog signal into a second intermediate frequency transmission digital signal, and then send it to the central controller; The central controller is configured to receive the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal, and packetize the first intermediate frequency transmission digital signal and the second intermediate frequency transmission digital signal to obtain the intermediate frequency transmission data packet, and transmit the intermediate frequency transmission data packet to the sea surface echo calculation subsystem.

5. The on-board interferometric imaging altimeter echo simulator according to claim 4, characterized in that, The sea surface echo calculation subsystem is further configured to, according to the intermediate frequency transmission data packet, the six orbital elements input by the user, the satellite attitude, the payload working mode, and the sea condition information, and adopt the linear superposition algorithm of the echo signal to obtain the intermediate frequency echo data corresponding to the sea surface imaging area at each pulse moment of the two antennas.

6. The spaceborne interferometric imaging altimeter echo simulator according to claim 5, characterized in that, The intermediate frequency subsystem further includes a first digital-to-analog converter DAC1 and a second digital-to-analog converter DAC2, where: The central controller is further configured to obtain the intermediate frequency echo data packet from the sea surface echo calculation subsystem, unpack the intermediate frequency echo data packet to obtain the first intermediate frequency echo digital signal and the second intermediate frequency echo digital signal, transmit the first intermediate frequency echo digital signal to the first digital-to-analog converter DAC1, and transmit the second intermediate frequency echo digital signal to the second digital-to-analog converter DAC2; The first digital-to-analog converter DAC1 is configured to convert the first intermediate frequency echo digital signal into a first intermediate frequency echo analog signal and transmit the first intermediate frequency echo analog signal to the radio frequency subsystem; The second digital-to-analog converter DAC2 is configured to convert the second intermediate frequency echo digital signal into a second intermediate frequency echo analog signal and transmit the second intermediate frequency echo analog signal to the radio frequency subsystem.

7. The on-orbit interferometric imaging altimeter echo simulator according to claim 6, characterized in that, The radio frequency subsystem includes an up-conversion component, and the up-conversion component includes a first up-converter and a second up-converter, where: The first upconverter is configured to receive the first intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the first intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a first radio-frequency echo analog signal; The second upconverter is configured to receive the second intermediate-frequency echo analog signal sent by the intermediate-frequency subsystem and increase the frequency of the second intermediate-frequency echo analog signal from the fourth threshold to the third threshold to obtain a second radio-frequency echo analog signal.

8. The spaceborne interferometric imaging altimeter echo simulator according to claim 7, characterized in that The radio-frequency subsystem further includes a power splitting component, and the power splitting component includes a first power splitter and a second power splitter, where: The first power splitter is configured to divide the first radio-frequency echo signal into a third radio-frequency echo signal and a fourth radio-frequency echo signal according to power and transmit the third radio-frequency echo signal to the first receiving channel of the spaceborne interferometric imaging altimeter; The second power splitter is configured to divide the second radio-frequency echo signal into a fifth radio-frequency echo signal and a sixth radio-frequency echo signal, and transmit the fifth radio-frequency echo signal to the second receiving channel of the spaceborne interferometric imaging altimeter.

9. The on-board interferometric imaging altimeter echo simulator according to claim 4, characterized in that, The central controller is the programmable logic hardware PL in the chip RFSoC.

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