CN113759802A

CN113759802A - Satellite-borne SAR load integrated processing platform and SAR system

Info

Publication number: CN113759802A
Application number: CN202111115001.7A
Authority: CN
Inventors: 高恩宇; 姜秀鹏; 周鑫; 孔令振
Original assignee: Beijing MinoSpace Technology Co Ltd
Current assignee: Beijing MinoSpace Technology Co Ltd
Priority date: 2021-09-23
Filing date: 2021-09-23
Publication date: 2021-12-07

Abstract

The application provides a satellite-borne SAR load integration processing platform and SAR system, include: the high-integration-level integrated control system comprises a master control module, a radio frequency module, a waveform generating and collecting module, an inner bus module and an outer bus module which are arranged in an integrated manner; the main control module is used for analyzing the working instruction sent by the satellite platform, generating a system control instruction and distributing the system control instruction to the radio frequency module and the waveform generating and collecting module; the radio frequency module is used for generating a reference clock signal and sending the reference clock signal to the waveform generating and collecting module, receiving and processing a linear frequency modulation signal of the waveform generating and collecting module to obtain a transmitting excitation signal, receiving an intermediate frequency echo signal sent by an antenna array surface and sending the intermediate frequency echo signal to the waveform generating and collecting module; the waveform generating and collecting module is used for generating a linear frequency modulation signal and outputting the linear frequency modulation signal to the radio frequency module; and receiving the intermediate frequency echo signal and carrying out digital processing to obtain echo acquisition data. The application reduces the number of single machines through high integration level board level design.

Description

Satellite-borne SAR load integrated processing platform and SAR system

Technical Field

The application relates to the field of satellite information processing, in particular to a satellite-borne SAR load integrated processing platform and an SAR system.

Background

The single machine function division of the central electronic equipment of the traditional satellite-borne SAR load system is clear and plays its own roles, and the number of single machines in the SAR system cabin is large. The cables between the single machines in the satellite cabin are complex to route, the structural layout of each single machine in the satellite cabin is difficult, the signal quality can be influenced by the layout, and particularly, the radio frequency unit routing easily causes mutual electromagnetic interference to further influence the performance index of the SAR system. The system has complex wiring and reasonable layout of a single machine, needs larger space in a satellite cabin for supporting, simultaneously increases the power consumption and the quality of the system, is suitable for military SAR satellites with particularly strict reliability requirements, has low commercial value and can not be applied to commercial lightweight microsatellite platforms; meanwhile, the SAR load single machine remote measurement quantity needing to be monitored by the traditional monitoring timing unit is increased, the system remote control instruction quantity is increased, the pressure of a main control part of the system is increased, and the software design is complex and is inconvenient for ground real-time control.

Disclosure of Invention

In view of this, an object of the present application is to provide an integrated processing platform for a satellite-borne SAR load and an SAR system, which reduce the number of single machines and reduce the requirement of the load on a satellite platform through a high-integration board level design.

The utility model provides a satellite-borne SAR load integration processing platform, processing platform includes: the high-integration-level integrated control system comprises a master control module, a radio frequency module, a waveform generating and collecting module, an inner bus module and an outer bus module which are arranged in an integrated manner;

the main control module is used for analyzing a working instruction which is received by the external bus module and sent by a satellite platform carried on a satellite to generate a system control instruction, and distributing the system control instruction to the radio frequency module and the waveform generating and collecting module through the internal bus module so that the radio frequency module and the waveform generating and collecting module respectively work according to the received system control instruction;

the radio frequency module is used for generating a reference clock signal and sending the reference clock signal to the waveform generating and collecting module; the receiving waveform generating and collecting module is used for processing the linear frequency modulation signal based on the linear frequency modulation signal generated by the reference clock signal to obtain a transmitting excitation signal and sending the transmitting excitation signal to an antenna array surface so that the antenna array surface transmits a detection wave facing the ground; receiving a radio frequency echo signal sent by an antenna array surface, processing the radio frequency echo signal to obtain an intermediate frequency echo signal, and sending the intermediate frequency echo signal to a waveform generating and collecting module; the radio frequency echo signal is a signal returned to an antenna array surface after the detection wave reaches a target object;

the waveform generating and collecting module is used for generating a linear frequency modulation signal according to a received system control instruction and the reference clock signal and outputting the linear frequency modulation signal to the radio frequency module; and receiving the intermediate frequency echo signal returned by the radio frequency module based on the linear frequency modulation signal, performing digital processing on the intermediate frequency echo signal to obtain echo acquisition data, and uploading the echo acquisition data to the satellite platform.

In some embodiments, the radio frequency module in the integrated processing platform for SAR load is further configured to send the generated reference clock signal to the main control module;

the main control module is specifically configured to receive the reference clock signal, and generate timing control signals for the radio frequency module and the waveform generation and acquisition module according to a pulse-per-second signal and a reference time broadcast signal sent by a satellite platform mounted on a satellite under the drive of the reference clock signal, so that the timing control signal for the waveform generation and acquisition module and a chirp signal generated by the waveform generation and acquisition module, the timing control signal for the timing control module, and the transmission excitation signal obtained by the radio frequency module based on the chirp signal are all generated based on the reference clock signal.

In some embodiments, the main control module in the satellite-borne SAR load integrated processing platform is specifically configured to determine whether a work instruction received through the external bus module is directed to the processing platform;

if yes, receiving and analyzing the working instruction and generating a system control instruction;

if not, no processing is performed.

In some embodiments, the internal bus module in the integrated processing platform for a satellite-borne SAR load specifically includes a first internal bus and a second internal bus;

the method for generating the system control instruction after the main control module receives and analyzes the working instruction specifically comprises the following steps: a time sequence control signal, a remote control instruction carrying a communication protocol and a satellite auxiliary data instruction; the time sequence control signal is transmitted to the waveform generation and acquisition module and the radio frequency module through the first internal bus; the remote control commands and satellite assistance data commands are forwarded to the waveform generation and acquisition module and radio frequency module via the second internal bus.

In some embodiments, the internal bus module in the integrated processing platform for a satellite-borne SAR load specifically further includes a third internal bus;

among the remote control command and the satellite auxiliary data command, the remote control command and the satellite auxiliary data command for the waveform generation and acquisition module are forwarded to the waveform generation and acquisition module through the third internal bus, so that the remote control command and the satellite auxiliary data command for the waveform generation and acquisition module are transmitted to the waveform generation and acquisition module within a preset time period.

In some embodiments, a board connector is respectively arranged between the radio frequency module, the waveform generating and collecting module and the main control module in the satellite-borne SAR load integrated processing platform;

the reference clock signal generated by the radio frequency module is sent to the main control module and the waveform generating and collecting module through the board connector.

In some embodiments, the satellite-borne SAR load integrated processing platform further includes a standby main control module;

when the satellite-borne SAR load is started, the main control module is powered on under the control of a starting instruction sent by a satellite platform carried on a satellite;

when the main control module is abnormal, the main control module is powered off and the standby main control module is powered on under the control of a switching instruction sent by a satellite platform carried on a satellite.

In some embodiments, the satellite-borne SAR load integrated processing platform further comprises a spare radio frequency module and a spare waveform generating and collecting module;

when the satellite-borne SAR load is started, under the control of a first starting instruction included in a system control instruction generated by the main or standby main control module, the main radio frequency module and the main waveform generating and collecting module are powered on;

when the active radio frequency module is abnormal, the active radio frequency module is powered off and the standby radio frequency module is powered on under the control of a first switching instruction included in a system control instruction generated by the active or standby main control module or a second power-on instruction sent by a satellite platform carried on a satellite;

when the active waveform generation and acquisition module is abnormal, the active waveform generation and acquisition module is powered off under the control of a second switching instruction included in a system control instruction generated by the active or standby main control module or under the control of a third switching instruction sent by a satellite platform carried on a satellite, and the standby waveform generation and acquisition module is powered on.

In some embodiments, the integrated processing platform for spaceborne SAR loads further includes: the power supply module is integrated with the main control module, the radio frequency module, the waveform generating and collecting module, the inner bus module and the outer bus module in high integration level;

and the power supply module is used for supplying power to the main control module, the radio frequency module and the waveform generating and collecting module under the control of the satellite platform and/or the main control module.

In some embodiments, a space-borne SAR system is further provided, where the space-borne SAR system includes the processing platform and a front antenna, and the front antenna completes the imaging observation to the ground under the control of the processing platform.

In the embodiment of the application, the processing platform adopts a highly integrated and integrally arranged single machine modularization design, and module division is carried out according to the functional requirements of each single machine of the central electronic equipment of the satellite-borne SAR system, so that the load in the satellite cabin is modularized. The single functions of the central electronic equipment are realized through the main control module, the power supply and distribution module, the radio frequency module and the waveform generation and acquisition module, the power consumption, the volume and the weight of the central electronic equipment of the whole SAR system are greatly reduced after modular design, the energy and space requirements of satellite-borne SAR loads on a satellite platform are reduced, meanwhile, the emission cost can be reduced, and the commercialization is facilitated.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic circuit structure diagram of a conventional satellite-borne SAR load system;

FIG. 2 is a schematic diagram of a circuit configuration of a processing platform according to an embodiment of the present application;

FIG. 3 is a schematic workflow diagram of a processing platform according to an embodiment of the present application;

FIG. 4 illustrates a schematic circuit diagram of a power module 302 of a processing platform according to an embodiment of the present application;

FIG. 5 is a schematic circuit diagram of a main control module 301 of the processing platform according to the embodiment of the present application;

FIG. 6 is a schematic circuit diagram of another master control module 301 of the processing platform according to the embodiment of the present application;

FIG. 7 is a diagram illustrating an example of timing control signals output by the main control module 301 of the processing platform according to the embodiment of the disclosure;

fig. 8 shows a schematic circuit diagram of the rf module 303 of the processing platform according to the embodiment of the present application;

FIG. 9 is a schematic circuit diagram of the waveform generation and acquisition module 304 of the processing platform according to the embodiment of the present application;

fig. 10 shows a flow chart of a method of BAQ compression as described in the embodiments described in the present application.

100. An antenna subsystem; 101. a transmitting antenna; 102. a receiving antenna; 103. an inner calibrator; 104. an antenna distributor; 105. a beam controller; 106. a radar distributor; 107. a monitoring timer; 108. a digital receiver; 109. a power amplifier; 1010. an analog receiver; 1011. a frequency modulation signal source; 1012. a conventional reference frequency source; 200. a satellite platform, 201 and a data transmission system; 202. an integrated electronic computer; 203. a satellite platform power supply; 301. a main control module; 3011. a timer module; 3012. a first FPGA chip; 3013. a DSP chip; 302. a power supply module; 3021. a power supply filter; 3022. a power distribution module; 303. a radio frequency module; 3031. a main and standby switch; 3032. a transmit-receive switch; 3033. a reference frequency source of the radio frequency module; 3034. a transmit channel module; 3035. a receiving channel module; 304. a waveform generation and acquisition module; 3041. an AD chip; 3042. a DA chip; 3043. a second FPGA chip; 305. a CAN bus; 306. RS-485 internal bus; 307. RS-422 internal bus; 308. an LVDS internal bus.

Detailed Description

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it should be understood that the drawings in the present application are for illustrative and descriptive purposes only and are not used to limit the scope of protection of the present application. Additionally, it should be understood that the schematic drawings are not necessarily drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of the present application. It should be understood that the operations of the flow diagrams may be performed out of order, and steps without logical context may be performed in reverse order or simultaneously. One skilled in the art, under the guidance of this application, may add one or more other operations to, or remove one or more operations from, the flowchart.

In addition, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that in the embodiments of the present application, the term "comprising" is used to indicate the presence of the features stated hereinafter, but does not exclude the addition of further features.

The Synthetic Aperture Radar (SAR) has all-weather earth imaging observation capability all day long, the satellite-borne SAR has the global detection advantage, global land and sea information can be acquired, and abundant radar image information is provided for multiple industries of environmental protection, disaster monitoring, target detection and identification, ground change detection, city planning and the like. Different from optical remote sensing, the SAR satellite can acquire a complex image of an observation area, namely the complex image simultaneously contains intensity information and phase information, and phase information of radar complex image data can be extracted to invert terrain and surface micro-change information through a synthetic aperture radar interferometry technology. Due to the characteristics, the SAR satellite has unique application value in the fields of land resources, geology, hydrology, mapping, military and the like. The L wave band has good penetration capability and is suitable for surface layer information acquisition and inversion, but the imaging resolution is limited, generally 3 m-10 m, and the aperture of the satellite-borne antenna is large (generally 10 m)²Above), a complicated folding and unfolding mechanism is required, and the device is generally suitable for satellites above 300 kg. The X wave band and the Ku wave band have high-resolution imaging capability, the imaging resolution is generally 0.3-3 m, but the X wave band and the Ku wave band do not have penetration capability, the aperture of the satellite-borne antenna is small, and the X wave band and the Ku wave band can be carried on a 30 kg-200 kg-level microsatellite platform 200.

At present, an existing satellite-borne SAR system mainly comprises a satellite cabin device and an external cabin device, wherein the internal cabin device is a central electronic device, and the external cabin device is an SAR antenna subsystem 100. As shown in fig. 1, the conventional satellite-borne SAR load system mainly includes an antenna subsystem 100, and a conventional reference frequency source 1012, a frequency modulation signal source 1011, a monitoring timer 107, a radar distributor 106, an analog receiver 1010, a power amplifier 109, a digital receiver 108, and other single-machine devices in a cabin. The antenna subsystem 100 includes a transmit antenna 101, a receive antenna 102, an inner calibrator 103, an antenna power distributor 104, and a beam controller 105. The single equipment in the cabin is divided into digital equipment and radio frequency equipment, and specifically, the radar distributor 106, the monitoring timer 107 and the digital receiver 108 are digital equipment; the power amplifier 109, analog receiver 1010, frequency modulated signal source 1011, and conventional reference frequency source 1012 are radio frequency devices.

The single-machine equipment in the cabin is responsible for completing the generation, emission, excitation and output of the local oscillation frequency, the sampling clock, the timing pulse and the linear frequency modulation signal of the high-precision system, performing gain control and dynamic adjustment of radar echo signals, converting the signals into quantized digital signals after frequency conversion and data acquisition, forming formatted data with radar auxiliary data and transmitting the formatted data to the satellite data transmission system 201.

Meanwhile, the satellite-borne SAR system controls and monitors all the single-machine equipment and the antenna subsystem 100 in the system so as to ensure normal operation of multi-mode operation. The monitoring timer 107 mainly completes communication with a satellite platform 200 carried on a satellite, executes corresponding actions according to commands of a comprehensive electronic computer 202 in the satellite platform 200, collects monitoring signals of other single machines in the SAR subsystem and completes the output of timing pulses and the control function of system time sequence; the reference signal source provides a full-coherent working clock for the system; a frequency modulation signal source 1011 generates an SAR system excitation signal, and the signal form is generally a linear frequency modulation signal; the analog receiver 1010 and the digital receiver 108 complete the receiving, frequency mixing and digitization of SAR system echo signals, and finally form SAR system echo image data; the radar distributor 106 is mainly used for completing power supply distribution, protection and telemetering signal transmission of central electronic equipment of the SAR subsystem.

Specifically, the functions and the working principle of each single computer in the central electronic device are as follows:

(1) the monitoring timer 107:

the monitoring timer 107 is the brain of the space-borne SAR system and is generally divided into two parts, namely a radar computer and a radar timer.

The radar computer mainly completes communication (remote control instruction and telemetering information) with the satellite platform 200, specifically receives the remote control instruction issued by the integrated electronic computer 202 and collects the telemetering information of the SAR system; the radar timer mainly completes the output of timing pulse and the control function of system time sequence. The specific functions are that the system is communicated with the integrated electronic computer 202, receives indirect remote control instructions and satellite auxiliary data injected by the integrated electronic computer 202, completes the unpacking, storage and execution of the instructions, and uploads the telemetering data of a single machine in the SAR system; the radar computer performs power-on and power-off control on the power supply of the single-machine equipment in the cabin according to the remote control instruction sent by the comprehensive electronic computer 202 to complete the on-off of each single machine; the system is communicated with each single machine device in the satellite-borne SAR system, and is used for collecting monitoring signals in the satellite-borne SAR system and receiving remote measurement information of each single machine in the satellite-borne SAR system; controlling the satellite-borne SAR system to be in a working mode or a calibration mode; sending a working mode command and a wave position parameter to the antenna subsystem 100 to control the antenna beam pointing; and finishing time management and performing system time sequence control. The radar computer is generally realized by a singlechip, an ARM or a DSP, and the radar timer is generally realized by an FPGA.

(2) Frequency synthesizer (conventional reference frequency source 1012, fm signal source 1011):

the frequency synthesizer provides a full-coherent working clock, a radio frequency excitation signal and a calibration signal for the satellite-borne SAR system, and generally comprises a high-stability crystal oscillator, a frequency sweep signal generator, an up-converter, a filter and other circuits. The frequency synthesizer outputs a reference clock by a high-stability crystal oscillator, and stably outputs a full-coherent clock reference signal required by the whole system by phase locking, one path of the clock reference signal is subjected to power division and then is subjected to generation of a broadband linear frequency modulation signal by a sweep frequency signal generator (DA chip 3042), the signal generated by the DA is subjected to frequency conversion and then is filtered and amplified to form a sweep frequency excitation signal and a calibration signal, and the other path of the reference signal is subjected to up-conversion and filtering to generate a system local oscillator signal.

(3) Radar power distributor 106

The radar distributor 106 mainly completes power supply distribution, protection and telemetering signal transmission of central electronic equipment of the SAR system, provides an interface for monitoring and controlling the running state of each single machine of the system for the monitoring timer 107, and the radar distributor 106 completes the power on/off control function of each single machine of the central electronic equipment by utilizing the on/off of a relay contact.

(4) Analog receiver 1010

The analog receiver 1010 mainly functions to receive the echo signal output by the sub-system 100R of the antenna 102 and the local oscillator signal output by the frequency synthesizer, complete frequency conversion processing, and output an intermediate frequency echo signal. And when the SAR system works in a calibration mode, the frequency conversion processing of the calibration signal is completed and the intermediate frequency calibration signal is output. The analog receiver 1010 generally comprises circuits such as low noise amplifier, mixer, power amplifier, power divider, circulator, and switch.

(5) Digital receiver 108

The digital receiver 108 is also called a data former, and mainly functions to receive the sampling command from the monitoring timer 107, and complete the acquisition of the analog signal output by the analog receiver 1010 according to the reference clock provided by the external frequency synthesizer. The echo signals are subjected to digital signal processing, such as digital down conversion, filtering, decimation, compression, imaging, etc., according to system design requirements. In engineering implementation, the digital receiver 108 is generally implemented by an ADC and a processor, and the processor commonly used includes an FPGA, a DSP, and the like.

According to the above discussion, the single machine function of the central electronic equipment of the conventional satellite-borne SAR load system is clearly divided and each of the electronic equipment plays its own role, and the number of single machines in the SAR system cabin is large. The cables between the single machines in the satellite cabin are complex to route, the structural layout of each single machine in the satellite cabin is difficult, the signal quality can be influenced by the layout, and particularly, the radio frequency unit routing easily causes mutual electromagnetic interference to further influence the performance index of the SAR system. The system has complex wiring and reasonable layout of a single machine, needs larger space in a satellite cabin for supporting, simultaneously increases the power consumption and the quality of the system, is suitable for military SAR satellites with particularly strict reliability requirements, has low commercial value and cannot be applied to the commercial light-weight microsatellite platform 200; meanwhile, the SAR load single machine remote measurement quantity needing to be monitored by the traditional monitoring timing unit is increased, the system remote control instruction quantity is increased, the pressure of a main control part of the system is increased, and the software design is complex and is inconvenient for ground real-time control.

With the progress of microelectronic technology and manufacturing technology, the miniaturization of satellites is accelerated, and modern microsatellites have the characteristics of low weight and small volume. Meanwhile, the modern small satellite has wide application, and can be applied to various fields of communication, earth observation, space remote sensing, meteorological observation, ocean exploration, scientific research and the like. Due to the functional requirements and platform characteristics, the requirements for loads are higher and higher. Modern small satellites need to be small and cheap, and implementation of integrated design is a good choice, especially for carrying loads. The SAR load system carried by the satellite-borne SAR satellite has the characteristics of large power, large antenna array surface, complex electronic system, high time sequence requirement, complex test experiment, high signal and information processing difficulty and the like, so that the requirement on the satellite platform 200 is higher than that of other types of remote sensing satellites, and the difficulty of the satellite-borne SAR remote sensing commercialization is further increased.

Based on this, the present application provides a satellite-borne SAR load integrated processing platform, as shown in fig. 2, the processing platform includes: the system comprises a main control module 301, a radio frequency module 303, a waveform generating and collecting module 304, an internal bus module and an external bus module which are high in integration level and are arranged integrally;

the main control module 301 is configured to analyze a work instruction received by the external bus module and sent by the satellite platform 200 mounted on a satellite, generate a system control instruction, and distribute the system control instruction to the radio frequency module 303 and the waveform generation and acquisition module 304 by the internal bus module, so that the radio frequency module 303 and the waveform generation and acquisition module 304 work according to the received system control instruction respectively;

the radio frequency module 303 is configured to generate a reference clock signal and send the reference clock signal to the waveform generating and acquiring module 304; the receiving waveform generating and collecting module 304 processes the chirp signal generated based on the reference clock signal to obtain a transmitting excitation signal, and sends the transmitting excitation signal to an antenna array surface so that the antenna array surface transmits a detection wave facing the ground; receiving a radio frequency echo signal sent by an antenna array surface, processing the radio frequency echo signal to obtain an intermediate frequency echo signal, and sending the intermediate frequency echo signal to a waveform generating and collecting module 304; the radio frequency echo signal is a signal returned to an antenna array surface after the detection wave reaches a target object;

the waveform generating and collecting module is configured to generate a chirp signal according to a received system control instruction and the reference clock signal, and output the chirp signal to the radio frequency module 303; and receiving the intermediate frequency echo signal returned by the radio frequency module 303 based on the chirp signal, performing digital processing on the intermediate frequency echo signal to obtain echo acquisition data, and uploading the echo acquisition data to the satellite platform 200.

In the embodiment of the application, the processing platform adopts a highly integrated and integrally arranged single machine modularization design, and module division is carried out according to the functional requirements of each single machine of the central electronic equipment of the satellite-borne SAR system, so that the load in the satellite cabin is modularized. The single functions of the central electronic equipment are realized through the main control module 301, the power supply and distribution module 3022, the radio frequency module 303 and the waveform generation and acquisition module 304, the power consumption, the volume and the weight of the central electronic equipment of the whole SAR system are greatly reduced after modular design, the energy and space requirements of satellite-borne SAR loads on the satellite platform 200 are reduced, meanwhile, the emission cost can be reduced, and the commercialization is facilitated.

The processing platform with the integrated design enables the weight of central electronic equipment of the SAR system with the processing platform to be controlled to be about 10kg, and meanwhile, the peak power consumption is controlled to be within 120W, so that the requirement on the satellite platform 200 is greatly reduced.

Specifically, the processing platform further includes: a power module 302 which is integrated with the main control module 301, the radio frequency module 303, the waveform generating and collecting module 304, the internal bus module and the external bus module;

the power module 302 is configured to supply power to the main control module 301, the radio frequency module 303, and the waveform generating and collecting module 304 under the control of the satellite platform 200 and/or the main control module 301.

As shown in fig. 3, the work flow of the processing platform is as follows:

the power supply module 302 receives primary bus power supply of the satellite platform power supply 203, the power supply module 302 converts primary bus power supply voltage into power supply voltage +/-5V, 6.3V and 8V required by the interior of equipment, power is supplied to the main control module 301 through an internal magnetic latching relay, and the main control module 301 controls the on and off of other modules in the processing platform through OC instructions in a system control finger; a comprehensive electronic computer 202 in a satellite platform 200 carried on a satellite controls the on-off operation of a satellite-borne integrated processing platform main control module 301; the main control module 301 realizes the long embracing test of the internal bus through the CAN protocol, then judges the working mode of the main control module according to the working instruction of the integrated electronic computer 202 in the satellite platform 200, and performs corresponding data processing to complete the operation of other internal functional modules;

each functional module receives the corresponding data information of the main control module 301 through the internal bus, completes the corresponding work response, and sends the corresponding data to the main control module 301 through the internal bus.

In some embodiments, the power module 302 converts, distributes, and controls the dc power 28V provided on the satellite platform 200 to generate the power voltages required by the modules in the processing platform. And meanwhile, an output telemetering interface for voltage is provided for judging the working state of the power supply module 302, and the output telemetering interface also has the functions of input surge suppression, output overcurrent protection and output overvoltage protection.

The circuit structure of the power supply module 302 is shown in fig. 3 and 4, and the power supply module 302 includes a power supply board for implementing voltage conversion, a power supply filter 3021 and a power distribution module 3022. Wherein, the power supply board can adopt a multi-path DC-DC module.

The power supply board in the power supply module 302 converts the externally provided primary bus power (28V ± 3V) into the ± 5V, +6.3V, +8V secondary power required inside the processing platform, and then transmits the secondary power to the power distribution module 3022 in the power supply module 302, and the power distribution module 3022 completes the power distribution function of each function module inside the device. Wherein, the externally provided auxiliary bus power supply (28V ± 1V) is used for coil driving power supply of all relays in the power module 302.

In this embodiment, the main control module 301 includes an active main control module 301 and a standby main control module 301; the voltage of the secondary power supply required by the main control module 301 is +5V-1 main power supply and +5V-1 standby power supply, the frequency source module +6.3V-1 crystal oscillator main power supply and +6.3V-1 crystal oscillator standby power supply are directly electrified to work as a long electrification function module of the processing platform, the +6.3V-2 frequency source main power supply and the +6.3V-1 crystal oscillator main power supply are led out from one DC/DC channel (+6.3V-2 frequency source standby power supply and the +6.3V-1 crystal oscillator standby power supply are led out from one DC/DC channel), the +6.3V-2 frequency source power supply is controlled by a relay switch to be switched on and switched off, and a switching-on/off instruction is sent by the main control module 301; the rest secondary power supplies send on-off control instructions by the main control module 301 to control the on-off of the power supplies and the switching of the main power supply and the standby power supply, and the switching of the on-off is realized by a magnetic latching relay.

The primary bus enters the power filter 3021 dedicated to the power module 302 after being isolated and protected by the fuse and the relay, and then enters the power module 302 for power conversion. The secondary power supply conversion circuit consists of a plurality of DC-DC modules, and the DC-DC modules are respectively converted into +5V, -5V, +6.3V and +8V power supplies to supply power to the main control module 301, the radio frequency module 303 and the waveform generation and acquisition module 304. According to the working requirement of the satellite-borne SAR system on the integrated processing platform, the frequency source crystal oscillator needs to be powered on firstly, and needs to be kept in a power-on state without being powered off all the time after being powered on, so that a continuous reference time sequence can be provided for other modules, and the frequency source crystal oscillator adopts a cold backup design for ensuring the reliability of the system; the main control module 301 is powered on after obtaining the time sequence, and the power on is earlier than other working modules; after the master control normally works, the master control module 301 controls the power supply module 302 to supply power to other modules. And after the satellite OBC receives the load starting-up instruction, the bus switch is opened, wherein the +5V-1 and +6.3V-1 main/standby switches 3031 are controlled by the satellite OBC, and the main switch is opened under the default condition. The crystal oscillator and the main control module 301 are powered on normally in the load working process, after the main control module works normally, the main control module 301 controls the power distribution module 3022 to turn on +5V-2, +5V-3, +8V, +6.3V-2, and-5V secondary switches in sequence, and the integrated processing platform is powered on. The design of the secondary power supply DCDC module is realized by adopting a high-quality power supply conversion chip of VPT company, and the +5V-1, +5V-3 and-5V power supplies are output by the power supply conversion chip DVHE 2805S; the +5V-2 power supply is realized by a power conversion chip DVTR 2805S; the +8V power supply is realized by a power conversion chip DVTR 2808S; the +6.3V power supply is realized by a power conversion chip DVFL286R 3D. The power distribution module 3022 uses a magnetic latching relay 2JB5-1-28B as a switch, and the input control pulse signal duration pulse width supports two types of 160ms +/-10 ms/80ms +/-10 ms.

Specifically, the internal bus module includes a first internal bus and a second internal bus;

the generating of the system control instruction after the main control module 301 receives and analyzes the work instruction specifically includes: a time sequence control signal, a remote control instruction carrying a communication protocol and a satellite auxiliary data instruction; the timing control signal is transmitted to the waveform generation and acquisition module and the radio frequency module 303 through the first internal bus; the remote control commands and satellite assistance data commands are forwarded to the waveform generation and acquisition module and radio frequency module 303 through the second internal bus.

In some embodiments, the internal bus module specifically further includes a third internal bus, and among the remote control command and the satellite auxiliary data command, the remote control command and the satellite auxiliary data command for the waveform generation and acquisition module are forwarded to the waveform generation and acquisition module through the third internal bus, so that the remote control command and the satellite auxiliary data command for the waveform generation and acquisition module are transmitted to the waveform generation and acquisition module within a preset time period. The waveform generation and acquisition module keeps time consistency with the acquired echo data, and each frame of echo data acquired by the waveform generation and acquisition module is consistent with the height time of the working mode, time, positioning and orbit determination at the moment and is packaged in the same frame of data, so that higher requirements on real-time performance are met, and the transmission efficiency of the waveform generation and acquisition module must be ensured.

In some embodiments, the first internal bus is an RS-485 internal bus 306, the second internal bus is an RS-422 bus, the third internal bus is an LVDS internal bus 308, and the external bus is a CAN bus 305.

In some embodiments, in the satellite-borne SAR load integrated processing platform, a board connector is respectively arranged between the radio frequency module 303, the waveform generating and collecting module and the main control module 301; the reference clock signal generated by the rf module 303 is sent to the main control module 301 and the waveform generating and collecting module through the board connector.

The satellite-borne SAR load integrated processing platform comprises a digital circuit and an analog radio frequency circuit, wherein a main control module 301, a power supply module 302 and a waveform generation and acquisition module 304 are mainly digital circuits, the three sub-modules are connected together through a customized motherboard to complete power distribution and remote control and telemetering communication among the modules, control signals among the modules complete communication through an RS485 internal bus 306, an LVDS internal bus 308 and the like, a reference clock signal belongs to an analog signal, and the communication among the modules is completed through board connectors of the modules.

Different types of signals in the processing platform are transmitted through different internal buses or board connectors, and fig. 2 shows a signal transmission flow of the processing platform according to the embodiment of the present application, which is specifically as follows:

the main control module 301 realizes data interaction with the integrated electronic computer 202 through the CAN bus 305, and receives the uplink injection number of the responder in the satellite platform 200 through the RS-422 bus; the power supply module 302 receives a remote control signal of the integrated electronic computer 202 for the power supply module 302 and uploads a telemetry signal of the power supply module 302 to the integrated electronic computer 202;

the main control module 301 communicates with the radio frequency module 303 and the waveform generating and collecting module 304 through an RS-485 internal bus 306; a time sequence control instruction is sent to the radio frequency module 303 and the waveform generating and collecting module 304 through an RS-422 internal bus 307; wherein, the remote control signal and the auxiliary data aiming at the waveform generating and collecting module 304 in the system control signal are transmitted through the LVDS internal bus 308;

the reference clock signal generated by the rf module 303 is transmitted to the main control module 301 and the waveform generating and collecting module 304 through the board connector.

The main control module 301, the power supply and distribution module 3022, and the waveform generation and acquisition module 304 realize data communication through inter-board internal buses (an RS485 internal bus 306 and an LVDS internal bus 308), so that the number of cables and wires between single units is reduced, the internal buses can meet most communication requirements, and communication between modules can be realized without changing hardware modules when the requirements of the SAR system are changed.

The main control module 301 is mainly used for implementing the control function of each module in the processing platform. The main control module 301 receives an indirect remote control instruction and satellite auxiliary data injected by the satellite OBC, and simultaneously transmits telemetering data such as states and parameters of each part of equipment of the radar to the satellite OBC; and wave control communication is carried out with the wave control of the wave front on the SAR antenna wave front, wave control codes and receiving and transmitting time sequences are generated and sent to the wave control of the wave front, and the monitoring state sent by the wave control of the wave front is collected. And finishing the power-off control of main and standby of each extension in the cabin, and finishing the mode control and parameter setting of radar imaging and radar calibration. And receiving the pulse-per-second signal of the satellite platform 200 to realize the system timing of the whole machine.

The main control module 301 receives a sent work instruction output by a satellite OBC in the satellite platform 200 through the CAN bus 305, generates a system control instruction, and forwards an instruction in the system work instruction for the power module 302, the radio frequency module 303, and the waveform generation and acquisition module 304 to a corresponding module.

Specifically, when the main control module 301 receives a sent work instruction output by a satellite OBC in the satellite platform 200 through the CAN bus 305, a master-slave response mode is adopted in a data transmission process, that is, the main control module 301 is specifically configured to determine whether the work instruction received through the external bus module is directed to the processing platform;

if not, no processing is performed.

Similarly, when the power module 302, the radio frequency module 303 and the waveform generating and collecting module 304 receive the system control instruction, which is forwarded by the main control module 301 and is directed to the module, through the internal bus module, the master-slave response mode is also adopted, that is, the power module 302, the radio frequency module 303 and the waveform generating and collecting module 304 specifically determine whether the system work instruction received through the internal bus module is directed to the module;

if the module is aimed at, the working instruction is received and analyzed, and a system control instruction is generated;

if not, no processing is performed.

The system control instruction includes a power supply switching instruction of the power supply module 302, and the power supply switching instruction of the power supply module 302 can be used as a power on/off command of other modules to control the power on/off control of the waveform generation and acquisition module and the active and standby modules of the radio frequency module 303. The system control instruction also comprises a working mode instruction and a parameter setting instruction of the processing platform, and is used for determining the working mode of the processing platform and setting the parameters of each module of the processing platform.

In this embodiment of the application, the main control module 301 is designed in a cold backup manner, and the main backup design is consistent.

That is, in this embodiment of the application, the processing platform further includes a standby main control module 301;

when the satellite-borne SAR load is started, the main control module 301 is powered on under the control of a starting instruction sent by a satellite platform 200 carried on a satellite;

when the active main control module 301 is abnormal, the active main control module 301 is powered off and the standby main control module 301 is powered on under the control of a switching instruction sent by the satellite platform 200 mounted on a satellite.

Meanwhile, in the embodiment of the application, the satellite-borne SAR load integrated processing platform further comprises a standby radio frequency module 303 and a standby waveform generating and collecting module;

when the satellite-borne SAR load is powered on, under the control of a first power-on instruction included in a system control instruction generated by the main or standby main control module 301, the main radio frequency module 303 and the main waveform generation and acquisition module are powered on;

when the active radio frequency module 303 is abnormal, under the control of a first switching instruction included in a system control instruction generated by the active or standby main control module 301, or under the control of a second power-on instruction sent by a satellite platform 200 mounted on a satellite, the active radio frequency module 303 is powered off, and the standby radio frequency module 303 is powered on;

when the active waveform generation and acquisition module is abnormal, the active waveform generation and acquisition module is powered off under the control of a second switching instruction included in a system control instruction generated by the active or standby main control module 301 or under the control of a third switching instruction sent by the satellite platform 200 carried on a satellite, and the standby waveform generation and acquisition module is powered on.

As shown in fig. 5, the main control module 301 mainly comprises three parts, a CPU module, a timer module 3011 and an external interface module. The main control module 301 adopts a mode of FPGA + CPU, the FPGA receives a system reference clock signal and realizes the generation of a SAR system time sequence control signal; the CPU completes the functions of the central computer, the analysis of the system upper note instruction and the control function of the SAR system.

Specifically, the CPU module is implemented by the loongson 1E04 and the interface chip 1F 04. The CPU module and the timer module 3011 are the whole brain of the SAR system equipped with the processing platform, and control the SAR system to operate according to the system requirements. The CPU module is used as a master controller to complete the analysis of system control instructions, and the Loongson 1F04 is used as an interface chip to output the communication of the RS-485 internal bus 306.

The timer in the main control module 301 generates a time sequence control signal according to a system working mode instruction in the system control instruction, and controls the on-off of the switch matrix of the radio frequency module 303, so as to complete the generation and the off of the excitation signal and the calibration signal of the SAR system. The timer is realized by an antifuse type FPGA, the FPGA receives working parameters in a system control instruction to generate an SAR system time sequence control signal, and the working time sequence of the satellite-borne SAR system is controlled.

Specifically, the timer module 3011 is implemented by an FPGA A3PE3000L based on FLASH and antifuse technology, and the FPGA generates a timing control signal required by the SAR system according to a working mode and a system parameter in a system control instruction output by the CPU module to control the SAR system to work, and at the same time, the FPGA serves as an expansion interface chip to implement command reception and remote measurement output from a CAN external bus; the pulse-per-second signal sent by the satellite platform 200 and the reference clock sent by the radio frequency module 303 are directly received through the mixed connector, and the timing control signal is output through the RS-422 sending interface.

In some embodiments, according to the functional division of the main control module 301, as shown in fig. 6, the main control module 301 of the SAR integrated processing platform includes a first FPGA chip 3012 and a DSP chip 3013.

Specifically, the FPGA completes the function of the radar timer under the control of the DSP. The FPGA is used as a peripheral of the DSP, and generates a time sequence control signal and a mode control signal required by the interior of the SAR system under the control of the DSP, so as to realize an external communication interface. The FPGA adopts ACTEL antifuse type A54SX72A chips, and the maximum working frequency can reach 250 MHz. The DSP chip 3013 is made of SMV320C6701 manufactured by TI company, and the highest clock frequency is 167 MHz. When the chip works, the SMV320C6701 system clock frequency is set to be 100MHz, the external clock frequency is 25MHz, and 4-time multiplication is carried out through a PLL phase-locked clock circuit in the chip.

Specifically, the radio frequency module 303 is further configured to send the generated reference clock signal to the main control module 301;

the main control module 301 is specifically configured to receive the reference clock signal, and generate timing control signals for the radio frequency module 303 and the waveform generation and acquisition module according to a pulse-per-second signal and a reference time broadcast signal sent by a satellite platform 200 mounted on a satellite under the drive of the reference clock signal, so that the timing control signal for the waveform generation and acquisition module and a chirp signal generated by the waveform generation and acquisition module, the timing control signal for the timing control module, and the transmit excitation signal obtained by the radio frequency module 303 based on the chirp signal are all generated based on the reference clock signal, so as to ensure that the entire processing platform has homologous coherence.

That is, the timer of the main control module 301 receives the 10MHz reference clock signal generated by the radio frequency module 303, controls the processing platform to enter the calibration module or the imaging mode according to the ground injection instruction, and generates a corresponding timing control signal when the processing platform responds to the working mode under the driving of the 10MHz reference clock signal.

Wherein, when the main control module 301 generates the timing control under the driving of the 10MHz reference clock signal, the satellite GNSS receiver outputs 1 GNSS time reference pulse (i.e. pulse-per-second signal) to the master control module 301 at every UTC whole second time, within 50ms, the satellite GNSS receiver actively sends the reference time broadcast corresponding to the time to the CAN bus 305, and after receiving the broadcast time code of the reference time broadcast, the monitoring software in the main control module 301, the local time of the processing platform is calibrated in the interrupt service routine, and after the timer module 3011 receives the pulse of seconds, the 10M reference clock from the reference frequency source 3033 of the radio frequency module is used for clock counting to form high-precision relative time which is used as high-precision reference time for SAR load work, and outputting the time sequence control signal to control the processing platform and the SAR system comprising the processing platform to work according to the working mode requirement of the processing platform.

As shown in fig. 7, the output timing control signal includes a PRF pulse repetition periodic signal, a transmission synchronization signal, a transmission gating signal, a reception gating signal, a sampling start signal, and a wave position switching signal, so as to control the SAR system to perform periodic detection, in each detection period, the timing of the transmission channel of the radio frequency module 303 matches the timing of the switch of the reception channel, the timing of the switch of the reception channel of the radio frequency module 303 matches the timing of the sampling start of the waveform generation and acquisition module 304, and the timing of the sampling start signal of the waveform generation and acquisition module 304 matches the timing of the berth switching in one sampling period, so that the SAR system performs periodic detection smoothly.

The radio frequency module 303 mainly implements a function of a satellite-borne SAR system frequency synthesizer receiver, as shown in fig. 8, the radio frequency module 303 includes an active radio frequency module 303, a standby radio frequency module 303, an active/standby switch 3031, and a transceiver switch 3032; the active radio frequency module 303 and the standby radio frequency module 303 each include a reference frequency source 3033, a transmission channel module 3034, a reception channel module 3035, and the like of the radio frequency module. The main/standby switch 3031, the transmit/receive switch 3032 and other switches are arranged in a switch matrix. The reference frequency source 3033 of the rf module includes a constant temperature crystal oscillator and a frequency division and multiplication circuit.

The reference frequency source 3033 of the rf module generates the required reference clock signal for the processing platform and the onboard processing platform, the transmit channel module 3034 filters, mixes, filters, and amplifies the chirp signal (at this time, the chirp signal is an intermediate frequency signal) received from the waveform generating and collecting module 304 to obtain a transmit excitation signal (the transmit excitation signal is a radio frequency signal), the transmit excitation signal is output to the antenna array of the SAR system via the transmit receive switch 3032, the receiving channel module 3035 performs filtering, amplification, frequency mixing, filtering, amplification on the radio frequency echo signal sent by the antenna array surface, outputs the radio frequency echo signal to the analog demodulator to obtain an intermediate frequency echo signal, and sends the processed intermediate frequency echo signal to the waveform generating and collecting module 304 to digitize the processed intermediate frequency echo signal.

The reference frequency source 3033 of the radio frequency module adopts a constant temperature crystal oscillator, and a reference clock signal generated by the constant temperature crystal oscillator is subjected to frequency division, frequency multiplication, frequency mixing, amplification and the like to obtain local oscillation signals (including local oscillation signals required by down conversion of a receiving channel and local oscillation signals required by up conversion of a transmitting channel) of a receiving channel and a transmitting channel of the radio frequency module 303, and meanwhile, the reference clock signal, a sampling clock signal, a DA clock signal and the like are provided for the main control module 301 and the waveform generating and collecting module.

Specifically, the workflow of providing the reference clock signal, the sampling clock signal and the DA clock signal for the main control module 301 and the waveform generating and collecting module is as follows: when the processing platform works, the constant-temperature crystal oscillator is powered up in advance, a reference frequency source 3033 module of the radio frequency module outputs a reference clock signal, the reference clock signal is transmitted to the main control module 301 to drive the main control module 301 to generate a time sequence control signal, and a transmitting gating signal and a receiving gating signal in the time sequence control signal control the on-off of a receiving and transmitting switch 3032 of a receiving and transmitting channel of the radio frequency module 303. Meanwhile, the reference clock signal is transmitted to the waveform generating and collecting module, so as to provide a sweep frequency clock for the waveform generating and collecting module 304, and the generation of the broadband intermediate frequency chirp signal is realized through the sweep frequency signal generator (DA chip 3042). The sweep frequency signal generator in the waveform generating and collecting module 304 and the timer in the main control module 301 adopt the same source clock, so that clock jitter does not exist, random jitter does not exist between pulses, and the coherence characteristic of the system is ensured.

Specifically, the constant temperature crystal oscillator of the reference frequency source 3033 of the radio frequency module selects a 100MHz high-stability low-phase-noise crystal oscillator, and the main reference frequency source and the standby reference frequency source are alternately backed up and output, and generate a 10MHz system reference clock signal after frequency division, and send the signal to the main control module 301 timer; generating a 1.8GHz sampling clock signal and a 2.4GHz DA reference clock signal after frequency multiplication, and sending the signals to the waveform generating and collecting module 304; specifically, the 1.8GHz sampling clock signal is sent to an ADC chip in the waveform generating and collecting module 304, specifically, the 2.4GHz DA reference clock signal is sent to a DAC chip in the waveform generating and collecting module 304, and meanwhile, the 100MHz high-stability clock is sent to a dielectric oscillator (PDRO) as a reference, and an 8.25GHz local oscillation signal is output.

When the processing platform or the SAR system provided with the processing platform works in a transmitting state: the transceiver switch 3032 of the rf module 303 opens the transmitting channel and closes the receiving channel, the DA chip 3042 of the waveform generating and collecting module 304 outputs a chirp signal with a carrier bandwidth of 60MHz of 135MHz, and the chirp signal is subjected to frequency multiplication, filtering and amplification to obtain a signal of 1.35GHz, and the bandwidth is broadened to 600 MHz. And mixing the 8.25GHz local oscillation signal with the 1.35GHz linear frequency modulation signal, filtering difference frequency and sum frequency to obtain a 9.6GHz transmitting excitation signal.

When the processing platform or the SAR system provided with the processing platform works in a receiving state: the transceiving switch 3032 of the radio frequency module 303 opens the receiving channel and closes the transmitting channel, the echo signal of the antenna array received by the radio frequency is filtered and amplified and then mixed with the local oscillator signal of 8.25GHz, and the intermediate frequency echo signal of 1.35GHz +/-300 MHz is generated after down conversion.

The waveform generating and collecting module 304 is configured to generate a corresponding chirp signal according to the system control instruction generated by the main control module 301, perform sampling, extraction, digital filtering, data conditioning and compression on the intermediate frequency echo signal sent by the radio frequency module 303, and send the data to the data transmission terminal of the satellite platform 200.

The work flow of the waveform generation and acquisition module is as follows: the waveform generating and collecting module 304 receives the intermediate frequency echo signal output by the receiving channel of the radio frequency module 303, and performs sampling processing on the intermediate frequency echo signal; receiving a 1.8GHz sampling clock signal output by a reference frequency source 3033 of the radio frequency module as an AD sampling clock; receiving a sampling start signal in the timing control signal output by the timer of the main control module 301 as a sampling trigger signal of the AD chip 3041; receiving a 2.4GHz DA clock output by a frequency source of the radio frequency module 303 as a reference clock of a linear frequency modulation signal; receiving the remote control signal and the auxiliary data aiming at the waveform generation and acquisition module 304 in the system control signal of the main control module 301 through the LVDS internal bus 308, analyzing the received auxiliary data of the remote control signaling machine and responding, detecting the waveform generation and acquisition module 304 to obtain a telemetering signal representing the waveform generation and acquisition signal, and sending the telemetering signal to the main control module 301; generating an ACG control code according to the amplitude of the sampled intermediate frequency echo signal, and sending the ACG control code to the main control module 301 through an RS485 internal bus 306; and sending a combined data frame to a data transmission terminal of the satellite platform 200, wherein the combined data frame comprises echo acquisition data obtained by digitizing the intermediate frequency echo signal and auxiliary data such as imaging parameters, bus time codes, orbit determination positioning data, key telemetry parameters and the like of the processing platform.

The waveform generation and acquisition module also adopts a cold standby design, the design of a main machine and a standby machine is kept consistent, and the main control module 301 controls a power distribution module 3022 relay to realize the switching of the main machine and the standby machine.

A schematic circuit block diagram of the waveform generating and collecting module 304 is shown in fig. 9, where the waveform generating and collecting module 304 includes an uplink module and a downlink module, the uplink module is implemented as waveform generation, and the downlink module collects echo collection data. The uplink module and the downlink module are specifically disposed in a second FPGA chip 3043.

The uplink portion generates a chirp signal required by the radio frequency module 303 of the processing platform, and is mainly implemented by a second FPGA chip 3043 and a DA chip 3042. The uplink part DA sampling clock is generated by the reference frequency source 3033 of the radio frequency module, and it is ensured that the whole processing platform is coherent, and the DA chip 3042 generates and outputs an intermediate frequency chirp signal to the radio frequency module 303 based on the reference frequency signal sent by the radio frequency module 303 to the waveform generation and sampling module. In the downlink part, a second FPGA chip 3043 and an AD chip 3041 digitize an intermediate frequency echo signal of the SAR system carrying the processing platform, and after DDC, filtering and 2-tap 1 processing, digital quadrature demodulation is performed to form echo acquisition data. According to the requirements of the SAR system, data compression can be performed by a compression processing module in the waveform generation and acquisition module 304, and the data compression is realized by a Block Adaptive Quantization (BAQ) algorithm.

In the embodiment of the application, the BAQ compression is realized by adopting the FPGA so as to improve the compression efficiency, and the compression process can be simplified into accumulation operation and table look-up operation. The BAQ compression employed by the waveform generating and acquiring module 304 specifically employs I, Q sample data distance direction 4bit (8: 4) BAQ compression per frame, and the flow steps of the BAQ compression are shown in fig. 10.

The compression module compresses I data or Q data input by 1 path according to 8: 4. And each data block is data with 512 sampling points, the average value of the data of the 512 sampling points of the data block is calculated, the calculated 7-bit value is used as the address of the lookup table with 7 bits higher, after the absolute value enters the cache array, the obtained 7-bit value is used as the address of the lookup table with 7 bits lower, and a 14-bit lookup table address is formed. Lookup table size, address: 14 bits wide and 8 bits wide. And outputting 3-bit data and the buffer output of the sign bit to form output data.

The specific flow steps of BAQ compression are as follows:

s101, separating sign bits and data bits of input data;

s102, solving the absolute value of each input datum according to the sign bit;

s103, carrying out blocking processing on the input data, and counting the amplitude of each block of data;

sending the absolute value of each block of data into a block accumulator array for absolute value accumulation;

s104, solving the mean value of each block of data;

the average value of the array data of the block accumulator is obtained;

s105, storing the absolute value of each input data into a cache array respectively, obtaining a query table address by combining the mean value of each block of data in the accumulator array, storing a quantized code value in a Read Only Memory (ROM), and obtaining a quantized code according to the query table address;

and S106, performing bit splicing, namely splicing the original data sign bit of each block of data with the quantization coding output bit of the query table to obtain finally compressed data, wherein the original data sign bit of each block of data is the sign of the highest sign bit of the block of data.

In some embodiments, since most of the rf module 303 circuits are analog rf circuits, there will be some electromagnetic interference to the digital circuits of its module, and in consideration of electromagnetic compatibility, the rf module 303 is located in a separate safety chamber, and communication with other modules is realized through connectors and cables.

The radio frequency module 303 adopts an independent cavity arrangement, so that the radio frequency module 303 is isolated from other modules, electromagnetic interference to digital circuits of other modules is reduced, communication with other functional modules is completed through connectors and cables, a safety cavity where the radio frequency module 303 is located can be independently and directly replaced, and the replacement of the radio frequency module 303 can be completed only by completing connection of the radio frequency module 303 with the power supply module 302, the main control module 301 and the waveform generating and collecting module 304 in a plugging mode.

The satellite-borne SAR system needs to be installed in and out of a cabin on the satellite platform 200, and the satellite-borne SAR load integrated processing platform realizes integrated system design through research on all electronic equipment in the SAR system cabin, unifies a network system of the electronic equipment in the satellite-borne SAR load cabin, determines function distribution and realizes electronic system integrated design.

The integrated design with high integration level is adopted, the equipment in the satellite SAR load cabin is only one single machine which is far lower than the quantity of the single machines in the similar SAR satellite cabin, especially, the system compatibility design verification is controlled at the single machine level, the test complexity of the whole satellite is greatly reduced, and the space requirement of the load on the satellite platform 200 is also greatly reduced.

The satellite-borne SAR integrated processing platform integrates various functions of central electronic equipment in the SAR system cabin, and realizes communication between single units of the SAR system through board-level interconnection. The main and standby machines of the power module 302 realize primary power conversion and power distribution of the SAR system by one circuit board; the main control module 301 has the same main and standby design, and the two circuit boards respectively realize the control functions of the main machine and the standby machine; the waveform generating and collecting module 304 has the same main-standby design, and the generation of intermediate frequency signals and data formation of the main machine and the standby machine are respectively realized by the two circuit boards; the five circuit boards are connected through a motherboard, the radio frequency module 303 is packaged independently and is isolated from other modules through a shell and installed in a single machine, so that physical isolation of an analog circuit and a digital circuit is realized, and the problem of electromagnetic compatibility in a processing platform is solved better.

When the radio frequency module 303 has a problem, the radio frequency module 303 can be directly replaced, software update is performed in a digital circuit, and generation of transmission signals with different frequencies and reception of echo signals can be achieved after a frequency source is changed more conveniently.

It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the apparatus described above may refer to corresponding processes in the method embodiments, and are not described in detail in this application. In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. The above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical division, and there may be other divisions in actual implementation, and for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or modules through some communication interfaces, and may be in an electrical, mechanical or other form.

The modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a platform server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The integrated processing platform for the satellite-borne SAR load is characterized by comprising: the high-integration-level integrated control system comprises a master control module, a radio frequency module, a waveform generating and collecting module, an inner bus module and an outer bus module which are arranged in an integrated manner;

2. The integrated processing platform for spaceborne SAR loads according to claim 1,

the radio frequency module is further used for sending the generated reference clock signal to the main control module;

3. The integrated processing platform for spaceborne SAR loads according to claim 2,

the main control module is specifically used for judging whether a working instruction received by the external bus module is directed to the processing platform;

if not, no processing is performed.

4. The integrated processing platform for spaceborne SAR loads according to claim 3,

the internal bus module specifically comprises a first internal bus and a second internal bus;

5. The integrated processing platform for the spaceborne SAR load according to claim 4, characterized in that the internal bus module specifically further comprises a third internal bus;

6. The integrated processing platform for spaceborne SAR loads according to claim 3,

a board connector is respectively arranged among the radio frequency module, the waveform generating and collecting module and the main control module;

7. The integrated processing platform for spaceborne SAR loads according to claim 2,

the processing platform also comprises a standby main control module;

8. The integrated processing platform for spaceborne SAR loads according to claim 7,

the processing platform also comprises a spare radio frequency module and a spare waveform generating and collecting module;

9. The integrated processing platform for spaceborne SAR loads according to claim 2, characterized in that the processing platform further comprises: the power supply module is integrated with the main control module, the radio frequency module, the waveform generating and collecting module, the inner bus module and the outer bus module in high integration level;

10. An on-board SAR system, characterized in that it comprises said processing platform of claims 1-9 and a front antenna, said front antenna performing imaging observation to the ground under the control of said processing platform.