RU2747240C1 - Space earth sensing system - Google Patents

Abstract

FIELD: space industry.

SUBSTANCE: invention relates to information space systems (SS) for integrated monitoring of the Earth. The SS contains compact and light spacecraft (SC) interacting with distributed ground-based complexes for control, reception and processing of images. A synthetic aperture C-band radar (based on an active phased antenna array – APAA), optoelectronic cameras of different frequency ranges, a signal receiver for the ship identification system AIS are installed on board the spacecraft. An adaptive high-speed (0.48 ... 1.5 Gbit / s) radio link for transmitting target information includes an APAA with a narrow beam in the X-band, and the modulation index is automatically selected depending on the estimated range to the receiving station.

EFFECT: technical result consists in expanding the information capabilities of the SS and increasing the efficiency of data exchange with the ground segment.

1 cl, 12 dwg

Description

Technology area

The claimed invention relates to the field of space technology, more specifically, to space systems (CS) of radar remote sensing of the Earth (ERS).

State of the art

In modern conditions of the development of digital information technologies in the remote sensing market, the most relevant changes for the better are the following basic quantitative indicators of the quality and performance of space systems:

- a significant reduction in the cost per square kilometer of space imagery;

- reducing the cost of manufacturing, launching and operating the ERS space system;

- reducing the cost of designing and manufacturing a spacecraft;

- Creation of a universal space platform for vehicles, which allows, on its basis, to manufacture vehicles with optical-electronic and radar payloads of various resolutions;

- reducing the mass and size characteristics of the spacecraft;

- the ability to carry out a group launch of ERS spacecraft;

- an increase in the spatial and linear resolution of images of space survey products without a significant increase in the mass of the spacecraft;

- increasing the frequency of surveying the territory of interest by increasing the maneuverability of the spacecraft (SC), as well as by quickly and efficiently creating a constellation of spacecraft;

- increasing the rate of transmission of target information to ground receiving points by using highly directional airborne antennas with electronic beam scanning and using dynamic signal modulation schemes;

- the use of a secondary optoelectronic payload as part of the spacecraft to increase the efficiency of processing the results of radar survey;

- reducing the cost of operating ground-based reception and control complexes by creating a network of universal combined in radio frequency bands (reception in the X-band, reception / transmission in the S-frequency band) container unattended stations, automatically controlled from a single center.

- the use of modern digital technologies for effective planning of the use of the target equipment of the ERS spacecraft in order to optimize the survey, taking into account the priorities, efficiency, as well as weather conditions and seasonality.

Various known solutions offer a solution to any of the listed aspects or a number of aspects. A detailed description of all known from the prior art solutions, such as the proposed invention, in the framework of this application does not seem appropriate.

At the same time, a decision should be indicated that can be taken as the closest analogue of the proposed invention in terms of purpose and a number of overlapping features.

Namely, there is a known ground-based special complex for receiving and processing images, disclosed in the patent document RU 2460136 C2, August 27, 2012 [1], which additionally includes an S-band transceiver path, which can be used to transmit control commands to the spacecraft ...

The known solution includes a ground complex for receiving and processing images, combined with a control complex.

The ground control complex in the solution known from [1] uses an antenna-rotary robotic complex operating in the S- and X-bands. The ground-based complex for receiving and processing images (and control) is built on the basis of automated workstations, a high-speed demodulator allows demodulation of signals with an arbitrary type of modulation.

The problem solved by the proposed invention is the simultaneous fulfillment of all of the above modern system requirements for ERS space complexes by implementing the proposed approaches to the construction of spacecraft and ground-based reception, processing and control complexes.

EFFECT: obtaining radar images with the best level of radiometric sensitivity.

Another technical result is the implementation of the direct reset mode (simultaneous shooting and resetting of the image to the receiving station) at speeds up to 1.5 Gbit / s without any mechanical guidance drives, only due to electronic scanning.

Another technical result is the use of dynamic modulation, which provides an increase in the volume of dumping of the raw stream when using a small-aperture antenna as part of the Earth receiving station.

Other technical results, the achievement of which is provided by the proposed invention, will be indicated in the following sections of the description, both explicitly and will follow for a specialist from the description of the design and functioning of the components of the complex.

Disclosure of invention

As an object of the invention, a space system for remote sensing of the Earth is considered, designed and manufactured taking into account the complex application of a number of technical and structural solutions that can significantly improve the main indicators of classical ERS systems.

According to the invention, in its detailed embodiment, a space-based Earth remote sensing system is provided, comprising:

- at least one spacecraft (SC), which is built on a load-bearing frame made of aluminum and / or carbon truss structures, and made with the possibility of placement under the head fairing of the launch vehicle;

- ground control complex (GCC);

- ground complex for receiving and processing images (NKPOI);

and containing in the payload:

- radar, with a synthetic aperture, built using an active phased antenna array (AFAR) of the C-frequency range;

- optoelectronic cameras of medium resolution in the visible and infrared frequency ranges;

- AIS automatic vessel identification signal receiver;

- equipment for transmitting target information, based on an active phased array with a narrow beam in the X-band, providing an adaptive high-speed radio link in the X-band with speed control from 480 Mbps to 1.5 Gbps, and the modulation index is automatically selected by the control system depending on the calculated relative range to the receiving station.

The radar payload, built using the C-band planar AFAR, makes it possible to obtain radar images with the best level of radiometric sensitivity.

The construction of the AFAR as a digital antenna array improves the overall reliability of the system and uses digital beamforming for transmission and reception.

This solution makes it possible to ensure the operability of the system with 2-3 working control devices (including one of the three central ones) with a slight decrease in functionality.

As a high-speed radio link for the transmission of target information, a solution based on an active phased array with a narrow beam in the X-frequency range is used.

This solution allows for the direct reset mode (simultaneous shooting and resetting the image to the receiving station) at speeds up to 1.5 Gbps without any mechanical guidance drives, only due to electronic scanning,

Also, the device uses dynamic modulation, and the modulation index is automatically selected by the control system depending on the calculated relative range to the receiving station. The volume of the raw stream discharge increases up to 2 times when using a small-aperture antenna as part of the Earth receiving station.

In a variant of the development of the invention, the NKU and NKPOI stations are located in unattended containers operating in an automatic mode and controlled from a single data processing center.

The invention provides solutions to many complex aspects. Therefore, for a clearer understanding of the essence of the invention, the corresponding results will be indicated below in the detailed description of the invention with a direct description of its essential features.

Implementation of the invention

For a more complete disclosure of the essence of the proposed invention is illustrated by the drawings, according to which are presented:

FIG. 1 - the composition of the remote sensing system.

FIG. 2 a, b - external view of the spacecraft structure.

FIG. 3 - view of the spacecraft in a transport configuration.

FIG. 4 a, b - view of the spacecraft in flight configuration.

FIG. 5-6 - dimensional drawing of the spacecraft in the transport configuration.

FIG. 7 - view of AFAR.

FIG. 8 - AFAR sublattice.

FIG. 9 - antenna panel.

FIG. 10 - high-speed radio link based on AFAR.

FIG. 11 - spacecraft placement during their group launch.

FIG. 12 a, b - a view of a ground control complex or a ground complex for receiving and processing images.

The implementation of the invention is based on the following provisions.

Preferably, the ERS CS includes at least one spacecraft, as well as a ground control complex, a ground complex for receiving and processing images, which can be conferred within one complex.

In addition, as shown in FIG. 1, the ERS CS may include more than one spacecraft (1), a combined stationary X and S-band antenna (2), a control and processing center (3), a mobile control complex (4), a mobile reception complex (5) ...

The combination of funds within one complex or their implementation by mobile is carried out depending on the conditions and goals of the tasks.

The spacecraft is built on a power frame made of carbon and / or aluminum truss structures. The invariability of the combinations of the dimensions of the structural elements makes it possible to provide the required strength. At the same time, at the same time, with the required rigidity, a low weight of the structure is provided.

The spacecraft is built using deployable solar panels and a deployable radar payload design.

The solar panels and the radar payload structure are actuated and locked in position for structural rigidity and minimal settling time after aiming maneuvers.

The spacecraft uses a radar payload built using a planar active phased antenna array (APAR) in the C-band (5250-5570 MHz, wavelength 5.54 cm). AFAR consists of three mechanical panels that serve to reduce the size of the spacecraft in the transport configuration (Fig. 7).

AFAR consists of 15 identical sublattices, each of which is an independent electronic device (Fig. 8). The three central sublattices are used to control the rest of the sublattices, collect data from all sublattices, filter and compress data, and store the survey results in a storage unit (BZU). This design makes it easy to scale the AFAR when calculating work in different orbits or to obtain radar images with a better level of radiometric sensitivity.

Thus, in FIG. 8 shows: antenna panel (6), combining devices in azimuth (7), a board of phase shifters and attenuators (7 channels) (8), signal separators / combiners in azimuth (7 per channel) (9), external digital interface (10 ), antenna panel controller (11), high power amplifier (7 channels).

In a particular case, structurally, each sublattice can consist of a control device - an FPGA with an 8-channel ADC / DAC, 6 identical antenna panels, a redundant power supply circuit, digital control and synchronization lines, digital signal lines. Antenna panels are an independent electronic device containing 7 lines of 16 transmitting-transmitting emitters (TRTs) in each, made using microstrip technology (Fig. 9). The step between the TIR is 23 mm, less than half the wavelength, which allows the level of the antenna side lobes to be reduced. Each antenna panel contains a frequency converter upward, a signal splitter into 7 channels, 7-channel controlled phase shifters, preamplifiers, attenuators, power amplifiers in the transmission path; circulators for switching electrical circuits from transmission to reception; 7-channel controlled phase shifters, low noise amplifiers, frequency converter downward, signal combiner in the receiving path. The amplifiers use gallium nitride transistors, which have a higher efficiency compared to gallium arsenide and silicon, greater radiation resistance, and a temperature range. The radar operates in a pulsed mode, with a duty cycle of 4 to 30, therefore, to eliminate voltage and current surges at the time of emission of pulses, supercapacitors of large capacity are used in the cascades of power amplifiers.

Antenna panels are combined in pairs into phase centers, in each sublattice there are three phase centers. Each phase center has its own ADC / DAC line. The FPGA used in the control device with an 8-channel ADC / DAC uses only 3 channels in the subarray for signals, 1 channel is allocated for the calibration circuit, the remaining 4 channels can be used to service the phase centers and the calibration circuit of the adjacent subarray. In this case, the FPGA in the adjacent subarray can be turned off and used in the "cold" backup mode, which significantly increases the reliability of the AFAR and the system as a whole.

To increase the resistance to radiation radiation, the electronic components mounted in a planar design on the rear side of the AFAR are protected by aluminum plates, the thickness of which is increased for the control device section.

In this version, the AFAR consists of 45 phase centers, each of which has its own digital and analog signal circuits. For additional reliability, it is possible to use all antenna panels in the sub-array as one phase center, which will require 15 signal lines. This solution makes it possible to ensure the operability of the system with 2-3 working control devices (including one of the three central ones) with a slight decrease in functionality.

The construction of the AFAR as a digital antenna array improves the overall reliability of the system and uses digital beamforming for transmission and reception. For example, obtaining three beams with different angles of deflection at reception is possible simultaneously with digital addition of signals from phase centers with different delays. In the classical implementation, in this case, it will be necessary to use three parallel analog lines and triple the number of ADCs.

An attitude control and stabilization system is provided in the spacecraft, which allows for both left-side and right-side imaging, which significantly increases the field of view, as well as the spacecraft rotation by 90 ° in yaw to ensure detailed imaging. The rotation of the spacecraft by 90 ° in yaw allows the use of scanning angles in azimuth of ± 25 ° without mechanical rotation of the spacecraft for tracking the survey area, while in the classical version in modern SARs the value of the scanning angle in azimuth is ± 2 °. This makes it possible to significantly increase the length of the synthesized aperture, improve the azimuth resolution, and use the azimuth signal accumulation to improve the radiometric sensitivity.

As a high-speed radio link for the transmission of target information, a solution based on an active phased array with a narrow beam in the X-frequency range is used. To increase the reliability and efficiency of the target information dumping, the spacecraft uses two grids installed on the left and right sides of the spacecraft relative to the longitudinal axis of the radar payload. This solution allows the direct reset mode (simultaneous shooting and resetting of the image to the receiving station) at speeds up to 1.5 Gbit / s without any mechanical guidance drives, only due to electronic scanning, which can be performed in a sector of ± 70 degrees from the normal in all directions both on the left side and on the right side of the spacecraft movement.

Also, the device uses dynamic modulation, and the modulation index is automatically selected by the control system depending on the calculated relative range to the receiving station, which provides an increase in the volume of the raw stream discharge up to 2 times when using a small-aperture antenna as part of the Earth receiving station. Due to the materials used in the structure of the power frame, the mass and size characteristics of the spacecraft, due to the above design, make it possible to place up to three vehicles under the fairing of the launch vehicle (for example, under the nose fairing of the Soyuz 2.1 launch vehicle) (Fig. 11) and perform a simultaneous group launch.

The ERS ground control complex (NKU) uses an antenna-rotary complex based on a robotic mechanism built according to a hexapod scheme with a minimum mirror diameter of 2.4 m ÷ 3.5 m and small-sized characteristics, operating in both S and X-bands.

The low-voltage switchboard uses a radio modem with a forward and reverse channel, which has high operational and technical parameters with minimal power consumption.

The ground-based complex for receiving and processing images (NKPOI) also uses an antenna-receiving device based on a robotic mechanism built according to a hexapod scheme with a minimum mirror diameter of 2.4 m ÷ 4.0 and small mass-dimensional characteristics, functions in both S and X-bands wavelengths.

In preferred versions, NKPOI is built on the basis of automated workstations (AWS) operating using open source software based on WINDOWS OS, as well as based on Astra Linux OS (optional).

The NKPOI is built using a demodulator operating in an adaptive mode in terms of modulation types depending on the elevation angle, providing speeds from 480 Mbit / s to 1.5 Gbit / s. This demodulator is equipped with an original de-mapper that allows demodulating signals with arbitrary types of modulation. The constellation setting can be done by the operator. The demodulator implements hardware decoding of error-correcting codes and removal of the transport protocol of the radio link at the rate of reception.

To increase the reliability and operating time, as well as to work under wind loads, the antenna systems are equipped with a radio-transparent shelter, as can be seen in Fig. 12 b.

To ensure the maximum total daily time of communication sessions with spacecraft, the earth stations of the NKU and the receiving stations of the NKPOI are geographically distributed / located in unattended containers operating in an automatic mode and controlled from a single center.

The GCC and NKPOI include a complex of specialized software (SSS), which can operate in two modes (automatic and manual). Automatic mode allows the ground complex to function with minimal operator intervention. Manual mode allows you to use each of the parts of the SPO complex separately.

The complex SPO NKU and NKPOI implements the following functions:

- planning of survey objects around the globe and bookmarking of the program on board the spacecraft with the selected package of tasks from the GCC (MCC);

- operator's voice notifications about system events and errors;

- formation, display and analysis of reports on the conducted communication sessions with complete telemetry of equipment and subsystems;

- real-time display of full telemetry of antenna receiving complexes (AIC) and demodulators (modems);

- collection and analysis of diagnostic data on the state of the NKPOI components before and during communication sessions;

- display of critical information about all the constituent parts of the NKPOI.

SPO NKU implements a flexible system for scheduling communication sessions with spacecraft, which supports a large number of antenna-receiving complexes (AIC). SPO NKU and NKPOI, for the effective work of operators, has a built-in system of electronic operational documentation in the form of pop-up messages with brief information and a link to a detailed description of the operator's actions.

Additionally, the SPO NKU and NKPOI has a built-in electronic training system for operators of automated workstations (AWP) NKPOI, which implements the following functions:

- familiarization and training in working with open source software of a certain workstation of NKPOI;

- carrying out tests to determine the assimilation of materials, qualifications and commissioning of AWP operators. ZS and NKPOI are built on the basis of remote control technology and transmission of the received information to the Data Processing Center through a wired or satellite communication channel of the Ku (Ka) -band.

Additionally, the SPO NKPOI has a built-in electronic system for processing received radar images, optical images and signals from the AIS (Automatic Identification System) system. When receiving images of the second processing level, neural network technologies are used, implemented on a hardware neural network module. The use of neural network technologies makes it possible to obtain, on a time scale close to real, products with thematic processing, such as: complex presentation of radar and optical images; automatic recognition of surface types, ice age, vessel recognition and detection of “dark” vessels with the AIS transmitter turned off.

In the stated decision, NKU and NKPOI are built on the principle of territorial distribution. From a single data processing center, the operation of a network of unattended container stations is automatically controlled.

The combined use of the above-described technical solutions makes it possible to achieve a significant improvement in the main characteristics with the achievement of the above technical results, and in addition, to significantly reduce the cost of the space system both at the manufacturing stage and at the operation stage.

Claims (10)

1. Space system for remote sensing of the Earth, including: - at least one spacecraft, which is built on a load-bearing frame made of aluminum and / or carbon truss structures, made with the possibility of placement under the head fairing of the launch vehicle; - ground control complex (GCC); - ground complex for receiving and processing images (NKPOI), and containing in the payload: - a synthetic aperture radar built using an active phased antenna array of the C-frequency range; - optoelectronic cameras of medium resolution in the visible and infrared frequency ranges; - AIS automatic vessel identification signal receiver; - equipment for transmitting target information, which is based on an active phased antenna array with a narrow beam in the X-band, providing an adaptive high-speed radio link in the X-band with speed control from 480 Mbit / s to 1.5 Gbit / s, and the modulation index is automatically selected control system depending on the calculated relative range to the receiving station. 2. The space system according to claim 1, characterized in that the NKU and NKPOI stations are located in unattended containers operating in an automatic mode and controlled from a single data processing center.

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