RU2570833C1 - Method for low-orbit global satellite communication and system therefor - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to space communication and can be used when designing space operational communication systems for various purposes. A low-orbit global space information system consists of space and ground segments, includes subscriber spacecraft and is linked through telecommunication and information space to consumers on land, on water and in the air of a user segment. The space segment consists of N information nodes, which consist of main and associated spacecraft in the form of annular clusters linked by a local area network, wherein space information nodes are located in adjacent orbital planes, and the ground segment consists of a network of clusters which are interlinked directly or through the telecommunication and information space of a specific country with ground information nodes, each linked to space information nodes, which are also linked to all associated subscriber spacecraft.

EFFECT: faster operation, high noise-immunity and technological effectiveness of communication.

2 cl, 3 dwg

Description

The present invention relates to space communications and can be used in the design of space systems for operational communications for various purposes (IPC B64G 1/10, НВВ 7/185).

Since the beginning of the 90s, communication systems based on low-orbit spacecraft have become one of the new directions in the development of satellite communications. The low-orbit satellites LEO (LowEarthOrbit) include spacecraft, the orbits of which are in the range of 700-1500 km. A low-orbit constellation can contain from one to several dozen small satellites weighing up to 500 kg. To cover a large area of the Earth with communications, orbits are used, on which several spacecraft can be located, lying in different planes. For low-orbit satellite communications of the Russian Federation “Gonets-D1M”, the height of circular orbits is 1,500 km with an inclination of 82.5 °.

The increased interest in low-orbit satellite communications is explained by the possibility of providing personal communication services, including radiotelephone exchanges, using relatively cheap and small-sized satellite terminals. Low-orbit systems make it possible to ensure uninterrupted communication with terminals located anywhere on the Earth, and practically have no alternative when organizing communications in regions with an underdeveloped communications infrastructure and low population density.

One of the main advantages contributing to the development of low-orbit satellite communications systems is the biological factor. So, to meet the requirements of biological protection of a person from microwave radiation, the recommended level of continuous radiation power of a radiotelephone should be no more than 50 MW. Effective signal reception of such power, for example, by a geostationary satellite, is associated with a significant complication of the spacecraft, the deployment of large antennas and their exact positioning. For low-orbit satellite systems, the length of radio links is many times shorter and the problem of creating multi-beam antennas is less acute. These systems include, first of all, the Iridium and Globalslar systems created by foreign consortiums with the leading roles of such large manufacturing companies as Motorola / Lockheed and Oualcomm / Loral, respectively.

Low-orbit systems were considered by specialists at the dawn of the establishment of satellite communications, but until recently they were not widely used. There were a number of reasons, among which not the last place was occupied by a certain inertia of views and judgments, according to which the satellite “should be visible for a long time and continuously”, and it is best to “be motionless for the observer”, i.e. be in geostationary orbit.

True, over the past decade several low-orbit systems have been created, but for limited use, mainly related to the transmission of short and relatively rare messages (an example is the first draft of the Russian system “Gonets-D.” And only the tempting idea of global personal communication, based on modern technology, revived interest in low-orbit satellite systems.

A known communication system in a network with ground and space subscribers, including the space segment in the form of spacecraft in orbits for various purposes and the ground segment in the form of stations, which together form a communication network with ground and space subscribers (see RU No. 2070738, M. C. G08C 15/28, 1996).

This system is characterized by low communication efficiency and insufficient noise immunity.

The closest analogue, selected as a prototype of the claimed invention, is a two-level satellite communication system, including space and ground segments, respectively containing low-orbit constellations of satellites located in circular orbits in three evenly spaced planes and constellations of satellites located in mid-altitude elliptical orbits in two orbital planes. Both space groups are equipped with inter-satellite communications. The ground segment includes a control complex, a consumer complex and terrestrial communication channels with a public network, mobile and stationary subscriber stations, coordinating communication stations located at the calculated points of the Earth and connected to terrestrial repeaters, see RU No. 98659, cl. HB04 7/185, 2006

This system is characterized by low responsiveness, noise immunity and adaptability of message transmission due to the large number of communication channels when servicing space subscribers (for example, remote sensing spacecraft (ERS)) with ground-based control means.

The problem solved by the invention is to increase the efficiency, noise immunity and adaptability of message transmission by reducing the number of communication channels KA-Earth, especially when servicing comic subscribers.

The solution to this problem is ensured by using the global low-orbit satellite communication method.

The essence of this method is illustrated in FIG. 1 and is as follows.

1. The space segment of the system is divided into rings of space information nodes - uniformly displaced orbital planes. To ensure global connectivity and real-time interaction, it is advisable to introduce a displacement of the orbital planes of 30 ° one relative to the other in the longitude of the ascending node (optimally six space rings - planes).

2. Each ring includes N space information nodes (KIUs) uniformly spaced in orbit (optimally 8 nodes in each ring to ensure global communications and real-time interaction) and shifted relatively identical space information nodes located in adjacent rings on half an arc - the distance between adjacent nodes in one ring.

3. In each of these nodes include a low-orbit spacecraft (SCA) interacting via local networks with the subscriber systems of the user system located in the zone of its radio visibility (for example, a remote sensing spacecraft with orbits of 200-800 km), which are a cluster.

4. The ground segment is formed from a network of ground-based information nodes connected directly to each other or via telecommunication or information space, each of which is connected via a space radio channel to the main objects (NSC) of the space information nodes of each of the rings of the space segment of the system.

Since spacecraft-subscribers of clusters interact only with the main low-orbit spacecraft of their space information node, the radio channels of ground-based control facilities for spacecraft-subscribers are excluded, which increases technological effectiveness and ensures global control of spacecraft-subscribers, including outside the territory of Russia by using the low-orbit communication spacecraft as space relays with an inter-satellite communication line. At the same time, noise immunity and efficiency of information interaction are significantly increased up to the time scale close to real.

Thus, due to the exclusion of radio channels of interaction between spacecraft subscribers of the system with ground-based control systems, the manufacturability, responsiveness and noise immunity of the system are increased, and global control of spacecraft subscribers through spacecraft of low-orbit communication via the inter-satellite communication line is ensured.

In FIG. 2 presents a satellite system for implementing the proposed method, where:

1. The space segment of the system.

2. The ring (plane) of space information nodes.

3. Space information node.

4. Low-orbit primary communication spacecraft.

5. A spacecraft - a subscriber (for example, a remote sensing spacecraft).

6. Cluster of spacecraft subscribers.

7. The ground segment of the system.

8. A network of ground information nodes.

9. Telecommunication and information space.

10. Ground information node.

11. DBK-KIS of the main low-orbit communication spacecraft.

12. Modem BRK-KIS low-orbit spacecraft communications.

13. BRTK KA-subscriber.

14. The modem BRTC KA-subscriber.

15. User segment of the system.

The system consists of space 1, ground 7 and user 15 segments. Space segment 1 consists of N interconnected inter-satellite communication lines (MLS) of space information nodes (KIU), for example, of eight nodes located in each of the displaced orbital planes, for example, six orbital planes (spaced one relative to the other by 30 ° in longitude ascending node). Each KIU consists of a main low-orbit (SCA) 4 and associated spacecraft-subscribers (KAA) 5, forming clusters 6 with their own circular orbits. The main NKA 4 and the associated KAA 5 - in KIU 3 are removed from each other up to 700 ÷ 2000 km. In one orbital plane of a satellite 4, there can be several, for example, eight, clusters 6. CAA clustered in a cluster are connected to the satellite by local inter-satellite communication networks.

The ground segment (NS) 7 consists of a network of ground-based information nodes (NRUs) connected directly or via telecommunication and information space 9 of a country (for example, Russia) 8. These NRUs are connected via space channels to the main NKA 4, as well as to ground or radio channels of communication - with consumers of the user segment 15 of the system. Moreover, NKA 4, in turn, are associated with all KAA subscribers 5.

During the operation of the system, subscribers are connected via the NRU and KIU networks. The interaction of the NRU system is carried out only with the main spacecraft 4 of each KIU. Consumers of the user segment 15 system on land, on water and in the air through telecommunications and information space have access to receive target information to all the main spacecraft 4 KIU 3 of the space segment of system 1, which, in turn, is associated with KAA subscribers (5), due to which the number of Earth-KA channels for spacecraft-subscriber management is significantly reduced and the necessary efficiency, noise immunity and adaptability of message transmission are ensured.

In FIG. Figure 3 shows a variant of the structural diagram of the on-board radio complex (BRTC) with feeder channels in the range 0.3-0.4 GHz and subscriber channels in the range 2.2-2.6 GHz, on-board relay complex (DBK) with an inter-satellite communication line (MLS) ) in the range of 2.2-2.6 GHz and the on-board complex of the command and measurement system (BKIS) with a control channel in the range of 0.3-0.4 GHz.

The functioning of the receiving and transmitting devices is provided by the antenna-feeder system (APS), which is part of the spacecraft.

Receiving and transmitting devices operate under the control of a distributed computer network - an on-board computer complex. The on-board computer complex (BVK) consists of the main computing module (OBM), peripheral computing modules (VM) and on-board software (software).

For servicing spacecraft subscribers in the range of 0.3 / 0.4 GHz, a 7-beam conformal grating is used for reception and transmission. The outputs of 10 transmitters are connected to a high-frequency (RF) switch that connects any of the transmitters to the input of one of the 7 diplexers.

The connection scheme of 10 receivers to 7 outputs of diplexers is similar. Thus, 3 “cold” receivers and 3 “cold" transmitters through a switch can replace any, respectively, receiver or transmitter that has failed in any of the beams.

The choice of 3 working transmitters from 7 is determined by the on-board computer complex.

The feeder channel in the 2.2 / 2.6 GHz band uses a 7-beam conformal array. 2 transceivers are connected to certain beams according to the instructions of the onboard computer complex (IAC), depending on the location of the communicating earth stations (AP).

All receiving paths are constructed identically: after the linear amplifying path, digital signal processing is performed: demodulation, decoding and decompression. The intermediate frequency (IF) path of the receiving device in the range of 0.3-0.4 GHz has a band of 1 MHz. A multi-channel digital demodulator receives a signal with a frequency of 10 MHz. A digital multi-channel demodulator simultaneously processes a group signal containing several independent GMSK signals.

The IF path of the receiver in the 2.6 GHz band has a band of 1.2 MHz.

Transmission paths are also constructed identically. Signal compaction and shaping is done by a digital modulator.

Modulators and demodulators (modems) are implemented on the basis of signal processors operating under the control of on-board software according to the “hot” - “cold” scheme.

A modem is a device used in communication systems for physically interfacing an information signal with its distribution medium, where it cannot exist without adaptation. The modulator in the modem modulates the carrier signal during data transmission, that is, changes its characteristics in accordance with changes in the input information signal, the demodulator performs the reverse process when receiving data from the communication channel. The modem serves as the terminal equipment of the communication line. The formation of data for the transmission and processing of received data is carried out by the so-called terminal equipment (a personal computer may also play its role).

The on-board computer complex functionally combines:

- The main computing module (OVM) with cold reserve;

- 7 peripheral computing modules of the spacecraft subscriber channel (VM-A) in the range 0.3 / 0.4 GHz each with a cold reserve;

- 1 peripheral computing module of the spacecraft control channel (VM-KU) of the range 0.3 / 0.4 GHz with cold reserve;

- 2 peripheral computing modules of the feeder channel (VM-F) of the 2.2 / 2.6 GHz band with cold reserve;

- 2 peripheral computing modules for inter-satellite channels (VM-M) in the 2.2 / 2.6 GHz band with cold standby.

All computing modules exchange information using a system channel that provides traffic for all simultaneously working trunks.

OVM has the ability to control the power-up of peripheral computing modules using the control channel and load the work program into them.

Programs loaded into peripheral computing modules are selected from the EEPROM, which is part of the OBM (according to the "hot - cold" scheme), or from the EEPROM of the corresponding VMs (according to the "hot - cold" scheme). Target information received via relay channels operating as part of DBK is stored in two memory devices for storing target information (memory CI) according to the hot-cold scheme.

Software peripheral computing modules have the ability to control synthesizers of receiving devices.

The OBM and VM of the subscriber channels of the spacecraft interacts using special interfaces with transmitting devices. The OBM interacts with a telemetry information collection device (US TMI), an emergency-time device (AVU), an on-board control complex (BKU) as part of command issuing devices for facility systems and BRTK, BRK and BKIS configuration control devices.

AVU with timers of “control intervals” is reserved according to the three “hot” scheme with majorization of executive functions according to the “two out of three” scheme.

Three switches of the RF path of the transmitting antenna, which perform the functions of switching the output signals of the microwave primary and backup sets of amplifiers of frequency ranges.

Two reference frequency generators ("frequency standards" - ECH) with a propagation device (UR), operating as part of the BRTK, BRK and BKIS according to the "hot-cold" scheme.

One primary power switching device (PPC). Diplexer and transceiver antenna of the control channel in the frequency range of 0.3 / 0.4 GHz.

The software package BRTK, DBK and BKIS.

The system implements all the operations of the proposed method and ensures the achievement of the goal of the invention.

Claims (2)

1. A method for global low-orbit satellite communication with space subscribers of a user system in a low-orbit information system, characterized in that the space segment of the system is formed of six rings of space information nodes, adjacent orbital planes of which are uniformly offset 30 ° in longitude of the ascending node, with each of these rings form eight space information nodes uniformly spaced in orbit and shifted one relative to the other in adjacent planes on the polo the fault of the arc-distance between adjacent spacecraft in the same plane, and in each of the mentioned nodes there is a low-orbit communication spacecraft configured to interact through local networks with spacecraft-subscribers of the user system, which are clusters located in the zone of its radio visibility, and a system segment is formed from a network of interconnected directly or via telecommunication or information space terrestrial information nodes, each of which is configured to communicate via the space radio channel with the main objects of the space information nodes of the low-orbit communication of each of the rings of the space segment of the system. 2. The system that implements the method according to p. 1, including space and ground segments, characterized in that the space segment consists of six orbital rings equally spaced in the orbital planes, each of which includes eight space information nodes, consisting of interconnected via inter-satellite communication lines via modems of onboard relay complexes of a low-orbit communications spacecraft and subscriber spacecraft constituting a cluster of a node, low-orbit spacecraft in each node they are not connected via modems of the airborne relay complex to each other and to the network of ground-based information nodes that are part of the ground segment, connected by the telecommunication and information space network to users of the user segment.

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