AOCS IN SATELLITE COMMUNICATION PDF

The attitude and orbit control subsystem (AOCS) provides attitude information communications service equipment, and scientific instruments. Control is. An operating communications satellite system consists of Physical Structure. Attitude and Orbit Control System. (AOCS). Power System. Thermal Control. oriented framework for Attitude and Orbit Control System or AOCS of satellites. Understanding the case study requires some familiarity with the AOCS domain.

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During launching phase, the satellite spins when the small radial gas jets are operated. These three axes define the altitude of satellite. If there is a change in altitude of the satellite, then the angles between the respective axes will be changed.

Attitude and orbit control system AOCS. The satellites, which perform this kind of operation are called as de-spin. Before delivery for integration into the spacecraft, the AOCS system underwent several weeks of intensive testing, and subsequent System Validation Tests on the communicatiom satellite have confirmed its perfect operation.

Let X, Y and Z are another set of Cartesian axes.

Attitude and orbit control system(AOCS) | Satellite Communication

The second gas jet will be operated for same period of time, when the satellite reaches to the desired position. It is usually composed of one or more antennas, which receive and transmit over wide bandwidths at microwave frequencies, and a set of receivers and transmitters that amplify and retransmit the incoming signals.

We know that satellite may deviates from its orbit due to the gravitational forces from sun, moon and other planets. The maximum rotation speed of the reaction wheels is rpm. Likewise it will never point to within The receiver-transmitter units are known as transponders. The letter use is housekeeping, since these subsystems serve to support the communications system.

Reaction wheel courtesy of MMS. Altitude control subsystem takes care of the orientation of satellite in its respective orbit. An electric motor drives this communication system. In general, it can be rotated at 30 to rpm in order to produce a force, which is of gyroscopic type.

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This subsystem consists of rocket motors that are used to move the satellite back to the correct orbit when external forces cause it to drift off station and gas jets or inertial devices that control the attitude of the satellits.

The telemetry system sends data derived from many sensors on the satellite, which monitor the satellites health, via telemetry link to the controlling earth station. After this, the de-spin system operates in order to make the TTCM subsystem antennas point towards earth station.

Learn all you need in order to create a. Safellite orientation of a satellite in space is crucial, whether it be for telecommunications or Earth observation craft, or for astronomy missions like XMM-Newton.

The TTCM subsystem present at earth station monitors the position of satellite. OK Find out more about our cookie policy. The power is used by the communications system, mainly in its transmitters, aoxs also by all other electrical systems on the satellite.

Note that this is not a bright source avoidance cone, but driven by requirements on the spacecraft’s alignment with respect to the Sun to ensure sufficient energy supply and thermal stability. Power systems and rockets are present in this drum.

This site was designed with the. In this way, the AOC subsystem takes care of the satellite position in the right orbit and at right altitude during entire life span of the satellite in space.

These systems are partly on the satellite and partly at the controlling earth station. Due to this, communicaton spin axis gets stabilized and the satellite will point in the same direction. Satellites are of commuunication type swtellite called as spinners.

Satellite Communication AOC Subsystem

It is also used to control the antenna satlelite and communication system configuration to suit current traffic requirements and to operate switch on the satellite.

Altitude and Orbit Control AOC subsystem consists of rocket motors, which are capable of placing the satellite into the right orbit, whenever it is deviated from the respective orbit. Then, it will resolve that issue by bringing the satellite into the correct orbit.

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All communications satellite derive their electrical power from solar cells. AOC subsystem is helpful in commnication to make the antennas, which are of narrow beam type points towards earth.

Satellite Communication – AOC Subsystem

Based on telemetry data received from the satellite and orbital data obtained from the tracking system, the control system is used to correct the position and attitude of the satellite. ESA uses cookies satellkte track visits to our website only, no personal information is collected.

By continuing to use the site you are agreeing to our use of cookies. The design of the AOCS has been driven by a fail-safe approach.

The pointing accuracy of the 10 m long XMM-Newton is 0. However, should any serious anomaly occur, such as a prolonged loss of contact, XMM-Newton will automatically enter a survival mode and wait for direct control to be re-established from Earth. Two types of transponder in use: Most satellite antennas are designed to operate in a single frequency band, for example, C band or Ku band. So, the second gas jet will stop the motion of satellite in that axis direction. The direction of this motor will be opposite to the rotation of satellite body, so that the antennas point towards earth.

Spinner contains a drum, which is of cylindrical shape. These forces change cyclically over a hour period, since the satellite moves around the earth. A vital requirement of the XMM-Newton mission is that its delicate science detectors must not be damaged by luminous sources in the sky. This set of three axis provides the information about orientation of the satellite with respect to reference axes.

The communication subsystem is the major part of the satellite.