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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Satellite Communication AOC Subsystem

In addition, a solar aspect angle within the range must be maintained at all times. If there is any change in satellite orbit, then it sends a signal regarding the correction to Orbit control subsystem.

Given XMM-Newton’s very specific orbit highly elliptical, irregular eclipse seasons, Sun avoidancethis required very complex hardwired logic within the unit.

ESA’s X-ray space observatory targets distant X-ray sources for akcs periods often exceeding ten hours and one of the key requirements of the satellite is its very high pointing accuracy and stability. A vital requirement of the XMM-Newton mission is that its delicate science detectors must not be damaged by luminous sources in the sky.

Communication subsystem is placed on top of the drum.

ESA Science & Technology: Engineering

For redundancy XMM-Newton carries a second star-tracker telescope. Attitude and orbit control system AOCS. If there is a change in altitude of the satellite, then the angles between the respective axes will be changed. The telemetry system sends data derived from many sensors on the satellite, which monitor the satellites satelpite, via telemetry link to the controlling earth station.

Before delivery for integration into the spacecraft, the AOCS system underwent several weeks of intensive testing, and subsequent System Validation Tests on the assembled satellite have confirmed its perfect operation. 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 satellite. This site was designed with the.

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It is responsible clmmunication the detection of anomalies of whatever origin and their correction. 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. 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.

Due to this, the spin axis gets stabilized and the satellite will point in the same direction. The receiver-transmitter units are known as transponders. Power systems and rockets are present in this drum. The letter use is housekeeping, since these on serve to support the communications system. From then on, the X-ray observatory’s life in space, for more than ten years, has been beating to the rhythm of its “electronic heart”.

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

The power is used sateolite the communications system, mainly in its transmitters, and also by all other electrical systems on the satellite. Let X, Y and Z are another set of Cartesian axes. The fully redundant AOCS represents some kg of electronics: AOC subsystem is helpful in order to make the antennas, sxtellite are of narrow beam type points towards earth. 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.

So, the second gas jet will stop the motion of satellite in that axis direction. These systems are partly on the satellite and partly at the controlling earth station. 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.

By continuing to use the site you are agreeing to our use of cookies. Spinner contains a drum, which is of cylindrical shape.

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Satellite Communication – AOC Subsystem

The maximum rotation speed of the reaction wheels is rpm. Altitude and Orbit Control AOC subsystem consists of rocket motors, which are capable of placing the satellite into communicahion right orbit, whenever it is deviated from the respective orbit. We know that satellite may deviates from its orbit due to the gravitational forces from sun, moon and other planets.

During launching phase, the satellite spins when the small radial gas jets are operated. In general, it can be rotated at 30 to rpm in order to produce a force, which is of gyroscopic type. The second gas jet will be operated for same period of time, when the satellite reaches to the desired position.

Likewise it will never point to within The design of the AOCS has been driven by a fail-safe approach. All eventual failures must be detected. The satellites, which perform this kind of operation are called as de-spin. An electric motor drives this communication system. The TTCM subsystem present at earth station sayellite the position of satellite.

Create your website today. In this method, each axis contains two gas jets.

This method is called as three-axis method. Orbit control subsystem is useful in order to bring the satellite into its correct orbit, whenever the satellite gets deviated from its orbit.

This set of three axis provides the information about orientation of the satellite with respect to commumication axes.

On the basis of data supplied by a star-tracker telescope, which recognises the different star formations in its field of view, the AOCS computers calculate the appropriate momentum of the reaction wheels for precision manoeuvring of the spacecraft during observations or commubication change the target.

Altitude control subsystem takes care of the orientation of satellite in its respective orbit.

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