What Are the Components of a VSAT System?

What are the components of a VSAT system? The main equipment includes the following seven systems.

1. Position and attitude control system of VSAT system

In theory, the position of a geostationary satellite is stationary relative to the earth, but in practice it is not often able to maintain this relative stationary state. This is because the Earth is not really a spherical shape, so the relative velocity of the satellites to the Earth is affected.

At the same time, when the radiation pressure of the sun and the moon changes strongly, the relative position of the satellite to the earth is often destroyed due to the interference to the satellite caused by them. These can cause the satellite to drift out of orbit, making communication impossible. One of the tasks of the orbit control system is to be responsible for maintaining and controlling one's position on the orbit. It is not enough to keep the satellite in its designated position in orbit, it must also have a correct attitude in that position. Because the beam of the directional antenna on the satellite must always point to the center of the earth or the center of the coverage area.

Since the directional beam is only a dozen degrees or narrower, the beam pointing is greatly affected by the change of the satellite attitude. In addition, the satellite is 36,000KM away from the earth's surface, and the attitude difference is very small, which will cause the antenna to point to a thousand miles. Furthermore, the surface of the solar cell must constantly face the sun, all of which require control of the satellite attitude.

2. Antenna system of VSAT system

The antenna system of the communication satellite includes a communication antenna and a telemetry command antenna. Two kinds of antennas are required to be small in size, light in weight, high in reliability, long in life, high in gain, and always point the beam to the earth, respectively using derotation antennas and omnidirectional antennas.

3. Transponder system of VSAT system

The space transponder system is the main body of the communication satellite. In fact, it is a high-sensitivity wideband transceiver. The intelligence is to forward the wireless signal with minimal additional noise and distortion and with the highest possible amplification.

4. Telemetry command system of VSAT system

The main task of the telemetry command system is to tell the satellite monitoring and control station on the ground the working conditions of the equipment on the satellite as it is, and at the same time faithfully receive and execute the command signal sent by the ground monitoring and control station.

5. Power system of VSAT system

The power supply of modern communication satellites uses both solar cells and chemical cells. The power supply system is required to be small in size, light in weight, high in efficiency and long in life.

6. Temperature control system of VSAT system

The temperature control system can keep the internal and surface temperature of the satellite within the allowable range, otherwise it will affect the performance and life of the electronic equipment on the satellite, and even malfunction. In addition, when the temperature difference on the satellite shell or the antenna is too large, deformation often occurs, which will have a negative impact on the direction of the antenna, the accuracy of the sensor, and the directionality of the nozzle.

7. Orbiting and propulsion system of VSAT system

The orbit control system of the geostationary satellite is mainly composed of two jet propulsion systems, axial and lateral. The axial nozzle is used to control the drift of the satellite in the latitude direction, and the lateral nozzle is used to control the drift of the satellite in the longitude direction due to the change of the orbiting speed of the satellite. The nozzle is composed of a small gas (a gaseous fuel) rocket, and its ignition timing and the duration of the gas are controlled by control signals sent to the satellite from the ground monitoring and control station.

Another function of the propulsion system is to control the attitude of the satellite by means of spin stabilization, gravity gradient stabilization and magnetic stabilization.