very small aperture terminal (satellite comm.) (VSAT)
Very Small Aperture Terminal (VSAT) is the name for a class of satellite-based communication systems and their services. It is a two-way communication from a satellite ground station via a geostationary or geosynchronous satellite for transmitting and receiving satellite signals via a parabolic antenna. The mirror of the parabolic antenna has a diameter of about 1 m.
VSAT applications are targeted at residential and business users who receive the VSAT signals via a transceiver. Data rates are relatively low, ranging from a few kilobits to up to 16 Mbps. The transmit and receive signals are transmitted to and received from the satellite orthogonally polarized. VSAT terminals use special and often proprietary modulation schemes, encryption techniques and coding algorithms. Communications typically involve the network layer using the IP protocol. The connected end users communicate via a point-to-point connection. The star point of the connection between two communication partners is the communication satellite.
The GEO satellites Copernicus, Eutelsat, Intelsat and others exclusively support stationary, fixed satellite transmissions with transmission speeds between 64 kbit/s and 45 Mbit/s in three connection topologies: fixed point-to-point connections, multipoint connections that can only receive signals, and interactive multipoint connections. In addition, geosynchronous LEO satellites can also be used, as voice communication is also possible via these.
VSAT supports up to 500 devices per central station and a maximum of 16,000 per network. VSAT systems are used by companies and institutions with widely dispersed locations to connect communications networks and provide Internet access.
VSAT systems are used in money transactions, payment services, RFID and SCADA, among others.