VSAT Configuration
VSAT mainly consists of hub, satellite and remote VSATs. In general,
VSAT adopts the structure of star network.
(1) Hub
Main station which is also what we call
center station or hub, is main part of VSAT network. And it is the same to
normal earth station. Large antennas will be used in the hub, and the diameter
is often Ku-band
Typically, a network control center is set
in the hub or other places so as to monitor, manage, control and maintain the
full network. The network control center is used to monitor and manage the
operational status of the full network, like real-time monitoring, diagnosis
the working status, testing channel quality, responsible channel assignment,
statistics and billing for each small station and hub. The failure of main station
will affect the normal work of the overall network as the main station involves
the whole VSAT operation. Thus, the backup is set for all the devices, hub
often adopts modular structure, and the device adopts the way of high-speed
interconnect in order to be easy in reorganization.
(2)（VSAT）Small Station
VSAT small station consists of small
diameter antennas, outdoor unit and indoor unit. VSAT antennas have two types, one
is prime focus antenna and the other is off-set antenna. Prime focus antenna
has large diameter. However, off-set antenna has characteristics of small
diameter, good performance (high gain, low sidelobe), for its structure it's
not easy to collect snow, so off-set antennas are often be adopted. Outdoor
unit is mainly composed of CaAsFET solid amplifier, low-noise FET amplifier, upper/down
converter and corresponding monitoring circuit...etc. The whole unit can be
placed in a metal box and hang on the back of the reflector. Indoor unit is mainly
composed of modem, encoder and data interface equipment. Indoor and outdoor
unit are connected by coaxial cable, send low-IF signal and power supply. The whole
equipment has characteristics of compact structure, low-cost, full solid, easy
installation, low environment requirements, which can be connected with data
terminals (computer, data communication equipment, fax, Telex...etc), without ground
relay lines.
