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Expand your networks with VSAT
VSAT network types This is how a star data, TDM/TDMA VSAT network works using a hub station,
usually six metres or more in size and small VSAT antennas (between
75 centimetres and 2.4 metres). All the channels are shared and the
remote terminals are online, offering fast response times. Consequently,
TDM/TDMA systems are comparable with terrestrial X.25 or frame relay
connections. However, mesh networks which use capacity on a demand
assigned multiple access (DAMA) basis take a different approach. The
master control station merely acts as a controller and facilitator rather
than a hub through which traffic passes as in a star network. However,
these connections take a little time to set-up and thus, mesh/DAMA systems
are often equated to a terrestrial dial-up connection.
There are also mesh systems which use a TDMA access scheme where all of the terminals in a network receive and transmit to the same channel, selecting different time slots because each terminal is aware of what the others have reserved. In the past this type of system has been costly and therefore, reserved for large scale trunking applications, but, more recently, costs have come down considerably and now they can be cost competitive with SCPC/DAMA systems for thin route applications as well. Point-to-point SCPC (single channel per carrier) links are the satellite
equivalent of a terrestrial leased line connection. They are usually
set-up on a permanent, 24 hour basis and are thus more costly in satellite
capacity and less efficient if not used all the time. However, they
do support high bandwidths (typically from 9.6 kbps to 2 Mbps) and can
easily be used to carry data, voice and even video traffic. All other systems are usually a variation on one of the themes described
above, either in a star, mesh or hybrid (star and mesh) configuration.
Most of the TDM/TDMA manufacturers also offer a mesh product which can
be deployed in a hybrid-ised configuration, sharing common components
such as antennas and RF units, at a remote site. See VSAT customers and applications
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