Providing telephone communications to remote moving objects using VSAT
Providing telephone communications to remote mobile objects is essential for many modern organizations. Despite the systematic increase in coverage of mobile networks of the main operators, there are still quite a lot of areas where there is no communication as such, and the only thing that can really guarantee communication is satellite technology. On the other hand, IP-telephony is increasingly prevailing over analog standards due to its cost, functionality and simpler structure.
One of the distinguishing features of IP-telephony is the use of technologies and data transfer formats using communication protocols standard for Ethernet technology. Such optimization allows, among other things, to reduce the volume of the data stream, and to use at the same time more communication channels. One of these channels, geographically more advantageous, is a satellite communication channel. Although at this stage of development the capacity of the satellite channel differs from geostationary lines, it can very well be used to provide the office or mobile facility with telephone landline communications. We described an example of such a solution in a material on our resource dedicated to land radio communications and ip-technologies.
Existing communication terminals based on satellite technologies BGAN, Open Port, Inmarsat-C, FleetBroadBand, although they have a sufficient communication channel, are not always convenient to operate due to limited functionality and reduced Internet access. To eliminate these problems, VSAT is used, providing speeds of up to 18 Mbps – enough to provide the necessary communication line for telephoning mobile objects.
Providing communications for moving objects
In the process of determining the number of subscribers at the facility, as well as assessing the amount of necessary traffic and functionality for each user, the necessary channel width is determined. If possible, the required data transfer speed is reduced to a minimum, and other services are connected, in addition to VSAT, for example, Iridium, Turaiya and Inmarsat telephony, as well as more “broadband” services from the same satellites of the Big Three operators. Although their services provide speeds of up to 512 Mbps when using various equipment, this may not be enough for a large facility to operate, especially if at least some of the subscribers need to provide Internet access. When optimizing the initial costs and large volumes of consumed traffic, VSAT connection is ultimately cheaper and more profitable than satellite channels from the same Big Three.
The construction of a communication system, including broadband Internet access and, on its basis, telephony of a remote office, mobile group, etc., thus, is preferable to implement on the basis of VSAT (Very Small Aperture Terminal). There is more than enough information about the technology of a small satellite earth station. One of its distinguishing features – its small dimensions – is beneficial for mobile objects, where most often vehicles, trains, ships and other objects with limited space act as carriers. In addition, mobile VSAT antennas, unlike terrestrial ones, are installed on a gyro-stabilized platform, with an establishment on it. Geostationary satellites broadcasting at preset frequencies find such an antenna automatically, and the platform’s electric drives themselves orient the antenna mirror to provide a better signal. Of course, such automation improves the quality of the system, but greatly increases the cost of the structure and limits its use in extreme conditions, when at low temperatures the platform needs to be insulated and strengthened by heating batteries.
Intellian-v60G-VSAT-Antenna-Credit-Andrew-Golden-Rushton-Gregory-Communications2.jpg VSAT system composition. The antenna system of the mobile VSAT itself consists of the antenna itself in the form of a convex mirror coated with a special coating. The transceiver is also assembled from a receiver with an amplifier (SSPA, BUC), a down converter (LNB) and a polarization selector (OMT). Each of them has its own technical characteristics and is selected depending on the tasks set by the customer, the necessary communication channel, the geographical location of the system and the type of medium.
The choice of antenna. The VSAT antenna itself is selected depending on the requirements, it is very important to choose the optimal system depending on all conditions and its cost. At the moment, VSAT mobile systems are quite expensive, in this regard, the help of technical specialists in the selection and selection of a mobile small satellite earth station can not only save money, but also get the necessary quality of communication, which is important, since the system itself is purchased for these goals.