Satellite Internet is one of the ways to access the global information network. An indicator of successful work on the World Wide Web is the high speed of delivery of the requested information with the good quality of its presentation. Due to network congestion, this is not always possible when using modem connections based on telephone or even leased lines. An alternative to wired solutions was the technology using a satellite dish for the Internet.
How it works
Communication is based on the principles of digital satellite broadcasting of the DVB-S standard: from English Digital Video Broadcasting - Satellite (digital video broadcasting via satellite). In accordance with it, satellite system operators allocate one or more channels on the satellite to organize high-speed data delivery to users. Of the equipment you need a TV-Internet antenna, user terminal, converter and other devices.
Data transmission is carried out together with television and sound broadcasting signals and is carried out in the direction of a large number of users in the service area. At the same time, address (personal) delivery of the requested information from the Internet and streaming of information (films, music, news, etc.) to user groups by subscription are possible. Data is received by a satellite dish for the Internet and transmitted to a computer (TV).
Ways to build systems
Within the framework of this technology, two interactive ways of building systems have spread:
- combined (hybrid);
- bidirectional (symmetric).
The first (combined) uses 2 types of channels:
- ground (reverse) - to organize the request;
- satellite (direct) - to deliver information to users.
In the second method (bidirectional), only satellite channels are used to exchange information in the forward and reverse directions.
Combined method
With a combined method of constructing systems, the land channel is traditional. The user's computer is connected to the equipment of the local service provider (provider) through a wired modem connection or using cellular radio. The response information delivered via satellite is received on an individual installation consisting of a satellite dish for the Internet, a low-noise converter, a DVB-PCI card (with an interface for a personal computer) and the PC itself.
Symmetric way
With a bidirectional method of constructing the system, the user has a subscriber terminal for organizing a request and receiving response information via satellite channels. Terrestrial channels in this embodiment are not required, and the terminals can be located in the most remote corners, in transport. In the case of targeted data delivery, the return channel for the entire communication session remains on, which is necessary for the organization of confirmation of correctly received information. When streaming, the return channel after the request can be turned off, and the requested information is transmitted to the user's computer (in accordance with the identification code) without his participation. To request streaming information, you can use a mobile phone with the function of transmitting data on the Internet. In this case, again, you can not do without a satellite dish for the Internet and related equipment.
How to connect using the combined method
First, the subscriber enters into an agreement, pays for the traffic. Then, a satellite dish for the Internet is tuned in the direction of the satellite from which it is supposed to receive. Then you need to run the software and set the parameters of the satellite channel.
Through a modem or cellular network, it communicates with a local Internet provider, which, after checking access rights to the network, assigns the subscriber’s computer an Internet Protocol address (IP address) that is unique to this network. User data is transmitted to the server of the satellite service provider for encryption and sending a request to the Internet. The response parameters received from the network are combined into a digital stream with the data of other users and delivered via terrestrial channels to the transmitting satellite broadcasting station. At the station, the stream is converted into DVB-S format packets, noise-resistant coding, modulation and transmission of the radio signal to the satellite.
Data rate
A typical digital stream data rate is 45-50 Mbps. The data speed towards subscribers dynamically changes depending on their activity, the required quality of service, type of service, etc. The average data speed to one subscriber is 150-200 kbit / s, the maximum - about 2.5 Mbit / s.
Equipment
On the receiving side, with the help of an individual installation, signals are received from the satellite, and “identification” of the data intended for the user is made at the assigned identification addresses. The antenna amplifier of the Internet signal is usually offset, with a fixed or tunable method of pointing to the satellite. Its size is indicated during registration, for work in the Ki-band (10.7-12.75 GHz) is 0.6-1.2 m.
The antenna for the Internet modem is equipped with a converter, which is located in the focus of the antenna and is connected by cable to a DVB-PCI card. It is a simplified digital receiver, adapted for installation in a personal computer. The converter can be universal or dual, with one or two outputs, respectively. The second output is usually used to connect a digital receiver for independent viewing of TV programs by other users.
Most DVB-PCI cards produced are designed to process Internet data and watch TV on a personal computer. Some of them are equipped with a video encoder for the purpose of supplying television programs to a TV, as well as a conditional access card reader for installing a subscription card when receiving encoded programs.
How to connect using the bidirectional method
In a bidirectional satellite Internet access system, information is requested and delivered via satellite communication channels using a subscriber terminal. It consists of two blocks:
- external, designed for the transmission of high-frequency signals;
- internal (located in the room) - for digital processing of incoming and outgoing data.
The external unit is located in the focus area of the parabolic antenna for the Internet and is connected to the indoor unit by two coaxial cables. The terminal can operate in various frequency ranges allocated for satellite communications and broadcasting. Request and receipt of response data is organized through a central earth station and a satellite located in a geostationary orbit.
The station has access to the network and provides information exchange, control and management of all subscriber terminals located in the service area. In addition to data processing, the terminals are able to receive TV programs, sound broadcasting signals and establish telephone and fax communications.
Users
All terminals are equipped with typical network interfaces for working in local networks. The main consumers of the services provided by this technology are banks, government agencies, industrial companies, telecom operators.
An obstacle to the mass introduction of this technology in the CIS countries is the problem of issuing permits for the right to work in a satellite network, high subscription fees for the services provided, an expensive antenna for the Internet, the price of which ranges from 2000 (the simplest option) to 10,000 or more rubles. But the main barrier remains the high cost of subscriber terminals for private users (about 2-2.5 thousand conventional units). Therefore, our technology of satellite exchange of information using subscriber terminals has been used among corporate users.