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VSAT (Very Small Aperture Terminal) is a satellite communications system that serves home and business users. A VSAT end user needs a box that interfaces between the user's computer and an outside antenna with a transceiver. The tranceiver receives or sends a signal to a satellite transponder in the sky.
A very small aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m.
Satellite internet equipment is made up of three main components: a geostationary satellite in space, a satellite dish mounted on your home and a modem that transmits internet signals from the dish to your computer. You obtain satellite internet through a satellite broadband provider.
Orbital VSAT is a Scorestreak Reward in Multiplayer available for unlock at level 42. It requires 1200 points in a match before using. Similar to the UAV, the Orbital VSAT shows both enemy position and direction on the team's mini-map in real time for 45 seconds.
A very small aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates range from 4 kbit/s up to 16 Mbit/s.
VSATs are used to transmit narrowband data (e.g., point-of-sale transactions using credit cards, polling or RFID data, or SCADA), or broadband data (for the provision of satellite Internet access to remote locations, VoIP or video).
Advantages / Benefits of VSAT Satellite Networks:
Access in Remote Locations: This has been the traditional strength of Satellite Networks. A Satellite in the Geo Synchronous orbit can cover around 33% of the earth’s surface and can provide connectivity to any region covered by it. A satellite can also focus on a particular high density region and multiple satellites can work together to provide global coverage. This is very useful for remote locations (rural areas, ships and coastal regions, hills, etc) where there is limited or no terrestrial connectivity.
Internet Access: A VSAT Network can provide Internet access in addition to the point to point WAN links. Its all set to create a next major wave in the consumer broadband industry with the launch of satellites operating in the Ka band offering very high throughput, especially in the non metro regions. ‘Always ON’ broadband Internet services are possible with VSAT networks.
Rapid deployment: Once the Satellite is put in to its orbit, the deployment at the customer premises can be done (usually in hours) if the equipment is available, with minimum training. And the deployment can be done in any region, irrespective of where it is located.
VPN: Satellites support encryption of all data transmitted between two sites or multiple sites, which make the creation of Virtual Private Networks (VPN) possible. This is one reason why the VSAT networks could find more acceptance in the corporate and Government/ Defense connectivity requirements.
QoS: VSAT Networks support QoS (Quality of Service) and Layer 2 prioritization policies to be applied across the WAN link which enables real time applications to be deployed across the network.
Mobile Access: Mobile access has been another traditional strength of a satellite network. This makes TV broadcasters (for example) make broadcasts from anywhere – even when they are on the move. Another possible application could be mobile Internet access, while on the move.
Bandwidth Allocation: It is possible to allocate/ restrict bandwidth based on individual applications – this could be a very useful feature for business communications, ensuring that critical business applications like ERP always have a certain dedicated bandwidth across the VSAT networks.
Scalable: VSAT networks can be easily and cost effectively be scaled to accommodate multiple locations across the globe. In fact, some of the largest customers of VSAT networks have as many as 10,000 sites on a single network!
Cost: Though the initial investment (service provider perspective) might be high in terms of the cost of satellites and putting them in the orbit, the running cost (end point terminals and on going subscription) is coming down rapidly – That’s why applications like Direct To Home (Cable TV) are broadcasted directly from satellites to homes at a reasonable cost to the subscriber.
Standards based: VSAT networks are standards based and support IP (Internet Protocol) and its variants through a protocol called IPoS (Internet Protocol over Satellite – TIA 1008). Since the developments are standards based, it enables the creation of a healthy ecosystem of terminal, hub and ancillary equipment manufacturers and hence new innovations and improvements are faster.
Reliable: Satellite Networks are very reliable (having up-times in the magnitude of 99.5% and above) and have been field tested for many years now. Mission critical applications like Bank ATM’s, Navy and Point of Sale appliances use VSAT!
Single Hop: Satellite transmissions are single hop (mostly) when compared to the multiple hops that the communications based on terrestrial networks need to take to reach to their destination. Some factors like router performance etc, depends on multiple service providers and hence end to end QoS may not be possible with terrestrial public networks.
One of the largest VSAT networks consist of more than 12,000 sites which are administered by Spacenet and the United States Postal Service. Some of the companies that utilize large VSAT networks include Walgreens Pharmacy, Wal-Mart, Taco Bell, Ford, General Motors, and many others. VSAT is used to transmit data such as sales orders and figures, service bulletins, international communications, and other types of data and communications.
Satellite providers that provide two way communications sometimes offer VSAT services. These are companies such as Bluestream, TM, Wild Blue, SatLynx, StarBand, and many others. Additionally, satellite providers that offer high speed broadband Internet to rural areas typically use VSAT technology as well.
Regardless if you are an individual using a VSAT system or an organization, most users desire to make their connection wireless. So the first question that always comes up is how to create a wireless connection with VSAT and whether or not you can use a conventional wireless router.
For example, some VSAT service providers offer connections that have a higher capacity or throughput and, in this case, it is necessary to choose a wireless router which is capable of handling a higher capacity connection. This is especially true for larger organizations that deploy VSAT communications systems.
On the other hand, if you are a residential user, the chances are that the VSAT service delivers a normal capacity connection. In this case, you can configure your home network with a typical router which is designed for residential use.
Highlighted Features :
Like any other technology, VSAT has its limitations too. Some of them include the extremely high initial cost needed for building and launching satellites in the Geo-Synchronous orbit, higher initial cost and recurring monthly costs for terminal equipments needed for providing Internet over broadband when compared to terrestrial DSL networks, Bit Error Rate is common for satellite based technologies, Rain Attenuation might affect the performance of VSAT communications under rainy conditions, latencies (>200 ms) are still higher than their terrestrial equivalent technologies (<100 ms), careful direction of subscriber side terminals and dish antennas are critical for proper working, trained man power is required for installation and maintenance, other competitive technologies (Internet Leased Lines, 3G/HSDPA/4G Cellular technologies etc) offer much higher bandwidth at a lower cost than what is possible by VSAT based networks, the antennas need to be fixed outside the offices or homes hence making them susceptible to damage or theft, the cost of VSAT modules for Network Routers/ Video Conferencing systems are quite high, etc.
VSAT system has the following characteristics:
1. It possesses the ability of digital treatment and transmission for multiple signals including voice, data and television conference. When transmitting voice, data and television conference, data compression technology has been widely adopted.
2. Flexible multi-access mode. The transmission line from primary station to remote small station is called outbound or outroute while the transmission link from small station to primary station is called inbound or inroute. The outbound information flow is discontinuous and the inbound information flow is intermittent, both of business volumes are asymmetric. Therefore, VSAT system adopts different multi-access continuation mode respectively in two transmission directions to realize asymmetric bidirectional transmission, which is the main difference between VSAT and other satellite communication system.
3. Network management system is more and more perfect. Because the information of small station is burst information, VSAT system must configure high intelligent network management system to monitor, control and manage operation status, channel allocation, business volume statistics of the overall network, which is one of the differences between VSAT and other satellite communication system.
4. Abundant network topological structure. Network topological structure of VSAT has three kinds which are star-shaped, meshed and composite. Star-shaped structure mainly applied in data communication must have primary station. Meshed structure mainly applied in voice communication doesn’t have primary station. And composite structure with more complex network management and channel control is available for large website comprehensively transferring multiple sets of information. The selection of network topological structure is mainly based on business demand.
5. VSAT device becomes gradually miniaturization and integration and the device price continues to drop, which makes VSAT system possess characteristics of easy installation, cheap price and convenient maintenance, etc.. The initial investment is quite large but the maintenance cost is cheaper.
6. Compared with other communication ways, VAST system possess the characteristic that communication link cost is not relevant to the distance, thus it is particularly applied to remote areas.
7. VSAT system expansion is easier. Use scope and transmission ability of VSAT can be expanded as long as the number of small station is increased and the bandwidth of uplink carrier and downlink carrier is adjusted according to the demand. The system’s expansion ability has much to do with equipment’s model selection; therefore, it should have certain predictability for development prospect of the system when designing the system.
We need to do the overall design firstly when setting up VSAT system. Then optimize system structure on the basis of user’s requirements. After that, provide exact content for each section which consists of system so as to calculate and demonstrate overall. Therefore, we can make VSAT system meet the preset quality requirements and network performance.
Application requirements analysis, technology overall design and project setup are included in overall system design. Application requirements analyses mainly study demonstration application, do conceptual design, and develop suitable technical overall design. Technology overall design includes the following aspects which are space satellite selection, earth station system demonstration, satellite link calculation, various of data optimization, network design. Project setup mainly make the regulations, and implement plans, methods, steps, open programs and appropriation budget.
A VSAT earth terminal is characterized by a much smaller antenna, typically less than 2m in diameter. Consequently, the unit cost is appreciably lower than that of the hub. The VSAT has both lower antenna gain and lower transmit power than a hub, with the power normally generated by semi-conductor devices of the type.
VSAT network is classified into three categories :
The first network is mainly based on data communication, beside this, this network can also offer fax and little voice operation.
The second network is mainly based on voice communication, this network mainly offer transition and exchange for public and special network, while it can offer interactive data services
The third network is mainly based on TV receiving, the receiving image and sound signal can be considered as the signal source of cable television, which is transmitted to user's home by cable distribution network.
Band selection : At present, band used by VSAT system have three categories which are 4/6 GHz at C-band, 12/14GHz at Ku-band, 20/30GHz at Ka-band. C-band has the advantage of mature technology and stable space transmission and the disadvantage that it can easily interfere with ground microwave of the same band and its location is limited greatly when used in cities. Ku-band has the advantage that it doesn’t have interference with ground microwave of the same band and it has smaller aperture and easy location, the disadvantage of unstable space transmission. Therefore, there is a need to keep enough link margin for Ku-band when designing the system. Ka-band is not applied broadly at present because of limited channel resource and complicated technology. C-band is generally available for voice transmission while Ku-band is generally available for data transmission. However, this is not absolute. Ku-band will become the main band in the later period of the 90s because of continuous increase of Ku-band repeater.
Selection of antenna aperture : Satellite antenna aperture is closely related to quality factor（G/T value）of earth station. G/T value and satellite power demand, i.e. equivalent rent bandwidth, show logarithmic linear relationship. In other words, the value of equivalent rent bandwidth increases with the narrowing of antenna aperture. Therefore, when selecting earth station aperture, it is not the smaller, the better. And earth station aperture should make a compromise between space overhead (equivalent rent bandwidth) and ground overhead (antenna aperture) to make system achieve optimum allocation.
VSAT system consists of satellite, hub and small earth stations. Hub is built near to the headquarters, has the function of main control. The antenna diameter and power is bigger than small station.
VSAT has the features of small antenna, compact structure, fully solid, low power consumption, low cost, low environment requirements, easy installation, wide cover range, flexible networking and independence. These features are suitable for requirements for many big enterprises and communication departments.
VSAT Structure :
Typical VSAT mainly consists of hub, satellite and remote VSATs. In general, VSAT adopts the structure of star network.
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 3.5m to 3.8m or C-band 7m to 13m with HPA, LNA, Up/Down Converter, Modem, data interface equipment...etc. Hub and main computers are often placed together, or hub is connected with the main computer by other ways, like earth or satellite.
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.
(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.
Antesky Science Technology Inc. is specially engaged in designing, manufacturing and installing satellite communication antennas and relevant servo equipments. We can offer a complete line of earth station antenna products and systems, such as Satellite communication antennas, Earth Station Antenna, Vsat antenna,TV receive only antennas, satellite news gathering Antennas, Flyaway antenna, control system and tracking system.
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