VSAT (Very Small Aperture Terminal) describes a small terminal that can be used for two-way communications via satellite. VSAT networks offer value-added satellite-based services capable of supporting the Internet, data, video, LAN, voice/fax communications, and can provide powerful private and public network communication solutions. They are becoming increasingly popular, as VSATs are a single, flexible communications platform that can be installed quickly and cost efficiently to provide telecoms solutions for consumers, governments and corporations.
The benefits of VSAT technology are being realized in many sectors, both private and public. From banks to administrations, schools, hospitals, and rural telecommunications, VSATs are being seized upon to elevate economic, educational, and health standards.
VSATs have been in use for more than 20 years and, with already millions installed all over the world, VSATs are a mature and proven technology.
A point-to-point satellite link provides a direct link between two sites, which are located within the same satellite footprint.
These networks easily support voice, video, and data transmissions using a standard data/voice multiplexer, an SCPC satellite modem and a VSAT terminal at every site. It is a very simple approach for point-to-point networks as communications takes place only between the two sites. This type of connection is very often used to provide standard internet services through our teleport.
Star Network
A Star Network is typically used for a Main Office - Branch Office scenario, where all the branch offices only communicate with the Main Office - not with other remotes.
An interbranch office communication is possible, but the signal (data/voice) runs from the branch remote site to the central site - and then to the other branch remote site. Typical applications for a Star-Network are Corporate Networks with a headquarter and remote offices.
Mesh Network
A Mesh Network topology allows several remote sites (VSATs) to communicate with each other via a single link through the satellite. The "single hop" nature of this network design leads to a minimal time delay between signal transmission and reception.
Historically, mesh networks have been an expensive application to provide dedicated satellite communications. However, modulation and compression improvements have helped to make this service more cost efficient.
Mesh technology is best used for a group of VSAT systems which require real time applications (Voice, Video) between every site without the latency created by a double satellite hop with communications via a teleport.
C-Band is a part of the electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz.
C-band is primarily used for satellite communications, generally with downlink 3.7–4.2 GHz, uplink 5.9–6.4 GHz, usually 24 36-MHz transponders on board a satellite. Most C band satellites use linear polarization, while a handful (particularly older Intelsat satellites) use circular polarization.
Typical antenna sizes on C-band capable systems for home reception in North America range from 7.5 to 12 feet (2 to 3.5 m). In other regions of the world, such as Europe and parts of Asia, considerably smaller antennas can be used due to high-powered satellites in this band and more distance between satellites in the orbital arc (compared to the two-degree spacing common over North America).
C-Band usage is less common in Europe, where KU Band has traditionally dominated. In many parts of the world, C-Band is often used to cover a very broad area, for example all of Africa or China. Indeed, many C-Band satellites have "global" beams with gigantic coverage areas. C-Band is considered to be more resistant towards rain fade.
KU Band is a part of the electromagnetic spectrum in the microwave range of frequencies ranging from 12 to 18 GHz.
KU Band is primarily used for satellite communications, particularly for satellite backhauls from remote locations back to a television network's studio for editing and broadcasting.
KU band is split into multiple segments that vary by geographical region by the International Telecommunication Union (ITU).
Several highly used segments in the Americas (ITU Region 2) are:
The 11.7 to 12.2 GHz band is allocated to the FSS (fixed satellite service, uplink 14.0 to 14.5 GHz). There are more than 22 FSS Ku-band satellites orbiting over North America, each carrying 12 to 24 transponders, 20 to 120 watts per transponder, and requiring a 0.8-m to 1.5-m antenna for clear reception. The 12.2 to 12.7 GHz segment is allocated to the BSS (broadcasting satellite service). BSS/DBS direct broadcast satellites normally carry 16 to 32 transponders of 27 MHz bandwidth running at 100 to 240 watts of power, allowing the use of receiver antennas as small as 18 inches (450 mm).
Several highly used segments in Europe and Africa (ITU Region 1) are:
The 11.45 to 11.7 and 12.5 to 12.75 GHz bands are allocated to the FSS (fixed satellite service, uplink 14.0 to 14.5 GHz).
The 11.7 to 12.5 GHz segment is allocated to the BSS (broadcasting satellite service).
Other ITU allocations have been made within the Ku band to the Fixed Service (microwave towers), Radio Astronomy Service, Space Research Service, Mobile Service, Mobile Satellite Service, Radiolocation Service (radar), and Radionavigation. However, not all of these services are actually operating in this band and others are only minor users. NBC was the first television network to uplink a majority of its affiliate feeds via Ku-band in 1983.
Ku Band has become the standard in V-SAT Broadband Internet applications. It is, if well designed, not affected by interferences or rainfalls.
Within the last years the price for the equipment has dropped to a level which allows satellite broadband operators to offer products and services at affordable prices.
The Ka band is a portion of the K band of the microwave band of the electromagnetic spectrum.
Ka-band roughly ranges from 18 to 40 GHz. The 20/30 GHz band is used in communications satellites, downlink 18.3–18.8 GHz and 19.7–20.2 GHz. The term Ka-band is frequently used to refer to the recommended operating frequencies of WR-28 rectangular waveguide, which is 26.5 to 40.0 GHz.
Ka band in future will allow a broader application field in the V-SAT Industry. At the moment only very few capacity possibilities are available in Ka Band.
Those commercial projects available suffer from the global warming and the resulting climatic change.
You will ask why ? Very simple: The increase of rain and stong weather conditions terrible affect service stabilities in KA band. Due to stronger and longer bad weather periods outages of services in KA Band have dramatically increased in the last 3 years.
However its quite exciting to get more bandwith out of a smaller required space segment - KA band related services still will have to proof that they really will play a major role in futures satellite communication business.
Many of our customers, especially those located in Africa, ask us about the difference between C- and KU band.
Satellite communication systems are subject to international agreements and regualtions. The International Telecommunication Union (ITU) regulates frequency use and defines "bands"
The following bands are commonly used:
- C-band was the first band to be used for satellite communication systems. However, when the band became overloaded (due to the same frequency being used by terrestrial microwave links) satellites were built for the next available frequency band, the Ku-band. Today C-Band also gets disturbed by wirless radio links in particular uncontrolled spreading in Africa. Interferrances can get reduced by cost intensive microwave filters level421 generally recommends each customer who plans to use C-Band.
- Ku-band is typically used for broadcasting and 2-way Internet connections.
C-band:
The C-band frequency range has one significant problem. It is the frequency region assigned to terrestrial microwave radio communication systems. There are an emerging number of these microwave systems located all over the world and they carry a large volume of commercial communications. Consequently, the VSAT locations needed to be restricted in order to prevent interference with the terrestrial microwave communication systems. As mobile phones get used more and more in countries all over Africa as well, the use of C-Band in future will possibly certainly rather decrease than increase. At the current point of time - C Band nevertheless is widely used. In particular as KU band capacity over some regions is quite limited.
Ku-band:
The Ku-band frequency range is allocated to be exclusively used by satellite communication systems, thereby eliminating the problem of interference with microwave systems. Due to higher power levels at new satellites Ku-band allows for significantly smaller earth station antennas and RF units to be installed at the VSAT location.
The myth:
At the inception of satellite communications in Africa, C-band was the only option. It has been the long held belief that Ku-band could not be deployed in Africa due to the torrential rains associated with the continent. However, with the technology progress in the satellite industry (invention of ACM gain controlled systems), and the fortune that more powerful satellites now exist. This thereby eliminates the impact of heavy showers. Its all a matter of correct design and proper equipment to make Ku band same stable than C Band to rain factor influence.
This allows VSATplus FZCO to offer up-time guarantees ranging from 99.70% - 99.95% using the Ku-band frequencies. Same we do guaranty for C-Band frequencies.
Which solution to choose depends today from commercial and less from technical factors, as no matter what frequency band used - both technologies supply internet services at acceptable quality.
Commercially it is fact that hardware for C Band is significantly more expensive while the capacity is cheaper. So customers with large bandwith requirements preferrably choose this technology.
KU Band on the other hand operates with small antennas and less expensive equipment, while the capacity price is higher than C Band.
C-Band
Downlink: 3.7 – 4.2 GHz
Uplink: 5.9 – 6.4 GHz
Advantages:
Less disturbance from heavy rain fade
Cheaper Bandwith
Disadvantages:
Needs a larger satellite dish (diameters of minimum 2-3m)
Powerful (=expensive) RF unit
More expensive hardware
Possible Interference from microwave links
Ku Band
Downlink: 11.7 – 12.2 GHz
Uplink: 14.0 – 14.5 GHz
Advantages:
No interference from microwave links and other technologies
Operates with a smaller satellite dish (diameters from 0.9m) -> cheaper and more easy installation
Needs less power -> cheaper RF unit
Disadvantages:
More expensive capacity
Sensitive to heavy rain fade (significant attenuation of the signal) / possibly can be managed by appropriate dish size or transmitter power.
When booking a shared Internet Service via Satellite the contention rate should inform you about the numbers of users you are sharing the subscribed bandwidth with. E.g. with a 1:10 ratio you share the bandwidth with 9 other users.
We are one of the few providers who guarantee the ratios and do not overbook them. And we guarantee also committed CIR bandwidth - which is the minimum available bandwidth also in peak times.
CIR > Committed Information Rate
Committed Information Rate (CIR) is based on an ITU-T Standard. CIR is the minimum available bandwidth guaranteed by a provider under normal network conditions. All Services include CIR and this provides our clients an outstanding performance.
Time Division Multiple Access is a communication technology which allows the set up of shared star-type two-way satellite IP networks. The remote stations are connected by satellite (satellite-to-satellite links) with the central hub earth station which manages incoming and outgoing traffic influx.
IDirect has developed a proprietary unique technology of its kind which permits to determine the best access method to transmission equipment. Same like DVB-RCS it uses TDM protocol (Time Division Multiple) for outbound service and Direct TDMA protocol for inbound channels. It is an ideal choice for establishing geographical networks aimed to support management applications, video-conference, Voice over IP, web applications and non real time applications in general.
SCPC - Single Channel Per Carrier
Single Channel Per Carrier (SCPC) allows the set up of two-way point-to-point satellite networks for transmission of video, voice and data. The dedicated, not shared satellite bandwidth is allocated exclusively to two satellite stations which establish the network with bandwidth capacity from 64 Kbps up to 2 Mbps or more from point A to point B.
In the last 5 years technology leading companies, like COMTECH EF Data have developed dynamic SCPC which allows dynamic re-sizing of satellite carriers on the fly and according to the demand. The switching works packet loss free.
We mainly use the COMTECH EF Date product line SCPC links. We prefer dynamic SCPC as it is a much more satellite bandwidth efficient technology compared to classic SCPC.
FleetBroadband is a maritime global satellite internet, telephony, SMS texting and ISDN network for ocean-going vessels using portable domed terminal antennas. These terminal antennas range in size from 291 × 275 mm (The FB150) to the largest 605mm x 630mm (FB500) system, which is capable of 432 kbit/s speeds. These antennas, and corresponding indoor controllers, are used to connect phones and laptop computers from sailing vessels, on any ocean, with the rest of the world. All FleetBroadband antennas require line-of-sight to one of three geosynchronous orbit satellites, so the terminal can be used anywhere, even on land.
The FleetBroadband network was developed by Inmarsat and is composed of three geosynchronous orbiting satellites called I-4 that allow contiguous global coverage, except for the poles. FleetBroadband systems installed on vessels may travel from ocean to ocean without human interaction. If there is line-of sight to one of the three I-4 satellites, then connectivity can be achieved, even in rough rolling seas. Since the FleetBroadband network uses the L band, rain fade is much less of an issue than the larger VSAT Ku band or C Band systems.
The FleetBroadband service was modeled after terrestrial Internet services where IP-based traffic Internet Protocol dominated over ISDN and other earlier communication protocols. Many corporations and IT departments are standardizing around IP traffic for data, and voice and text communication, so it is assumed Inmarsat is filling that long-term communications requirement.
There are three terminal antenna types available. The small FB150 antenna (291 × 275 mm) capable of 150 kbit/s, to the mid-sized FB250 antenna (329 × 276 mm) capable of 284 kbit/s, to the largest and fastest FB500 antenna (605 × 630 mm) capable of up to 432 kbit/s. Current manufactures of FleetBroadband systems includes Thrane & Thrane (Sailor Systems), Wideye (Skipper), KVH, and JRC.
FleetBroadband service is available globally except for the poles.[1] A coverage map is provided on an external link below.
