High speed broadband via geostationary satellite

Rudolph Muller

Rudolph Muller is the editor at MyBroadband and covers telecoms and broadband news. Rudolph comes from an academic background, but left the University of...

Full Profile

E-mail

But there is now light on the horizon, or should I rather say “broadband” on the horizon!

In February this year Ses Astra launched its ASTRA2Connect internet services in central and west Africa, providing broadband as well as VoIP services to large under-serviced areas. The service will soon be expanded to the rest of Africa, including South Africa.

In October 2008 Ses Astra ordered a new satellite from one of the world’s largest designers and manufacturers of satellites. The satellite is destined to be placed on a 5º orbit later this year. Designated ASTA 4B, the satellite will have 24 direct-to-home transponders for both broadcast and broadband connectivity.

The Astra2Connect service is a bi-directional satellite broadband that enables always-on high speed internet access regardless of its user’s geographical location.

Speaking at SATCOM Africa 2010 Norbert Willems, MD ASTRA Broadband Services said that ASTRA2Connect uses a satellite link to carry internet protocol data in both directions between the central hub and remote terminals. “At the hub, routers connect to the internet backbone and internet protocol (IP) data is embedded in a DVB-S2 format carrier to be uplinked to the satellite from SES ASTRA’s teleport. From there it is down-linked to the remote terminal where the signal is received with a domestic-type dish for the satellite internet modem, which extracts the IP data for the end user’s PC.

“The return path is handled in a similar fashion, but with a low power 500 mW transmitter on the terminal dish providing the uplink to the satellite, with multiple-frequency time division multiple access techniques employed to handle many remote terminals simultaneously. With the satellite in a 5º East orbit only a 100 cm dish will be required.”

Once in orbit ASTRA 4B will provide speeds of up to 4096 kbps downlink and 256 kbps uplink. Signals are fully encrypted on both the forward and return path. Other techniques such as selective content compression and pre-fetching will provide for faster page loading. The technology offers triple play providing internet, VoIP telephony and TV and radio from the satellite and the same home dish.

Various internet service providers have shown interest in offering the new service while some regulatory issues are being addressed ahead of the service being available to South Africans. Will it be expensive? According to Willems, “affordable”.

The idea of using that position in space to provide communication over a very large area is by no means new. It was first mooted in 1928 by Herman Poto?nik, a Slovenian rocket engineer and pioneer of cosmonautics. However Arthur C Clarke gave real meaning to the idea in his article “Extra-terrestrial relays – can rocket stations give worldwide radio coverage?” published in Wireless World in 1945. Here Clarke was the first to describe it as a useful orbit for communications satellites for broadcast and relay purposes.

In some quarters a geostationary orbit is referred to as the Clarke Orbit. Similarly, the Clarke Belt is the part of space approximately 36 000 km above sea level, in the plane of the equator. Placing Astra 4B at 5º East means that its antenna beams give good coverage over Africa and most of Europe.

Add “geostationary orbit” to your favourite search engine to read some interesting articles about space communication.

Broadband via satellite << online discussion

EngineerIT