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The new Ka band that ISRO is heralding in the country on its latest satellite GSat-4 will improve the bandwidth for the Net user and also drive down the price noticeably.
But not immediately. The customer has to wait for three more years to feel the effect of its real operation, according to Mr K.R. Sridhara Murthi, Managing Director of ISRO's commercial arm, Antrix Corporation. GSat-4 is an experimental satellite with a multi-beam Ka-band transponder.
The Ku band has got crowded and it is believed that Ka, which can support higher data transmission by at least two or three fold, will be preferred for non-broadcasting applications.
The biggest advantages of Ka band are the higher bandwidth it offers, a 20-30-cm antenna that is almost half the diameter of the present Ku band dishes; and transmission over small areas at higher power. The C-band antenna was 2 metres wide.
On the flip side, Ka transmission is vulnerable to outages during rain. “One big issue with the Ka band for our country is attentuation or rain-fade, which is worse than with Ku band. Communication can be impaired during rain,” Mr Murthi told Business Line. He was speaking ahead of the launch of the advanced communications satellite slated for Thursday evening from Sriharikota.
With Ka, the entire country can be covered much more efficiently in 20-50 spot beams instead of using one big beam. The same frequency can be re-used for different users without interference. “You can use this more amenably for Internet broadband services. It may not be preferred for DTH or broadcasting which needs very big beams,” Mr Murthi said. The multiple beams have been tried out with another experimental service, the Edusat.
Potential users are VSAT operators, rural Internet connectivity where cables will not go; for video conferencing and certain user groups.
Ka services may cost more in the beginning because of new equipment that the service provider has to install. But as with Ku band equipment, over time and number of sales, it can get cheaper than Ku. The price of terminals is ruling at $200-$300, which should not be a big constraint for operators, Mr Murthi said.
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By 2013, ISRO plans to have a fully operational Ka-band satellite, the GSat-14. “I'm sure Ka will click technologically. It is very much part of future technology. While you may enjoy new recipes, you also cherish the older ones. Ka, when it gets operational, will complement C and Ku bands that we have used so far.”
Reports say the world is certainly moving towards Ka, and for new and lucrative applications. Of the 75-plus communications satellites going into service between now and 2014, some 30-35 will have Ka band transponders.
ISRO is building Hylas-1 with Ka transponders for UK operator Avanti. The other large Ka projects include Hylas-2, DirecTV, EutelSat Ka-Sat, Yahsat 1A and 1B; and ABS-2.
Meanwhile, Mr Murthi said, “We have to measure the extent of fading. With C and Ku bands, the quality of service was 99.9 per cent. We don't know yet how good this would be for DTH operations.” In the West, impaired communication has been managed with some technical solutions, he said.
The Space Applications Centre, Ahmedabad, which developed the payload, is also understood to be working on solutions for the industry on how to beat the rain fade problem.