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Distance and diversity

时间:2013-03-05 21:38来源:中国集群通信网 作者:admin 点击:
Also present at the show was the TETRA infrastructure manufacturer 3T Communications, once a part of Frequentis but now owned by Sepura.

DSC02190.jpgAlso present at the show was the TETRA infrastructure manufacturer 3T Communications, once a part of Frequentis but now owned by Sepura. 

“We do networks starting from single site up to multi-site with hundreds of base stations”, said Erich Pfaffelmayer, of 3T. “We are strong in the commercial market, especially, for example, in power utilities. We have a lot of offshore projects; we do local government, including public transport, and a lot in industries like oil and gas, with intrinsically-safe radios.”

A speciality of the company is exploiting some of the lesser-known features of TETRA. For example, it offers long-distance TETRA, for uses such as air-to-ground communication with rescue helicopters. “This means that we can communicate further than about 50–60 km, which is normally the limit due to the TETRA coded signals”, Mr Pfaffelmayer said. “We did, for example, tests in Iceland with a distance of about 115 km – provided there is line of sight, of course! It’s reducing the header to allow longer distances.”

Another special feature he highlighted is the digital equalizer built into 3T’s TETRA base stations, which enables them to deliver good reception even amid problems with signal reflections. “Normally if there are reflections, the signal is phase-shifted – and if you add two signals which are phase-shifted, you lose quality. But with an equalizer you can arrange that the shifted signals are synchronized, and then you gain a better output. I think our base station is the one and only in the market using an equalizer on top of diversity.”




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