23 June 2008

GPS back-up 'needs more research'

Ministers say further research is needed before a navigation system dating back to the Second World War can be used as a widespread back-up to GPS. MPs were warned this week about the vulnerability of GPS to jamming by terrorists intent on crippling vital infrastructure. They were told LORAN, a radio-based maritime navigation aid, could be used as a more robust back-up. Satellite navigation underpins much of the world's infrastructure, including financial markets, telecoms, power generation and distribution as well as transport and the emergency services. But the signal from the satellite is weak and easily jammed and is vulnerable to interference. Some experts are now pressing for LORAN to be developed as a back-up.

LORAN was originally developed during the Second World War as a maritime navigation aid and is based on the principle of the time difference between signals from a pair of radio transmitters. Its modern version, known as eLORAN, delivers higher accuracy, integrity and continuity. Its signal is much stronger than from a satellite, enabling its signal to be received indoors and even - to a limited degree - underground. It could potentially provide a more reliable positioning and timing signal and is less vulnerable to accidental interference and jamming. In one test it jammed GPS over a 50 square mile area of Cornwall over two days, warning emergency services and coastguards in advance.

More information:

http://news.bbc.co.uk/1/hi/uk_politics/7459213.stm