International Dredging Review

International Dredging Review

OmniSTAR Inc. is in the final testing stages of a new wide area differential GPS service that has been achieving consistent six-inch horizontal accuracy in its test receivers. Named OmniSTAR HP (high performance) the system will be available to users by subscription. The HP GPS correction signals will be broadcast by several geostationary satellites to users throughout the world.

“This level of wide-area real-time accuracy is a goal toward which the industry has been striving for quite some time.” said John Pointon director of sales and marketing for OmniSTAR.

When selective availability was turned off on May 1 2000 the accuracy of uncorrected positions from GPS which had been +/- 100 meters for the civilian user improved to +/- 5 – 8 meters. Because this accuracy was still not good enough for many dredging surveying and construction applications governments and private companies continued to require methods of correcting for systematic and atmospheric effects in the signal. However the best horizontal accuracy currently achievable by L1 Differential GPS systems such as ‘standard’ OmniSTAR is sub-meter at best.

The Federal Aviation Administration’s (FAA’s) wide area augmentation system (WAAS) cost taxpayers more than a billion dollars and achieves an accuracy of 1 – 3 meters. EGNOS (the European geostationary navigation overlay system) augments the performance of GPS and the Russian Glonass constellations. MSAS (MTSAT satellite based augmentation system) was developed by the Japanese for the same purpose.

Real Time Kinematic (RTK) can achieve centimeter accuracy using two dual frequency receivers as mobile station and base station but range from the base station is limited system operation is sensitive and this technique can require $50000 worth of equipment.

This year OmniSTAR is finalizing its development of an enhanced system to provide very high accuracy broadcast correction signals over a wide area. The service will cover entire continents and only requires an OmniSTAR HP-capable receiver costing approximately $10000 to $15000 and an annual subscription which will probably be $2500 in North America.

The initial results from the beta test installations are encouraging said Pointon. Routinely OmniSTAR has up to 35 Differential GPS systems on test every day 24 hours a day using more than 30 combinations of GPS receiver and correction signal. The HP receivers are showing steady six-inch accuracy he said.

“OmniSTAR HP is going to do this” he said. “It appears to be possible.”

Though the company produced receivers for the tests they do not plan to manufacture hardware said Pointon. Rather existing GPS hardware manufacturers will add OmniSTAR HP capability where needed.

OmniSTAR Inc. is a Fugro company with headquarters in Houston. Sister company Fugro-Chance headquartered in Lafayette Louisiana was a partner in developing the HP system. Fugro-Chance was formerly John E. Chance and Associates.

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