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January 18th, 2010 admin Leave a comment Go to comments

What is WAAS and why is it important to GPS receivers?

This question came to me as I was searching for a portable navigation GPS for my car. I wondered as I researched products why some offered WAAS while others did not. So I found myself wondering what the acronym meant and how having or not having it would affect the product’s performance.

WAAS stands for Wide Area Augmentation System.

Basicaly, atmospheric conditions will reduce the accuracy of the GPS satellite signal. At any given time the best resolution from a standard GPS will be a position to within 30 ft. This is great for the average user, but a big disaster for critical users like aircraft.

Enter WAAS. To compensate for the 30ft grey area, ground stations are set up at hyper-surveyed locations. they beam their known position to different satellites, these rebroadcast the positions to WAAS enabled recievers, and the difference is mostly eliminated, producing accuracy to within 4ft.

For WAAS to work, you need to be in view of both the GPS and WAAS sattelites. There are currently only 2 WAAS satellites over the continential US, so for a car or handheld unit, WAAS accuracy is only available when you have a completely unobstucted view of the sky. This is likely to improve in the future.