Late last week I received word from Jay Riester at Seiler Instrument that due to changes in the Wide Area Augmentation System (WAAS), users of certain Trimble GPS receivers should check their firmware and upgrade if they want to avoid problems receiving WAAS corrections. According to information from Trimble, this is a result of two WAAS satellites going out of service on July 16th, 2007.
WAAS is a free differential GPS correction signal maintained by the Federal Aviation Administration (FAA) to support civil aviation. Because WAAS improves the positional accuracy of non-corrected GPS signals to less than three meters (or better) under the right conditions, many GPS receivers support WAAS.
Unfortunately, in digging for sources other than Trimble, I could locate very little information on any broader implications for non-Trimble users, especially consumer-grade receivers The usual Google searches turned up almost nothing of interest, nor did visits to the Garmin and Magellan Web sites. This leads me to wonder how widespread the problem might be beyond Trimble.
Do you know anything about the WAAS satellite changeover, or have information from a source other than Trimble? Mail me with the details.