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Changes to WAAS constellation

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I received the following email last week regarding changes to the WAAS constellation. I suspect the change will impact those who will be post-processing their data but it seems like it will impact others as well. Does anyone know if Garmin has or will be updating their firmware to reflect these changes?




On July 31, 2007, the FAA will decommission WAAS satellites 122 and 134, leaving satellites 135 and 138 for WAAS differential corrections in North America.


In order to continue receiving WAAS differential corrections after the July 31, 2007 cutoff date, receivers must have updated WAAS firmware loaded onto their systems or have satellites 135 and 138 manually selected through a terminal communication program.


Customers should check with their GPS manufacturer to see if firmware updates are required for their particular GPS receiver brand and model.


Currently there are three WAAS satellites broadcasting correction signals for North America (PRNs 122, 134, and 135). An additional WAAS satellite (PRN-138) is available for non-aviation use. PRN-138 has not been fully commissioned and is still undergoing testing. Its planned release date is in July 2007. Also in July 2007, PRN- 122 and PRN-134 will be decommissioned. This means that PRN-135 and PRN-138 will be the only active WAAS signal satellites for North America. Receivers that are not in a scan mode or are locked on to PRN-122 or PRN-134 will need to be adjusted or programmed to receive either PRN-135 or PRN-138. This dual redundancy coverage means there would have to be an outage of both correction satellites for service to be lost.


PRN 122 and 134 will be decommissioned on Tuesday, July 31, 2007. PRN 138 will be placed into service (commissioned) on Wednesday,July 11, 2007.

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This was posted here several days ago. Yes, 35 and 47 are decomissioned, and 48 and 51 are operational for WAAS. Your recievers should already be picking these up, and should have for some time. Just one is needed to provide corrections for the other GPS sats. Both cover all the US and most of Canada. When you are recieving corrections you should see little D's on the sat bars for Garmin and I think W's for Magellans.


All is well.

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