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Guest Chris Juricich

WAAS up? Some questions...

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Guest Chris Juricich

Can anyone demystify this concept for me? I understand it, generally, but here are some specifics.

 

?If using a Garmin device, I understand that on the West Coast (where I am), the satellite that carries WAAS corrections/updates is #47. Is this true, or is it any number above that? My understanding is that this 'bird' is located low on the horizon and is somewhere out over the Pacific (hence it's nomenclature POR -Pacific Ocean Region-).

 

?Can I select to use WAAS on a WAAS-enabled device or does it automatically choose this option?

 

?How might a non-WAAS signal give better reception than a WAAS signal? Somebody mentioned this but I don't get it.

 

?Being on the West Coast near loads of Coast Guard facilities, etc., do I have a better chance of getting 'good' WAAS reception?

 

That's it for now-- any help appreciated!

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Guest Chris Juricich

OK, not being a complete dork, and having done a bit of web research, I think I've got it.

 

All thanks to this page:

 

http://celia.mehaffey.com/dale/dgps.htm

 

Very helpful-- and as it describes the two satellites which do WAAS on the west coast and where they're located (both at zero latitude-the equator in the Pacific and the Atlantic), the higher your latitude the lower in the southern sky these little folks are. Purportedly, those on the West Coast mightaccess Satellite #35 in the Atlantic as well as Satellite #47 in the Pacific.

 

WAAS is something you enable on your device, and needn't be used constantly. One must first download from the Sats an 'almanac' or packet of info which it would use in the future. This takes about five minutes of delivery time so choose your spot carefully to pick up this signal.

 

Got more to read, but it's a very helpful page!

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Guest Kerry

quote:
Originally posted by Chris Juricich:

 

?If using a Garmin device, I understand that on the West Coast (where I am), the satellite that carries WAAS corrections/updates is #47. Is this true, or is it any number above that? My understanding is that this 'bird' is located low on the horizon and is somewhere out over the Pacific (hence it's nomenclature POR -Pacific Ocean Region-).


 

Those are Garmin #'s for these satellites which are geo-stationary Inmarsat vehicles. In WAAS terms POR is known as PRN134 and AOR-W (Atlantic West) is PRN 122. POR is located here http://www.lyngsat.com/tracker/inmar3f3.shtml

 

quote:

?Can I select to use WAAS on a WAAS-enabled device or does it automatically choose this option?


 

Selectable as other differential systems are also still supported.

 

quote:

?How might a non-WAAS signal give better reception than a WAAS signal? Somebody mentioned this but I don't get it.


 

The WAAS signal is not optimized for ground based differential at all so obstructions/interference of the signal can affect reception.

 

quote:

?Being on the West Coast near loads of Coast Guard facilities, etc., do I have a better chance of getting 'good' WAAS reception?


 

No, has nothing to do with location of those types of facilities at all. It basically has to do with being in a location which has a clear view of the WAAS satellite(s) without interference or obstructions.

 

It's a system optimized for aircraft and not ground based activities.

 

Cheers, Kerry.

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Guest Iron Chef

face="Verdana, Arial">quote:


Originally posted by Chris Juricich:

?How might a non-WAAS signal give better reception than a WAAS signal? Somebody mentioned this but I don't get it.


 

If your view of the 47 or 35 birds is obstructed then having WAAS on is useless. And since they sit so low on the horizon the problem is only increased. So... sometimes it is just worth it to track all 12 regular birds than 10 and the 2 WAAS birdies that you can't see. This can help with the accuracy and dependability of the regular signal. At least this has been my experience. Also you save battery life because WAAS sucks up batteries like there is no tomorrow. With my Etrex Venture I save about 3-4 hours worth of battery time if I leave WAAS off (which is normally the case because of mountains and such). I hope this helps a bit.

 

------------------

-Iron Chef

_ _ _ _ _ _ _ _ _ _ _ _ _

agefive.com/geocache/ ~ Fe-26

Lets Drive Fast and Eat Cheese!

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