To WAAS or not to WAAS...That is the question(for V owners, anyway)

[Alphawolf]

O.K. I can see the need (desire) for WAAS when you are geocaching or something like that, off road. But can someone explain why I would want to slow down my machine, by enabling WAAS when I am street driving? As we all know, it puts your re-calculation times in the dirt when WAAS in enabled. I can't see where WAAS would give you one bit of an edge when street driving. But it sure does make things slow down! Comments??

 

"Never take a sunset for granted. Stop what you are doing and enjoy it. You never know when it may be your last"

[umc]

I cannot comment on the question since I only had my V for V days now. But somewhere in this thread could someone explain WAAS a little bit because I don't fully understand what it is or does. As far as I know they are a set of satellites that are used for averaging. I haven't had the time as of late to do the research on a lot of things. Maybe I should spend less time on here and find my own answers What an idea.

 

Seriously WHAAAAATS WAAS?

 

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Confused New Owner Of a Garmin GPS V Received on 10-03-02

[umc]

I cannot comment on the question since I only had my V for V days now. But somewhere in this thread could someone explain WAAS a little bit because I don't fully understand what it is or does. As far as I know they are a set of satellites that are used for averaging. I haven't had the time as of late to do the research on a lot of things. Maybe I should spend less time on here and find my own answers What an idea.

 

Seriously WHAAAAATS WAAS?

 

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Confused New Owner Of a Garmin GPS V Received on 10-03-02

[+Centaur]

Sometimes im just to lazy to turn WAAS off.

But yea, if I am doing alot of route recalcs I will shut it off. If im doing a long drive Ill be using the roof top antenna anyway, and that locks up nearly every bird in the sky, so ill see 20 foot EPE without WAAS anywho.

-Centaur

[+Centaur]

Sometimes im just to lazy to turn WAAS off.

But yea, if I am doing alot of route recalcs I will shut it off. If im doing a long drive Ill be using the roof top antenna anyway, and that locks up nearly every bird in the sky, so ill see 20 foot EPE without WAAS anywho.

-Centaur

[SergZak]

Although I am able to pick up the WAAS birds here in the suburbs of Los Angeles, I prefer to simply leave it disabled because as you said, it slows processing time down and in my case, doesn't increase accuracy a bit. If it did improve my accuracy, a few feet of increased accuracy wouldn't make any difference while driving anyways.

[+Crusso]

Had it turned on when I first got the V. Said "Wow, increased accuracy! Now have it turned off since the result is negligable & my V slowed to a crawl. AS it is the dadgum thing tells me to make U-turns on the highway & takes 45 minutes to an hr to load 19 meg worth of maps that are loaded with every Tom, Dick & Harry's gas station, deli & barber shop!

 

Wherever you go, there you are!

[+Crusso]

Had it turned on when I first got the V. Said "Wow, increased accuracy! Now have it turned off since the result is negligable & my V slowed to a crawl. AS it is the dadgum thing tells me to make U-turns on the highway & takes 45 minutes to an hr to load 19 meg worth of maps that are loaded with every Tom, Dick & Harry's gas station, deli & barber shop!

 

Wherever you go, there you are!

[+Criminal]

Sadly, they didn't launch the WAAS sats for "recreational" GPS users. It was meant for airplanes who's antennas are positioned a wee bit higher than most.

 

But it's still cool to see single digit EPEs every now and then.

 

If your house catches afire, and there aint no water around,

If your house catches afire, and there aint no water around,

Throw your jelly out the window; let the dog-gone shack burn down.

**Huddie Ledbetter**

[+embra]

umc--you can find out more about WAAS here.

 

max

Just visiting this planet

[+bigeddy]

quote:

---

Originally posted by umc:

Seriously WHAAAAATS WAAS?

---

WAAS = Wide Area Augmentation System

 

Depending on your ability to digest acronyms, you can learn about WAAS by reading the FAA explanation or the Garmin explanation.

 

It was developed by the Federal Aviation Administration as a basic aircraft navigation aid in the U.S. For ground users like us it provides 1-2 m horizontal accuracy and 2-3 m vertical accuracy in relatively open terrain. It doesn't help much, if at all, where terrain, trees or buildings block the special satellites over the equator.

[umc]

Got it thanks all. Now the next question would be and I will RTFM at some point but I think my V shows the WAAS sats with little 'D's on them. Is that true?

 

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Confused New Owner Of a Garmin GPS V Received on 10-03-02

[+EraSeek]

It slows your unit down? ReallY? I've used it while driving and have never noticed this. Of coarse I'm just using the base map, so maybe if you have a map program loaded in this makes a difference. As for me, I've never seen any slowing in my map76. As for why use it... sometimes I like to watch it and go wow! and often I use it when I am placing a cache to get a more accurate coordinate. Other than that I leave it off to save on batteries.

 

 

Think about it though...this was created for aviation. Surely if it slowed down when providing a position for an airplane, it would defeat the purpose of WAAS. SOooo... this problem must come in play with handhelds loaded up with big mapping programs, don't you think?

[+apersson850]

WAAS satellites have PRN number from 33 and up. Satellites that show a 'D' in the signal strength bar aren't necessarily WAAS satellites, but they are corrected using WAAS data.

 

The WAAS calculations are obviously complicated. That's why the GPS seems to run slower when WAAS is on, since there is yet another thread running in the software, consuming available CPU cycles while getting the correction data correct (!).

Even in non-autorouting units, like the Vista, you can notice the slower speed. Try driving somewhere, with the MetroGuide map displayed with track up. Make a turn, and pay attention to how long time it takes for the map to be turned to show your new heading.

 

In an aircraft, they can have a lot more capable processors in their equipment, since they don't have to worry about running it from some small AA cells.

 

Anders

[Timothius]

I have not seen a significant gain in accuracy by using WAAS. In fact sometimes instead of being within 10 meters or so the accuracy goes out to 30 meters or so using WAAS. Thats with 4 or 5 satelites pegged with d's.

 

At this point I don't see the benefit of WAAS Perhaps after they launch a few more birds it will get better.

 

Timothius

 

An Irish Toast:

"May you be in heaven a half hour before

the Devil knows you're dead"

[+apersson850]

As far as I've understood, they can fill the sky with WAAS satellites, but that will not improve the accuracy at all. It will in that case only improve the ability to get WAAS information (which isn't unessential, of course).

 

The WAAS information is differential, i.e. it's derived from ground stations, which measure their position according to GPS, and compare with their known position. From that, a necessary correction to compensate for errors introduced by electrical charges in the ionosphere, for example, can be computed. These corrections are then broadcasted by the WAAS birds. From this principle, it seems evident to me that the WAAS birds themselves doesn't add much in accuracy. It's the information they transmit, and that is derived from the ground stations.

 

Besides, a complete WAAS information transmission cycle is ten minutes long. Chances are large that it's interrupted occasionally (which is something that improves with more WAAS satellites). So it may last several data cycles before your receiver is completely updated, and can make full benefit from the WAAS signals.

 

This is all compiled from hearsay, since there is no space-based augmentation system in full operation where I live, so I don't have any hands-on experience.

 

Anders

[+ZachNLiam]

When I had my V I never turned WAAS on. Now, with my SPIII it doesn't even have WAAS capability, so Garmin obviously thinks it's not important for street use.

 

The MAP76 does not seem to be affected at ALL with its map redraws with WAAS on or off, so I always leave it on.

 

With road lock and maps having a potential error of 20 feet or more, I'm sure it would make no difference on the road.

[+GOT GPS?]

WAAS is great for boating, and flying your small airplane, but not when you have obstructed view of the sky.

 

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