Waas

[+BigFurryMonster]

On my Garmin GPSMap60CS, I have the option of turning WAAS on or off. I've done some searching on the benefits of this feature, but it is quite unclear to me whether I should use it or not.

 

pros:

• It is said to improve the signal fix. Garmin claims to an accuracy of 3m and better, but I rarely even get an EPE of 4m with WAAS.
  

cons:

• I'm not even sure WAAS will work. Garmin says ( http://www.garmin.com/aboutGPS/waas.html ) that it's US only, and I'm in Europe. Maybe I should be using the other system "EGNOS" instead, but I don't know how. Does it work similar to WAAS?
  
• I seem to receive satellites with ID higher than 32 now and then, but no 'D' shows up as explained in this thread: http://forums.Groundspeak.com/GC/index.php...=0entry937392
  
• WAAS may drain my batteries faster.
  

Any comments? Additions to this list?

 

Any URL pointing to the current state of WAAS?

 

Should I upload an 'almanac' to my GPS-r, as explained here?

http://www.gpsinformation.org/dale/dgps.htm#waas

Edited April 6, 2005 by BigFurryMonster

[+tirediron]

My personal recommendation is to turn WAAS off, even when you're in an area with WAAS coverage. On the few occasions where I have been in position to try it, the only noticeable affect has been to slow things down considerably - it does increase your accuracy if you can get a good lock on WAAS satellites, but did the hider use WAAS?

 

You don't want it on regardless, as you are welllll outside the coverage area. Here are a couple of links with info:

 

WAAS

 

More WAAS

[+JohnnyVegas]

In Europe WAAS coverage is provided by the European countries under another name, I think it is called EGNOS. For WASS to work you must let your GPS run for about 15 minutes so that the GPS can build an almanac af data. As far as WASS slowing things down, I doubt this is even noticable, load a very large map into a GPS can slow down how has your screen updates.

 

Weather or not someone who had hid a cache used WAAS is a very poor reason to turn WAAS off.

 

1st. - There are other things that will effect GPS accuracy when hidding a cache that you have no control over like trees and large buildings or being next to a large cliff or the side of a canyon can be a real problem.

 

2nd. - if the person who hid the cache was using WAAS, wouldn't you want to have it on. If the person who hid the cache uses a Magellan GPS they will have had WASS turned on unless they know how to turn off the WASS feature which is not really covered in Magellans instructions.

Unless someone mentions in the cache page that they used WAAS you have know way of knowing if they had WAAS turned on.

 

Edit to add WAAS link

 

WAAS

Edited April 6, 2005 by JohnnyVegas

[reidster]

I always leave WAAS on and I pretty much agree with everything that JV has mentioned.

 

Its effect on battery drain is always being disputed, but for me it's a non-issue.

I'd worry more about a battery's charge and capacity first.

Besides, I always carry spares, lots of them.

Also like JV said, it seems maps have a far greater impact on speed than WAAS/EGNOS calculations.

 

I think the Dale DePriest WAAS page that is listed is very good, accurate, and informative.

Beware! There are many other similar pages posted by well-respected individuals that are out-of-date and contain errors!

 

WAAS has been certified in the US for navigation by commercial aviation, July 2003.

The "WAAS" system is only usable in the US. EGNOS is the European equivalent.

The generic term for both is SBAS (Space Based Augmentation System).

Fortunately the data structures are identical and a GPSr should work in both places.

Therefore I think using one or the other should be transparent. (Anyone know for sure?)

 

SBAS, it's a Grid thing… (please reference Dale's WAAS page)

The main difference is where each system has their respective ground reference stations.

The biggest error these systems correct is the ionosphere related signal delay.

Although the Iono-correction grid covers most of the Earth, only points covered and calculated by the ground-based systems are up-linked.

It is these grid point corrections your GPSr needs for the most benefit.

 

I hope this was helpful, reid.

[GeoBobC]

If you have a Garmin 60c/60cs check out this post:

 

http://forums.Groundspeak.com/GC/index.php...0entry1411520

 

Garmin made some changes in the 3.70 firmwares that are design to help with EGNOS signals, but can be at the expense of U.S. WAAS signals.

[+Marky]

For WAAS to work you must let your GPS run for about 15 minutes so that the GPS can build an almanac af data.

That is a very cool tidbit if information, especially for hiders. I've always wondered why WAAS took so long to kick in after turning on my GPS.

 

If you are hiding caches, please use WAAS, it results in much, much better averaged coords in most cases.

 

--Marky

[+The Blorenges]

WAAS and EGNOS (Europe) work the same way. Ground stations pick up the normal GPS satelite signal and retransmit it to geo-stationary satelites. The signal is accurately corrected for position by the ground station. The geo-stationary satelites then send a signal down to your GPS which will correct the normal signal from the GPS satellites improving accuracy - reckoned to be down to 3 meters. In Europe the EGNOS satellites are not operational yet. The latest news from the European space agency is EGNOS will be operational for 'non critical situations' in June 2005. But it is nearly 2 years late so we are not holding our breath! The satellites are broadcasting test signals so sometimes I can pick them up (Garmin Etrex Legend). The indication is a letter 'D' in the normal satelite bar. But its not a reliable service. Suggest you check out the forums at www.globalpositioningsystems.co.uk (UK GPS supplier). For Garmin users here are the EGNOS/WAAS satelite numbers that appear in the display:

33 EGNOS AOR-E (Inmarsat 3 F2) 30 200 Atlantic Ocean Region - East

35 WAAS AOR-W (Inmarsat 3 F4) Atlantic Ocean Region - West

37 EGNOS Artemis 27 152

39 EGNOS IOR-W (Inmarsat 3 F5) 26 147 Indian Ocean Region - West

42 MSAS (Japan)

44 ESTB IOR (Inmarsat 3 F1) 6 110 Indian Ocean Region - East

47 WAAS POR (Inmarsat 3 F3) Pacific Ocean Region

50 MSAS (Japan)

 

AOR = Atlantic Ocean Region, IOR = Indian, POR = Pacific

In the UK (South Wales) I can pick up 33, 39 (low) and 37.

Hope this helps

Chris

[Little-Acorn]

My older Garmin Emap (not WAAS-enabled) has led me to within a foot of the location of the first two caches I tried to find. Was I just lucky?

 

Who needs WAAS?

[+Vistalia]

Do you guys have any news and information about the JAPAN MSAS or other proposed correction system in other countries?

[+ritzvin]

I tried it out when geocaching with my Legend once. It caused my locaton to jump around a lot, which was incredibly annoying - I turned it off about 1 minute later and never turned it on again. The gps with WAAS disabled was more than accurate enough, so I didn't really see a reason for using it.

Edited April 8, 2005 by ritzvin

[+ritzvin]

For WASS to work you must let your GPS run for about 15 minutes so that the GPS can build an almanac af data.

perhaps that was the problem then.

[+DBleess]

For Garmin users here are the EGNOS/WAAS satelite numbers that appear in the display:

33 EGNOS AOR-E (Inmarsat 3 F2) 30 200 Atlantic Ocean Region - East

35 WAAS AOR-W (Inmarsat 3 F4) Atlantic Ocean Region - West

37 EGNOS Artemis 27 152

39 EGNOS IOR-W (Inmarsat 3 F5) 26 147 Indian Ocean Region - West

42 MSAS (Japan)

44 ESTB IOR (Inmarsat 3 F1) 6 110 Indian Ocean Region - East

47 WAAS POR (Inmarsat 3 F3) Pacific Ocean Region

50 MSAS (Japan)

 

AOR = Atlantic Ocean Region, IOR = Indian, POR = Pacific

In the UK (South Wales) I can pick up 33, 39 (low) and 37.

Here's an old map of the coverage footprints:

 

http://www.gpsinformation.org/dale/dgps.htm#waasalmanac

 

If someone has an update with the new birds, please post it.

 

It bears repeating that the EGNOS system is still only just coming online, is still in testing and may not be reliable for a while yet. BUT when it does come online, you can expect precision to get into the 2-3 meter (6-9 foot) range as long as you have a clear view of the sky where the augmentation satellite is.

 

http://www.esa.int/esaNA/SEM8M3SMD6E_egnos_0.html

Edited April 10, 2005 by DBleess