Waas - Accuracy, Battery Life And Aquisition Speed

[+DaveA]

I have noticed while reading these forums that there is a discrepancy in GPS user's perception of WAAS. I am trying to get a handle on what accounts for the difference in how folks perceive WAAS.

 

Please list your general location, the GPS unit you use, whether you feel WAAS eats your batteries faster than if not using it, whether you consider your accuracy improved with it and roughly how long it takes for you to get a good WAAS lock with clear skies.

 

For me:

 

Location: Wisconsin

Unit: Magellan Color

Eats batteries: No

Accuracy improved: Yes

Time to lock: About the same as getting the first 4 sats locked.

[+woggie]

I just enabled WAAS on my GPSr last week, I have been driving around town and have yet to see it actually enabled:

 

Location: DFW

Unit: Garmin Quest

Eats batteries: Not Sure

Accuracy improved: Not Sure

Time to lock: Unable to acquire best I can tell

 

The documentation for the Quest is not very detailed but from what I can tell it will show "2D Differential or 3D Differential" on the GPS info screen if it is running in WAAS mode. I never get this on my GPS.

[+JohnnyVegas]

Location: Ca.

Unit: Magellan Meridian Gold, Sport Trac, Sport track color

Eats Batteries: As there are several typs of Batteries made by several manufactures, this would be a very hard question for anyone to answere.

Acuracy improved: Again, this is a hard question to answere, if you are looking for a cache, you have no way of knowing how accurate the coordinates for the cache you are looking for.

Time to look: this depends on how long a GPS has been turned off. WAAS will not slow down the time it takes a GPS to get a lock, but for WAAS to work the GPS has to build up an almanac of WAAS corrections, this can take some time.

WAAS is a sytem that is intended for use in Norht America, the European system is called EGNOS. WAAS and EGNOS will work in any GPS that has WAAS built into it.

 

 

From Garmins site:

WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.

 

There was a link posted in another thread not long ago the was to a very detailed explanation of WAAS, If I can find it I will add it.

[+JohnnyVegas]

Here is the link regarding WAAS

 

WAAS

[+DaveA]

Acuracy improved: Again, this is a hard question to answere, if you are looking for a cache, you have no way of knowing how accurate the coordinates for the cache you are looking for.

 

Trying to determine accuracy by how close one gets to a cache is pointless, but it is easy to test one's unit by setting it in a known sport for a few minutes and saving the waypoint. Turn off unit and put it back in place for a few minutes with the waypoint active. Look at how far the unit says it is from the waypoint. This is an easy accuracy test.

 

Time to look: this depends on how long a GPS has been turned off. WAAS will not slow down the time it takes a GPS to get a lock, but for WAAS to work the GPS has to build up an almanac of WAAS corrections, this can take some time.

 

I am only interested in how long it takes from a warm boot. Cold boots have variables. If your unit has been on within the last few weeks and it is within 500 miles of when it was last on, how long, roughly, does it take before WAAS tracking, if possible, begins?

 

There was a link posted in another thread not long ago the was to a very detailed explanation of WAAS, If I can find it I will add it.

 

Please don't, at least not in this thread. I would like to just see the raw data people submit, I don't need a WAAS primer, I want to see real life experiences.

[+Poindexter]

Location: Maryland

 

Unit: Garmin GPSMap76S

 

Eats batteries:No (I have bench tested the current draw with and without WAAS and there is no discernable difference observed with this unit)

 

Accuracy improved: According to the EPE, yes. Not tested against a better standard

 

Time to lock: About the same as getting the first 4 sat's locked

[+StarBrand]

Location: Western Nebraska

Unit(s): Garmin Legend, Garmin Rino 120, Garmin 60C

Eats Batteries: maybe 10% - 15% less battery life then when it is off

Aqusition time: 3 - 4 minutes but keep in mind that it takes about 10 minutes or so to download all of the corrections

Accuracy: Hard to measure but EPE reports better and it at least "seems" better for lack of a highly accurate test

 

I use it when I can especially for hides.

[+Jeep_Dog]

Location: Central Texas

Unit: Garmin Etrex Venture

Eats batteries: Alkaline: No discernable difference. NiCad rechargeable: Perhaps a 10% or so degredation in battery life.

Accuracy improved: Yes 90% of the time

Time to lock: 4-10 minutes.

 

Accuracy expounded: on three occasions I noticed my GPSr acting erratically (pointer jumping all over the place even 150-200 feet from cache location). Shutting off WAAS got the GPSr to give better results and "behave" in all three cases. 90% of the time WAAS will improve accuracy from 15-23 feet to 6-10 feet, and helpful with really pesky micros out in big, wide-open areas (otherwise, with standard ammo can, not really needed).

[+woggie]

I sat out in my parking lot for about (20) minutes and was able to "see" that id did register the WAAS signals and I would show 3D Differential and I would have the "D" on the signal strength bars. However, it appears it does not stay "attached" for an extended period of time. When I drove off it would come and go as well. The one thing I did find out, whether it is 100% true, is the WAAS system in this metro area is not officially "online" as of yet. I have a friend that is a pilot and he has been keeping an eye on WAAS in our area and the FAA has not reported that is is active. The few times I was able to maintain a signal it appeared to show better accuracy but have not been able to validate this.

 

Thanks,

jaw

[+StarBrand]

I sat out in my parking lot for about (20) minutes and was able to "see" that id did register the WAAS signals and I would show 3D Differential and I would have the "D" on the signal strength bars. However, it appears it does not stay "attached" for an extended period of time. When I drove off it would come and go as well. The one thing I did find out, whether it is 100% true, is the WAAS system in this metro area is not officially "online" as of yet. I have a friend that is a pilot and he has been keeping an eye on WAAS in our area and the FAA has not reported that is is active. The few times I was able to maintain a signal it appeared to show better accuracy but have not been able to validate this.

 

Thanks,

jaw

Since WAAS is run via a satellite, it should be up and working so long as you are in North America. A complimentery system for Airports called LAAS might not be running yet at your local airport. LAAS=local Area Augmentation Sysytem

[dsandbro]

Since the WAAS satellites are over the equator they are low over the southern horizon from most of North America. If there are tall obstacles to your south (like a mountain or buildings) you may not get a clean signal.

 

Distance from one of the ground reference stations will vary the accuracy. The WAAS signal corrects for distortion at the reference sites. If you are more than 200 miles from any stations the corrections decline in accuracy for you.

[+RJFerret]

Topical as I JUST bought a 60CS to replace my Yellow for predominantly this reason. (Found myself 60' in the wrong direction at 2:00 am yesterday while my Gecko friend went right to it!)

 

I just returned from comparing my old Yellow against the 60CS at a GPS-verified benchmark down by the beach (read, great reception along LI sound).

 

Location: Connecticut

Unit: Garmin 60CS

Eats batteries: No (although the manual says it uses more, not as much as compass though!)

Accuracy improved: Yes (zero'd on benchmark with WAAS, 4' without)

Time to lock: couple minutes until full "D"s & WAAS sat locked solid

 

(Although the little D's show up on individual bars while it's working on locking the WAAS sat--but I wasn't timing that.)

 

Just for reference, my eTrex didn't get closer than 20' to the benchmark...

 

Enjoy,

 

Randy

[+IVxIV]

Location: Ontario Canada

 

Unit: Lowrance iFinder Pro

 

Eats Batteries: Well, perhaps yes & no. With the iFinder if you switch off WAAS you reduce the sampling rate at the same time. So, as as default the battery life does improve with Waas off. "How much" the Wass-off contributes to battery savings may be a mystery

 

Improves accuracy: Dunno that one with any certainty either. The jury seems out whether or not Wass even works in Canada.. although I do see the Waas strength meter shows signs of life when I'm using it.

 

Time to lock: Seems about the same, well give or take a few seconds