WAAS Managemnet

[GPS-Hermit]

I never get a straight answer when asking about WAAS.

 

If I set it on, I lose some battery power and it might be for nothing.

 

How do I tell if I would benefit from having it on. What is the D in my bars telling me.

 

Just refer me to good thread on this - if you want - kinda confused.

 

I have just purchased a Garmin GPSMAP 76CSX, want to get the best signal/battery ratio.

 

Do I set it and forget it or Observe something for my decision.

[+LR_Se7eN]

I'd like to know the answers to your Q's as well. Any takers?

[+StarBrand]

The "D" on the bars in a Garmin unit show that it is indeed receiving the correction data from a WAAS sat.

 

WAAS can significantly improve the accuracy of a unit especially in North America and particularly if you are near one of the ground based systems that help feed the correction data to the system.

 

My own tests and some websites confirm that leaving WAAS on only has a small effect on the battery life (something like 5% less or slightly more).

 

I leave it on - I use rechargables and so battery cost isn't a big issue.

 

Does it help with Geocaching?? Thats debatable, you really don't know what conditions were like at the time of the hide, no idea if WAAS was on or a WAAS sat was being recieved. So the addtional accuracy may or may not get you any closer to a cache. Just no way to know. But how can increased accuracy every be a "bad" thing?

[GPS-Hermit]

The "D" on the bars in a Garmin unit show that it is indeed receiving the correction data from a WAAS sat.

 

WAAS can significantly improve the accuracy of a unit especially in North America and particularly if you are near one of the ground based systems that help feed the correction data to the system.

 

My own tests and some websites confirm that leaving WAAS on only has a small effect on the battery life (something like 5% less or slightly more).

 

I leave it on - I use rechargables and so battery cost isn't a big issue.

 

Does it help with Geocaching?? Thats debatable, you really don't know what conditions were like at the time of the hide, no idea if WAAS was on or a WAAS sat was being recieved. So the addtional accuracy may or may not get you any closer to a cache. Just no way to know. But how can increased accuracy every be a "bad" thing?

 

Thank you - I have left it on as well.

Does the "D" still show even if you have WAAS turned off!

[+Barnie's Band of Gold]

I never get a straight answer when asking about WAAS.

 

If I set it on, I lose some battery power and it might be for nothing.

 

How do I tell if I would benefit from having it on. What is the D in my bars telling me.

 

Just refer me to good thread on this - if you want - kinda confused.

 

I have just purchased a Garmin GPSMAP 76CSX, want to get the best signal/battery ratio.

 

Do I set it and forget it or Observe something for my decision.

WAAS satellites are geo-stationary and usually very low on the horizon. To get the most effective use from them you need to have no obstructions in your "line of sight" (to the satellites). With obstructions your GPSr accuracy is highly likely to be degraded.

 

When WAAS signals are being received you will notice a "D" in the signal bars. "D" represents differential data and indicates that possible corrections are being made to your non-WAAS satellite data.

 

If you are using your unit for geocaching in the usual locations that caches are placed - WAAS represents no value (and as you note extra battery consumption).

 

Unless you are landing large airplanes in compromising conditions I would leave WAAS off.

[+twolpert]

Does the "D" still show even if you have WAAS turned off!

No. The "D" shows up only when WAAS is on, and only on those bars corresponding to satellites for which the unit is actually applying corrections. Without getting too technical, there are several different kinds of correction data available. Some of these are related to atmospheric conditions. Their applicability varies according to your location relative to the satellite in question. It is not awfully unusual to see the "D" only on some bars.

 

As far as the usefullness of WAAS to a cacher, it's like talking to lawyers. If you ask two of them, you will get three opinions. (Hope there are no lawyers in the audience -- or at least none who lack a sense of humor.)

[+StarBrand]

...WAAS satellites are geo-stationary and usually very low on the horizon. To get the most effective use from them you need to have no obstructions in your "line of sight" (to the satellites). With obstructions your GPSr accuracy is highly likely to be degraded.

 

When WAAS signals are being received you will notice a "D" in the signal bars. "D" represents differential data and indicates that possible corrections are being made to your non-WAAS satellite data.

 

If you are using your unit for geocaching in the usual locations that caches are placed - WAAS represents no value (and as you note extra battery consumption).

 

Unless you are landing large airplanes in compromising conditions I would leave WAAS off.

Not unless you consider about 30 degrees above the horizon (average in the US) to be "low". I have seen WAAS working well under tree cover with a high sensitvity receiver. And the power "drain" is minimal as noted above....

[+Barnie's Band of Gold]

...WAAS satellites are geo-stationary and usually very low on the horizon. To get the most effective use from them you need to have no obstructions in your "line of sight" (to the satellites). With obstructions your GPSr accuracy is highly likely to be degraded.

 

When WAAS signals are being received you will notice a "D" in the signal bars. "D" represents differential data and indicates that possible corrections are being made to your non-WAAS satellite data.

 

If you are using your unit for geocaching in the usual locations that caches are placed - WAAS represents no value (and as you note extra battery consumption).

 

Unless you are landing large airplanes in compromising conditions I would leave WAAS off.

Not unless you consider about 30 degrees above the horizon (average in the US) to be "low". I have seen WAAS working well under tree cover with a high sensitvity receiver. And the power "drain" is minimal as noted above....

I don't think it is appropriate to apply an "average" to the position of the WAAS satelitte for a US user. The consideration is "relative" to where the user is. For example, a user in Southern Florida will find that the WAAS satelitte (ID #35) is very high on the horizon and is likely to get a good signal in almost all conditions. On the other hand a user in Northern New York state is going to find the same WAAS satelitte very low on the horizon. A good signal for him will occur only if he is on a terrain peak or on a very large body of water (assuming the North end of it).

 

While the average position of 30 degrees above the horizon may be quite true - this average does nothing for the real life experience for those facing a WAAS satelitte that is low (to them) on the horizon.

 

While WAAS is a good technology for what it was designed for, it is not the benefitial in all cases.

[+fizzymagic]

WAAS satellites are geo-stationary and usually very low on the horizon. To get the most effective use from them you need to have no obstructions in your "line of sight" (to the satellites). With obstructions your GPSr accuracy is highly likely to be degraded.

Incorrect. Unless you are in northern Alaska, the WAAS satellites are quite visible. In Maine, for example, satellite #51 has an elevation of 26 degrees.

 

Prior to last year, there was poor WAAS reception in the Northwest because the satellites were too far east and west (not south). That has since been corrected by the addition of new WAAS satellites and the movement of satellite 35.

 

If you are using your unit for geocaching in the usual locations that caches are placed - WAAS represents no value (and as you note extra battery consumption).

Incorrect. WAAS accuracy can be quite helpful in geocaching. In modern units, WAAS corrections do not impact battery life; even in the older ones it was minimal.

 

Unless you are landing large airplanes in compromising conditions I would leave WAAS off.

I would suggest you not make suggestions based on misinformation.

[+Renegade Knight]

I never get a straight answer when asking about WAAS.

 

If I set it on, I lose some battery power and it might be for nothing.

 

How do I tell if I would benefit from having it on. What is the D in my bars telling me. ...

 

The D tells you that the satalites signal is being Differentially Corrected. Same idea as what surveyors who use GPS to survey do. That's what WAAS does. Provides a differential correction to your GPS.

 

As I understand it (and I can be wrong) Garmins use a separate circuit for WAAS. Meaning since you can turn it on and off it uses some power, and also uses some of your units processing power. I notice a difference in processing speed and updates on my GPS V (much older GPS than your own). The newer GPSs are faster. You may not notice a processing speed hit.

 

With some early Magellans (and maybe all the newer ones) WAAS was always on. Even if you turned it off the circuit was still running, you just weren't getting the WAAS info so there was no battery savings to be had.

 

As for WAAS helping your location. When I first turned it on, it seemed to make things worse so I turned it off. Once I turned it on and forgot. After a spell I noticed it on and my EPE reported single digit accuracy. That was the first time I'd seen that with my GPS. It makes a difference though it seems like when you first start using it you have to let it work at things for awhile to see all the benefits.

 

I'd trust Fizzy's answers over my own.

Edited September 18, 2008 by Renegade Knight

[+trainlove]

Some might tell you that WAAS eats up battery power. No, it's just 2 more channels inside your GPSr.

Losing power will not 'screw' up anything. But with some if not all Magellans, a master memory reset will forever lose WAAS capability for you since Magellan had hardprogrammed what WAAS satellites it knew about several years ago into firmware that's being used today. Not so for Garmins since they do a search for all possible WAAS PRN codes if they can't see a WAAS satellite. I.E. Garmin engineers are real engineers, Magellan people never got out of kindergarten.

 

Some of the answers in my thread http://forums.Groundspeak.com/GC/index.php?showtopic=185052 might be the confusion you are refering to. also refer to http://ray.jerome.jobs.googlepages.com/majormagellanproblem for all I know on the topic as it relates to Magellan.

Edited September 19, 2008 by trainlove

[+Stu The Hiker UK]

The way I look at WAAS is like this....

 

If I have it turned off I get 20 hours out of my batteries in my etrex H

If I have it turned on I get 17 hours

 

So I keep it turned on and always have spare batteries anyway

 

Maybe I should get some sleep before i make anymore posts

Edited September 20, 2008 by stuthehiker

[+Redwoods Mtn Biker]

Anyone have a link to a map showing the geostationary position of the WAAS birds?

[+user13371]

Anyone have a link to a map showing the geostationary position of the WAAS birds?

http://en.wikipedia.org/wiki/Image:FAA_WAA..._generation.jpg

 

See also http://en.wikipedia.org/wiki/WAAS

[+user13371]

...with some if not all Magellans, a master memory reset will forever lose WAAS capability...

Hey, I understand this bothers you -- as you have one of the affected receivers, but ...

 

Implying that ALL Magellan receivers have this problem and the suggestion that Magellan's engineers are (were) stupid is just wrong. And you try to work this into some, if not all of your posts. Couldn't you just say "I've written about this before, here's a link" and leave it at that?

[+trainlove]

If I have it turned on I get 20 hours out of my batteries in my etrex H

If I have it turned off I get 17 hours

 

So perhaps it's a perpetual motion machine? Or more than 100% efficiency? I thought you got them backwards but then your next sentence confirmed you said what you mean.

[+Stu The Hiker UK]

If I have it turned on I get 20 hours out of my batteries in my etrex H

If I have it turned off I get 17 hours

 

So perhaps it's a perpetual motion machine? Or more than 100% efficiency? I thought you got them backwards but then your next sentence confirmed you said what you mean.

 

I got them in the wrong order, I blame lack of sleep

[+coggins]

Anyone have a link to a map showing the geostationary position of the WAAS birds?

First off, unlike the dedicated GNSS satellites, there is no such thing as a WAAS satellite. There are communication satellites in geostationary orbit that happen to broadcast the SBAS signal @ 1575.42 MHz. This is like calling them the Fox Sports satellite or the CBC satellite. Not long ago, WAAS signals were broadcast on Immersats, but the lease expired and the satellite were moved. Here is some information for North America:

 

NMEA #48 / PRN #135

Galaxy 15 at 133.0°W tracker

Galaxy 15 at 133.0°W Frequency chart

 

NMEA #51 / PRN #138

Anik F1R at 107.3°W tracker

Anik F1R at 107.3°W Frequency chart

 

On the tracker page, you can click your approximent current location on the map to find the forward azimuth and elevation of either satellite. Also you can mark a waypoint in your GPSr to project a forward azimuth to the satellite (if your skyview page doesn't do it for you).

Edited September 20, 2008 by coggins

[+trainlove]

First off, unlike the dedicated GNSS satellites, there is no such thing as a WAAS satellite.

 

True.

And then again everyone seems to call the SBAS system WAAS when really it's Satellite Based Augmentation System, and WAAS, EGNOS, MSAS and a few other proposed ones are just a part of it.

 

The orbital elements of them can be found at sites in the link I previously posted. Plugging those elements into a satellite tracking program can 'show' you where they are.

You also can possibly see where they are using the www.heavens-above.com web site which is just great.

[+coggins]

The orbital elements of them can be found at sites in the link I previously posted.

Didn't see them, looks like some sort of Magellan WAAS thread.

[+coggins]

Anyone have a link to a map showing the geostationary position of the WAAS birds?

Here ya' go. Asheville NC, WAAS Skyplot:

[+Mudfrog]

I've had three Garmin units that offered waas capability and have tried using it on all of them. I never saw any improvement when geocaching and actually thought i was getting run around in circles a few times when using it, so have always went back to leaving it turned off. I admit that i haven't given my newest 76cx a good college try but i see absolutely no reason to since it does such a good job getting me to ground zero without it. For me, having waas turned on provides no noticeable benefit and seeing battery life extend with it off, even if it only turned out to be a few minutes, is worth it.

Edited September 21, 2008 by Mudfrog