A question about WAAS

[+IGJoe]

I know what WAAS is and I knew my GPSr was WAAS capable HOWEVER I've been using for the last 8 months with the WAAS disabled. Needless to say I never really read the instruction manual (insert typical guy comment here) and last weekend, while playing around with the main menu, I discoverd ' Hey, my WAAS is disabled.'

 

The question 'Is there a downside to using WAAS'. I'm surprised something that optimizes performance was not turned on as a default.

[+EraSeek]

Uses more processing power therefore perhaps some minimal battery drain and perhaps some increased lag in redrawing your map screen.

 

I leave it on.

[+Prime Suspect]

I know what WAAS is and I knew my GPSr was WAAS capable HOWEVER I've been using for the last 8 months with the WAAS disabled. Needless to say I never really read the instruction manual (insert typical guy comment here) and last weekend, while playing around with the main menu, I discoverd ' Hey, my WAAS is disabled.'

 

The question 'Is there a downside to using WAAS'. I'm surprised something that optimizes performance was not turned on as a default.

There's no one answer. Depends somewhat on what GPS you have, and where you live. If you usually have a good view of one of the two satellites that supply WAAS info, then maybe yes. If you have an older GPS, then maybe no, as they tended to switch over to the WAAS enhanced birds once they got a certain minimum, regardless of whether or not they resulted in a better solution. Newer GPSs are much more intelligent about handling WAAS enabled signals, so there's not much downside in leaving it on, except the slight additional power use.

Edited August 15, 2006 by Prime Suspect

[+James Lobb]

is WAAS in the USA only (sorry if i sound like an idiot, i never understood it fully)

[+pbn]

is WAAS in the USA only (sorry if i sound like an idiot, i never understood it fully)

No, the technique will be established around the globe (as far as I understand). In Europe the same thing is called, by the acronym, EGNOS and has been launched for active service during this summer. In Asia the same thing is/will be called something else.

 

You can read more on these pages:

- http://gpsinformation.net/exe/waas.html,

- http://gpsinformation.net/waasgps.htm and

- http://www.gpsinformation.org/dale/dgps.htm

(and several more places I am sure)

 

Here in Sweden I often receive two different EGNOS satellites. (The satellites that Garmin numbers 33 and 37. I believe that these satellite numbers are GPSr manufacturer specific.)

[+Prime Suspect]

The Asian system is called MSAS (Multi-functional Satellite Augmentation System).

 

And if it's not obvious by the territorial nature of these satellites, they are (unlike the regular GPS satellites) geostationary.

Edited August 15, 2006 by Prime Suspect

[+StarBrand]

I leave it on all the time. I have noticed my batteries don't last quite as long but it is minimal - 16+ or so hours with WAAS on - 17 to 18 with it off.

[+EraSeek]

is WAAS in the USA only (sorry if i sound like an idiot, i never understood it fully)

 

That depends. WAAS is a US based system of corrections. Other regions of the world have implimented their versions, and some feed off the US system.

 

WAAS has 2 factors that apply to your question. The WAAS corrects these errors:

 

Ionosphere

Clock

Ephemeris

 

The ionosphere coorections are based on a grid system monitored and corrected for generally most of north America, and thus you must be within this area for the corrections to be meaningfull.

 

The clock and postion errors are not restricted by this local grid as long as you can see a WAAS sat, so those corrections can be used outside of the US grid if your GPS allows it.

[+pbn]

(The satellites that Garmin numbers 33 and 37. I believe that these satellite numbers are GPSr manufacturer specific.)

I was wrong about these satellite numbers, they are NMEA satellite IDs.