GPS dgps vs. waas

[Troller]

I know their is a difference between the two but they seem like they do the same thing. Is their any advantage of one over the other.

[Myles]

For an explanation check out this site, click on about GPS for a quick answer.

http://www.gps4fun.com/index_main_advice.html

Don't have too much fun there.

myles

[Troller]

Thanks myles waas appears to be accurate less than 3 meters. dgps accurate 3 -5 meters. dgps requires a antenna . cant find if waas requires an extra antenna.

[pirk fan]

waas capable gps units don't require any additional hardware, but the stations are not available everywhere.

[burliest]

From my perspective:

You don't need either but WAAS is standard on many units now. I mean from my experience, my garmin always gets me within spitting distance (maybe a pebble throw). I guess I have just never had to position my boat exactly over the top of anything that small.

GPS accuracy used to be about 100 yards and usually better from my experience. Even then it always got me between the jetties in fog and close enough to a fishing hole. I always found the hole even if it was a real teeny-tiny one by using the fish finder.

DGPS (Differential GPS) used to be a benefit because it reduced or "corrected" the error to a few yards. DGPS was (still?) transmitted over FM signals and you are therefore limited in many areas. It was also a subscription like a pager (in fact uses the same technology) and was about $50 a month when I checked into it a few years ago.

The difference now is that the military, just a year or two ago, removed the purposely introduced random errors (called SA or Selective Availability) from the GPS system and it rendered DPGS useless. DGPS is kind of like ocean front property in Arizona. I am sure someone will be glad to sell the service. Gosh, I wonder if anybody is still paying for it or if it is even still available.

WAAS does claim to increase accuracy from 15 meters to 3 meters and it appears to be free so why not?

I hope that was useful.