Waas?

[Veritech]

To Waas or not to Waas? That is the question.

 

I am new to Geo caching and am going to be getting my first GPS very soon. Have been doing a lot of research on what one to get and I am uncertain if I need to pay the extra $$$ for a unit with Waas.

 

Also since I live in Michigan and Waas is only available in the USA, how much more accurate will it be up here?

 

TIA,

Randy

[+zenrandom]

your mileage will vary. If you are going to use the gps under tree cover, you'll almost never get a waas signal worth anything. To get a waas signal you are going to want a nearly completely clear unobstructed view of the southeastern sky for that waas bird. There may be more in the future, I believe they have said up to 19 waas satellites... I find waas nice for standing around just to know where I am *really* accurately but don't bother looking for it to come in when I'm hunting a cache. garmin has a really good description of waas here... http://www.garmin.com/aboutGPS/waas.html

 

-zr

 

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If it ain't broke, I can *fix* that...

[+EraSeek]

To WAAS or not to WAAS. Well, WAAS will eat batteries quicker. Waas will get you closer to a known mark if you have good exposure to the WAAS sat. I think you can only get #35 where you are. WAAS only improves things if things need improvement. Mostly it corrects for ionoshphere fluctuations which causes signal delay, which throws off timing, which throws off your coordinates. These fluctuations are a bit more prominate in the south than the north. Your improvement in everyday terms, with a good fix, will take you probably from 12' away to 3' away. If you don't have a good fix, it won't give you the data you need anyway. I use WAAS to go ''OOO'' and ''AHH'', and I also use it when planting a cache to get a good coordinate reading.

 

Do you need it? No. Do you want it? Maybe.

 

[The Real McCoys]

I purchaced my like new ETREX Legend in April on EBay for $170 (it still had the plastic cover over the screen), it has WAAS and I love it. If I would have had buy it at list price I might have not gotten one with WAAS, but because I found a deal I bought it and love it. I don't always get a WAAS satellite but when I do I can get a position fix of within 10 feet.

[The Real McCoys]

I purchaced my like new ETREX Legend in April on EBay for $170 (it still had the plastic cover over the screen), it has WAAS and I love it. If I would have had buy it at list price I might have not gotten one with WAAS, but because I found a deal I bought it and love it. I don't always get a WAAS satellite but when I do I can get a position fix of within 10 feet.

[+apersson850]

I haven't WAAS'ed in on any cache so far, since I'm in Europe. Works anyway.

 

If they could let the WAAS correction last a little longer in the unit, when the WAAS bird is lost, it would be possible to WAAS it up in the open, then run around using the last WAAS fumes in the woods for a little while.

 

On the other hand, multipath, obstructions etc. may induce more errors among the leaves than WAAS removes...

 

Anders

[ejmct]

This topic was enlightening because I always thought that WAAS was that radio station in Cincinatti where Venus Flytrap & Dr. Johnny Fever worked

 

Seriously, when I see those little "D's" on the satellite page of my Vista that means I'm getting WAAS-ed?

 

I see that fairly frequently when I'm in the car.

[ejmct]

This topic was enlightening because I always thought that WAAS was that radio station in Cincinatti where Venus Flytrap & Dr. Johnny Fever worked

 

Seriously, when I see those little "D's" on the satellite page of my Vista that means I'm getting WAAS-ed?

 

I see that fairly frequently when I'm in the car.

[Timothius]

I have tried WAAS several times, and on several trips with my legend, and have had lots of those little D's in the power bar and have not seen any improvement. If fact there were a few times when I started out with 10-12 foot accuracy and after turning on the WAAS it jumped up to 30 feet accuracy. Maybe when it jumped up it really did get more accurate. I just haven't seen anything to make it a big seller in my book. It may be my location, but I think it's just a bunch of hype right now!

 

An Irish Toast:

"May you be in heaven a half hour before

the Devil knows you're dead"

[Veritech]

Thanks for all the replies. It looks like getting a WAAS receiver is an option at this point and not a requirment.

 

Now I will make the determination on what GPS to get by price and featured instead of just WAAS.

 

I have narrowed the list down to the following:

 

1. Garmin GPSMAP76 (waas enabled)

2. Garmin GPS III+ (I like this one as I could use it on my ultralight with an enternal antena.

 

3. Garmin Etrex Legend (waas enabled)

4. Magellan Sporttrax map (Also waas enabled)

 

Any input on these choices?

 

Thanks,

Randy

[ejmct]

On my way into work this morning I had the D's and my accuracy was 20-30 feet, which is pretty typical even when I am not getting any WAAS signal.

[+ApK]

quote:

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Originally posted by ejmct:

 

Seriously, when I see those little "D's" on the satellite page of my Vista that means I'm getting WAAS-ed?

 

---

 

Yes, unless you happen to have a Differential GPS system attached....that'll give the D's, too.

[+apersson850]

Note that in the most recent releases of firmware for the Legend and Vista (and others, perhaps?) then estimated error calculation when receiving WAAS signals has been updated, to better reflect the reality.

 

I think it seems like it's more optimistic about the ordinary EPE too.

 

Anders

[+zenrandom]

I have seen EPE as good as 6' with WAAS enabled on my Legend. I'll take accuracy of <2m any day.

woo

 

On the other hand, i have seen EPE degrade significantly while I'm still in the process of gaining differential corrections for my satellite locks. i.e. had EPE of 16' without differentials, acquired a few differentials, EPE jumps to 30'. I just let it settle a minute or two. Which seems to be the really important thing with WAAS on the ground. Stop moving around so much! I'm sure it's just peachy in the air.

 

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If it ain't broke, I can *fix* that...

[+Criminal]

Here in Washington I can park my truck on McChord AFB in a certain area and get sat #47. When I come out at lunch after leaving it turned on and running off the truck battery, I will see 8' EPEs. As soon as I start moving it goes back to around 18'. That's still not too bad.

 

If your house catches afire, and there aint no water around,

If your house catches afire, and there aint no water around,

Throw your jelly out the window; let the dog-gone shack burn down.

**Huddie Ledbetter**

[+EraSeek]

Listen, don't pay so much attention to your accuracy (or EPE) reading. I have stood on a NGS marker before,many times, and checked this. When you switch over to WAAS, often your accuracy reading shoots way up before dropping back down. Not sure why it does this (mostly because it is still aquiring needed data), but with D's up and an EPE of like 30' to 60' I had much the same results as when the EPE dropped down to 7'. And that is that I was within a few feet of the correct postion with the distance to target reading on my GPSr both times with WAAS enabled. This is a known postion. So think of it this way; your EPE or accuracy reading is saying ''I am 90% sure that your target position is within this range 90% of the time.'' Thus both times I was within a few feet of the target, and both times it was within that range, even though the range readings varied. It was still right both times.

 

EPE or Accuracy readings are there to give you an idea of how well your GPSr thinks it is doing with the signal and resulting accuracy. It is not gospel! Usually your actual postion will actually be better than that EPE reading. Waas or not, I've usually seen it about 40% better when I have checked it. But 10% of the time it may be quite wrong.