Jump to content

Accuracy: 7 feet? Wow! How?


Krenath
Followers 0

Recommended Posts

Just recently, my GPS has started displaying accuracies below 10 feet. Sometimes for long periods.

 

Not that I'm complaining or anything, but I'm curious: Has anything changed/happened recently that would have resulted in even more accuracy from WAAS enebled GPSrs?

 

Oh, and what do the Ds in the signal strength bars on the satellite page indicate? The Venture owner's manual is rather sparse on detail.

Link to comment

Along these lines, I am thinking of buying the yellow eTrex and on another form someone posted they were getting readings within 100feet and he searched from there. I'm using a palm pilot with a GPS companion and normally get to within 10 feet or better. Is 100 feet really the norm. with the eTrex?

 

---I will stand out, I am a raven in the snow.

Link to comment

For the first time today I tried my new external antenna on the roof of my car hooked to my GPS V. Not only did it lock on 10 of the 12 birds, but it locked up WAAS (Differential, the "D") and maxed out at a 6 foot accuracy. The best I ever got with the built in antenna was 10 foot, which I would assume was due to me casting my body shadow on some of the birds while holding the unit.

-Centaur

Link to comment

My 7 foot lock was with the Etrex Venture, the unit's own internal unit, and while it was sitting on the dashboard of my car. My car does have a steeply-sloping windscreen, which could have given the GPSr a nice wide field of view. Up to six birds were dusplaying Ds at any given time, some even when signal strength data wasn't displaying at all.

 

I don't even own an external antenna, nor would I know how to connect one to a Venture, if it's even possible.

Link to comment

Yes, I can often get 7' or 6' accuracy reading with a good WAAS lock. But your accuracy reading is doing nothing more than telling you how good it thinks it is doing. Think of it this way: your GPSR is saying ''we think you are somewhere within this range 90% of the time''. It is not gospel. The other day I stood on a known position and the accuracy reading was 68' but the unit told me I was 5' from the target. The accruacy reading dropped to 24' and the unit said I was dead on the target. A week or so ago I had an accuracy reading of 7' and the unit said I was 3' from the target. In all cases the accuracy reading was right! I was within that range. It just wasn't sure how sure it was.

 

Yes, the D's mean that, that satellite is using WAAS augmentation.

 

4497_300.jpg

Link to comment

I also got my first sub 10' reading this past weekend. I was surprised as it usually was in the 15-25' range most of the time. It is like something changed, not that the accuracy was that much closer when I was looking for a cache, but I was surprised to see a number that low.

 

Dave

 

[This message was edited by Dave Jousma on August 21, 2002 at 04:40 AM.]

Link to comment

For what it's worth, I've seen "accuracy" (I assume they use this term on the newer eTrexi rather than "EPE") readings as low as 7ft (standing still a while in an open field with WAAS) on my eTrex Legend. A friend of mine (who owns an eTrex Vista) says he's seen it as low as 5ft.

 

df

Link to comment

I was kinda wondering this same thing myself. I have repeatedly tried WAAS on my Etrex Legend but even going up an 80' tower here in Florida couldn't get any accuracy readings under 13 or 14 feet.

 

I also read that with the Beta C release it was supposed to help and now after installing the software, I'm down to 6 to 7 ft. I didn't know if it was the software or if something else has been changed but I LIKE IT!

 

The Lone Ranger

Link to comment

quote:
Originally posted by Anders:

Garmin stated something about that they had updated the calculation of the EPE when receiving WAAS signals in the latest releases for the Legend.

 

Anders


 

Yes, here it is:

 

eTrex Legend Version 2.40b to 2.40c BETA Differences:

 

Improved accuracy for WAAS EPE.

Made map setup restore defaults set to land mode.

Improved map selection capabilities of city searches.

Set zoom in and zoom out keys to page through some lists.

 

[This message was edited by EraSeek on August 20, 2002 at 08:57 AM.]

Link to comment

Typical accuracy (viewed on screen) for my yellow etrex has been 15 ft lately with 5-10 birds normally visible in my area. Seems like every year the accuracy seems to get a little better. Recently, we were in northern Mannitoba on a large lake. I was getting signal from all 12 birds routinely and the associated accuracy was 10 feet. That's great as this lake is loaded with undrwater hazards (rocks) which can send you home early! The yellow etrex performed just as well as the Lowrance GlobalMap100 a buddy of mine had on board

Link to comment

This week I started to see my Venture claim to be down to 7 feet. Previously I had only seen 15 foot accuracy. I had attributed it to a firmware update. Couldn't see anything reported on any WAAS-related web pages as recent new and improved.

 

max

Just visiting this planet

Link to comment

It's my understanding that your actual accuracy hasn't changed, only the reporting of it. You may have had 7' accuracy in the past, but if your unit isn't reporting that fact correctly to you, it's of no use to you. The firmware fixed the inaccurate 'reporting', not an inaccurate signal.

 

Greg

N 39° 54.705'

W 77° 33.137'

Link to comment

I suppose the nice thing about software fixes is "things" can be fixed and I suppose if "things" don't sound right next week then lets have another go.

 

Cynical I know icon_wink.gif but there's really no consistency to EPE type stuff if last week it was that and this week is can be this icon_biggrin.gif.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

Link to comment

I suppose the nice thing about software fixes is "things" can be fixed and I suppose if "things" don't sound right next week then lets have another go.

 

Cynical I know icon_wink.gif but there's really no consistency to EPE type stuff if last week it was that and this week is can be this icon_biggrin.gif.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

Link to comment

I noticed the accuracy change with my Venture when I updated the firmware awhile back, but one thing that puzzles me is that I get better signal and better accuracy in the car when traveling traveling at high speeds.

 

Last time I noticed this I had 11 birds and 7' accuracy while traveling 70mph.

 

When walking/hiking, I usually get between 6-8 birds but 15-17' accuracy. Could it be that they track better when moving faster?

 

TEAM SHIBBY!!!!

 

Krs, Kar & Na

Link to comment

quote:
Originally posted by gnbrotz:

It's my understanding that your actual accuracy hasn't changed, only the reporting of it. You may have had 7' accuracy in the past, but if your unit isn't reporting that fact correctly to you, it's of no use to you. The firmware fixed the inaccurate 'reporting', not an inaccurate signal.

 

Greg

N 39° 54.705'

W 77° 33.137'


 

Looks like the manufacturer is trying to improve his marketability. Which would you buy, a unit that has an EPE regularly of 18' or one with 8'?

 

The accuracy hasn't changed, only the image. The formulars for determining you position hasnt changes, your GPSr hasn't changed so the only thing that clould make a "real" accuracy differecnt would be if the birds are transmitting stronger signals, I suppose.

 

I created cache at a benchmark at the end of 2001. Finders posted what their GPS were reading at the benchmark. 12 of 18 were under 12 feet with many different models. My own Vista was off 1 meter with Waas and an EPE of around 16 and about 3 meters off without Waas and an EPE of 19 or so.

Link to comment

quote:
Originally posted by Team Shibby:

I noticed the accuracy change with my Venture when I updated the firmware awhile back, but one thing that puzzles me is that I get better signal and better accuracy in the car when traveling traveling at high speeds.

 

Last time I noticed this I had 11 birds and 7' accuracy while traveling 70mph.

 

When walking/hiking, I usually get between 6-8 birds but 15-17' accuracy. Could it be that they track better when moving faster?

 

http://www.teamshibby.com

 

Krs, Kar & Na


 

I would think you would get however many birds where visible whenever, and not much will affect or improve that; But I have read that the accuracy of your position is actually improved by a moving unit rather than a static one. I forget why...an added doppler effect I would guess.

 

4497_300.jpg

Link to comment

quote:
Originally posted by Kevin & Susan:

According to our new GPS V's manual: ''When WAAS is enabled, you will see WAAS satellite numbers, beginning at 33 or above, displayed on the Satellite Status Page. When correction data is received, a "D" will appear in the Satellite Status Page signal bars for all applicable satellites.''


 

For those of us in the USA, it's sat. #35 on the East and I think #42 for the West.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Followers 0
×
×
  • Create New...