Garmin Handhelds

[revrnd]

Can someone tell me where Garmin explains the circle of varying size on the map screen?

 

My 10 year old nephew asked me about it when we were using my Legend Cx (I've seen it on my previous units too). I told him it had something to do w/ the accuracy of the signal. I dug out my owners manual, but couldn't find anything. He the type of kid that expects a more exact answer than a vague 1 & is quick to tell me I don't know what I'm talking about .

[+Indotguy]

On my Lowrance those are called range rings and indicate distances which vary with zoom level. I don't know anything about Garmins, sorry.

[dogwalkers2]

Can someone tell me where Garmin explains the circle of varying size on the map screen?

 

My 10 year old nephew asked me about it when we were using my Legend Cx (I've seen it on my previous units too). I told him it had something to do w/ the accuracy of the signal. I dug out my owners manual, but couldn't find anything. He the type of kid that expects a more exact answer than a vague 1 & is quick to tell me I don't know what I'm talking about .

Garmin's FAQ page on their website (search for accuracy circle) says the following:

 

Question: What is the circle around my position on the map?

 

Answer:

This is the "Accuracy Circle". This circle represents the approximate accuracy of the GPS position based on the Estimated Position Error (EPE) and the map data quality. The position of the GPS device on the map should be located somewhere within this circle. This feature can be turned on or off on the GPS device. Please refer to the owner's manual for instructions in doing this.

[BF Hammer]

I don't know where to get Garmin's official answer, but I can explain it.

 

The circle represents the error factor. The gpsr thinks you are at the triangular spot it shows, but since the positional accuracy is not exact, the circle represents that your real position could be anywhere within that circle. (related to signal strength and number of satellites visible to the gpsr).

[O-Mega]

If its on the actual map screen, it may be a part of the distance measurement tool. It pops up to encompass the area from the centre point out to the distance you marked (say 360 from center out to 5 miles etc).

 

v/r

O-Mega

 

Edit to add: The above answer message is correct on some Garmins, on my 60csx it is not there. The only ring is on the satellite screen and the measurement tool.

Edited January 3, 2008 by O-Mega

[QuigleyJones]

Edit to add: The above answer message is correct on some Garmins, on my 60csx it is not there.

It is on mine, didnt know you could turn it off. will have to look into that.

[robertlipe]

The FAQ pinned at the top of this group explains the blue circle on the Garmin GPS.

 

The 60csx also has this same blue circle on the screen. You don't see it in normal use unless you're zoomed in crazy far on the map and/or in an area of poor reception.

[Big Yac]

how would I turn off the accuracy ring on a germin legend? I cant find it in the manual

[Haymarket]

My 60CSx shows the blue ring on the map, but it doesn't seem to correlate to accuracy, as the sat page says I have +-16ft accuracy, and the blue ring is .2 miles from my current location. What is the deal with that?

[Hertzog]

Edit to add: The above answer message is correct on some Garmins, on my 60csx it is not there.

It is on mine, didnt know you could turn it off. will have to look into that.

You can't turn it off indenpendently, but if you use the "lock on roads" setting it goes away. (This applies to the old Vista, 60CS and 60CSx; it's possible they have made it possible to turn it off on some of the other models - should be simple enough, and a lot of people don't like it - but I doubt it.) I personally like it - gives you a good idea of how much to trust your displayed position - but each to his own.

[Hertzog]

My 60CSx shows the blue ring on the map, but it doesn't seem to correlate to accuracy, as the sat page says I have +-16ft accuracy, and the blue ring is .2 miles from my current location. What is the deal with that?

The radius of the circle is about 3.4 times greater than the accuracy number - apparently to go from about a 50% confidence level to a 99% (Garmin doesn't say exactly what they are doing, but this seems to make sense). They also add in an extra error to account for the inaccuracy of whatever map is being used. You can see this if you switch to the basemap; there the map error dominates and the circle gets very large (0.2 miles is what you get with the basemap).

Edited January 3, 2008 by Hertzog