Thread: Garmin Etrex GPS ??

G'Day Gang,
Well I now have my Etrex "Yellow". Very happy with it so far , Ive even got a book about GPS from the libaray by Robert Pepper, better still its Aussie and easy to read ! (just noted in past posts that this book was the "one to get").....but Ive got a Question.

In the "set up" menu and then into "units" Im wondering what settings I need to put in. mainly "Position Format" & "Map Datum". I dont think the guy I got it from used it much and really had no idea.

Ive got the rest sorted but Im just making sure what they should be on.....any help please?

Also Im surpried that i still can use the etrex while dtill in the Disco....well not as good as out of the Disco but still can be used. Ive also noted that it really east the recharable batteries quickly, not a big prob but thought I would get more out of them.

Originally Posted by amshaw

G'Day Gang,
Well I now have my Etrex "Yellow". Very happy with it so far , Ive even got a book about GPS from the libaray by Robert Pepper, better still its Aussie and easy to read !

Robert is a moderator of the GPS forums here :P

Position format and datum need to be set to whatever the map your using with your GPS uses.

I prefer UTM for position format though.

The map datum needs to be set for each map otherwise the position your GPS tells you and the position you see on the map won't match up with the actual position on Earth.

However if you just use your GPS to show you a line on the screen and getting back to waypoints you've already marked or vehicle speed etc then they are irrelevant.

Originally Posted by incisor

Robert is a moderator of the GPS forums here :P

Just as well i said its a really really great book isnt it

Originally Posted by Utemad

Position format and datum need to be set to whatever the map your using with your GPS uses.

I prefer UTM for position format though.

The map datum needs to be set for each map otherwise the position your GPS tells you and the position you see on the map won't match up with the actual position on Earth.

However if you just use your GPS to show you a line on the screen and getting back to waypoints you've already marked or vehicle speed etc then they are irrelevant.

Hi All,
Ive been playing again, but I just dont get it, I mean when trying to use my location Im having trouble finding that possie on the map.

Im using the Vic CFA fire map book, we use a 6 number map referance. Any idea what setting I need to have my gps on so I can use it with my maps?

I know on the gps in the CFA command 4x4 it gives two (of course) 7-8 numbers (Nthings & Eastings), from memory we need to take off the first & last two of each number to get our possie, do i need to do the same?

Any help would be great please

I think you need to set your GPS to UTM (Universal Transverse Mercator) which I'll explain why below.

I'll use my HEMA Fraser Island map as an example as it sounds to me to be using the same system as your Vic CFA maps. Most large scale maps use this as you don'e have to worry about the curve of the Earth at such a large scale.

UTM uses 6 numbers for an easting and 7 for a northing. However when you look on your map only some of the numbers will change so they only show you the numbers that change. So on my Fraser map the bottom left corner is

490000E 7150000N

So as you go further up the left hand border of the map instead of displaying the entire northing again they just display the big number as the rest stays the same. So all you will see is 55, 60, 65, 70 etc until it reaches 00 again and you will see 7200. The same goes for the eastings.

Ok Thankyou Will try that....umm Just changed it to UTM but there are to choose from;

Aus geod '66
Aus geod '84

Also I got this reading out the front of our place (As per screen);

54H 0588610
UTM 5822687

Any ideas?

am I on the right track, just about to pull out the map book.

Given your coordinates I would place you slightly North-West inside of Hamilton, Vic. You've stated Hamilton as your location though of course
54H is the zone (see the websites below)
0588610 is the Easting
5822687 is the Northing

The GPS has just added a 0 to the front of your Easting.

As for your Aus geod '66 and Aus geod '84 did you get them from your map or the GPS?

When inputing these settings under 'Position Format' choose 'UTM UPS'.
Under 'Map Datum' choose either 'Aus geod '66' or 'Aus geod '84'. Whichever is stated on your map book.
These are the menu setting names in my Etrex Legend (blue one). Not sure if they differ from the standard Etrex (yellow).

To get your position I used Oziexplorer and some maps I recently downloaded. They are Vic CFA maps. There are about 448 maps. When on the map sheet that incorporates Hamilton (map 431) it says for greater detail of Hamilton see map 431k on page 151. Is this the same map book you are using? These look to be very high quality scans of the book or perhaps they were digital to start with?

Have a look at these sites to get a better understanding of UTM.
http://www.dmap.co.uk/utmworld.htm
http://www.maptools.com/UsingUTM/UTMdetails.html