Robin posted:

Forgot - similarly at home , bang waypoints into one of the many free gps programs and change datum.

Someone may also remember tag for a so constructed XL spreadsheet that did this

The Explorer posted:

You are both confusing the terminology (which is not good with a subject that can be confusing enough)

AGD doesnt = UTM nor does it "conform" with WGS84 .

In simple terms (AFAIK)
Latitude/longitude and UTM (Universal Transverse Mercator) are terms that refer to the coordinate system being used i.e Degrees, minutes, seconds (for lat/long) or metres (UTM).

WGS84, AGD84, GDA94 etc are datums i.e. reference points within the earth from which the coordinate systems are measured/originate from. You can use any datum with any coordinate system, as long as you let people know what datum you are using when you pass the coords on.

Today, in Australia, GDA is used as the datum when creating new maps (well it should be). The GDA94 datum closely approximates WGS84 and both can be considered equal for navigation purposes. Maps that utilise GDA datum and UTM produce a coordinate grid referred to as the Map Grid of Australia (MGA). Prior to that Australian maps were produced using the AGD84 (or 66) datum. Maps that utilise AGD and UTM produce a coordinate grid referred to as the Australian Map Grid (AMG). There are still many maps sold using the older AGD84 or 66 system which can of course cause problems as there is a difference of about 200metres between coordinates numbers created using AGD and GDA.

John – its is unclear from your original post whether you want to convert WGS84 coords to AGD (though I suspect you mean GDA, in which case no conversion is required) or if you wish to convert lat/long (degrees etc) coords to UTM (metres) coords…..or both??

Cheers
Greg

Robin posted:

Hi John

Agree totally with Greg , and probably should have been clearer myself.
The methods I described works for both co-ord and datums.

But we probably should add that the datum conversion issue is a minor adjustment usually 100 whatever meters , co-ord conversion between lat/lon and UTM is between degrees and meters .

Hopefully someone here can help with your specific GPS , usually to change either is under a setup menu sometimes called navigation

Robin Miller

The Explorer posted:

It may not be this simple...but if you want to get UTM coords on your screen

To set the coordinate format

Press the Page button on your GPS receiver until the Menu screen appears.
Select System Setup.
Select Coordinate System.
Select UTM from List.

I dont know what datum the maps you have are...but

To set the datum

Press the Page button on your GPS receiver until the Menu screen appears.
Select System Setup.
Select Map Datum.
Select datum you want to use from List.

Keep in mind that WGS84 is the same as GDA94 (well so close it dont matter) - the MLR SP24 probably doesnt have GDA94 so just use WGS84 in its place. The maps you have may use AGD84 or 66 - this should be on datum list in GPS.

Cheers
Greg

Member - John L G posted:

Hi Robin & Greg,

Well how easy was that.

Had a play just now and lo and behold the GPS now shows the new format so all I have to do now is go and have a play in the bush.

Many many thanks

John G