Difference between WGS84 & AGM84?

[nidrac]

Hey, Just a quick question, i'm reletively new to using GPS's and my unit uses the Datum WGS 84 but the chart i have uses AGM84. Just like to know what the difference is if any and how to convert them over

Cheers

[Kerry]

There is a difference between WGS84 and AGD84 (AMG84 is UTM coords in AGD) and this varies depending on the location from about 170 metres to roughly 230 metres across the country.

Based on Lucinda the difference is close enough to 211 metres (give or take an inch). The shift direction from AGD to WGS84 is "roughly" to the north-east. To match your chart from WGS84 to AGD then the shift is to the south-west for approx 211 metres. AGD Latitude will increase, longitude will decrease by fairly constant values over a reasonably large area.

If you insist on using what is probably an outdated chart then the GPS should be able to be configured to show lat/Long in AGD84 (the old chart datum).

Would suggest checking if new WGS84/GDA94 charts exist for the area and since the area is a shipping area then this was most likely down quite some time ago.

Regards, Kerry.

[nidrac]

That makes a whole lot more sense now thanks mate.