Understanding Datum’s

[+aliandtone]

Sorry if this has been asked before I have searched the forums but can’t find the answer.

 

When using my Garmin legend set to wgs84 and up load these coordinates

N50 °04.119 W000°31.506 to memory map they appear to be in the right place but memory map show the as 30N 669630E 5771563N it should also be set to wgs84.

 

Also on some maps they show N52°555 W000°555 e.g. can anyone explain if these have been rounded up or something else.

 

Many thanks

 

Aliandtone

[CenTexDodger]

Just to clarify WGS 84 is a map datum. It is a representation of how the world is drawan on a map. Location format is unrelated to datum. It can be lat/lon or some grid system such as MGRS. Lat/lon can even be expressed differently--

H dd mm'ss.s", H dd mm.mmm' or H dd.ddddd.

[+Sputnik 57]

Taking a quick look at your numbers, W000°31.506 is degrees mintutes and decimal minutes. W000°555 (or I'm betting W000.555°) is about the same point expressed as degrees and decimal degrees (31.5 minutes being about .525 degrees). I don't think that its a datum issue

 

I cant explain the lat goting from 50 to 30 to 52

[+Cornix]

.. memory map show the as 30N 669630E 5771563N it should also be set to wgs84.

That's UTM format (WGS84 datum), see this conversion.

 

It translates back to Lat/Lon (WGS84 datum) N 52°4.118 / W 0°31.507 (rounded) which looks OK.

 

Cornix

Edited June 24, 2005 by Cornix

[+blindleader]

"N50 °04.119". Is that a typo? Did you mean 52°04.119'?

 

You have your unit set up to display coordinates in UTM format and the 30N 669... is corrrect. FYI It doesn't matter what datum or display mode the receivers is set up in when you download waypoints. WGS84 and decimal degrees is the standard for waypoint transfer.

 

Some Legend owner will have to help on the other question.

[+Cornix]

"N50 °04.119". Is that a typo? Did you mean 52°04.119'?

Their profile says Stewartby/Bedfordshire (UK), so N52° should be correct.

 

Cornix

[+aliandtone]

"N50 °04.119". Is that a typo? Did you mean 52°04.119'?

 

You have your unit set up to display coordinates in UTM format and the 30N 669... is corrrect. FYI It doesn't matter what datum or display mode the receivers is set up in when you download waypoints. WGS84 and decimal degrees is the standard for waypoint transfer.

 

Some Legend owner will have to help on the other question.

Whoops yes typo

 

They should have read N52°04.119 W000°31.506

 

Sorry these (N52°555 W000°555) were just to show different decimal places and have no real meaning! Just wondered how to convert 5 digit to 7 digit references.

Edited June 24, 2005 by aliandtone