??? Etrex Datum Setup ???

[+gpsjester]

Recently bought an Etrex (Yellow) and also purchased an OS Explorer Map (1:25 000).

 

I have set the Etrex up so that the coordinates are displayed as British Grid format i.e SD123456. But when I view a waypoint/coordinate etc. it only seems to display 5 figures i.e SD12345.

 

If I do a search using Streetmap.co.uk (using the 5 figure format) it comes back with an error, asking for another digit. So I thought, oh, you must have to stick a 0 on the end... but no, that gives me a totally different coordinate and of course, an incorrect location on the displayed map.

 

Could anybody explain why it is only displaying 5 figures and can I amend it to display 6.

 

Guidance much appreciated....

[+The Wobbly Club]

Hi Make sure that you have set the datum as British Grid and Ord svy. You should then get a position with 10 figures eg. SU12345 67890.

 

Hope this helps.

 

Colin

[+naffita]

Mine shows 10 figures, eg first line TF 57056, second line, BNG 60799.

I've never used BG but I think the figures you want would be TF 570607, that is , lose the last 2 numbers on each to use streetmap.

[NickPick]

in streetmap, you need to put in the co-ords in x,y format. It's expecting a 12 fig grid reference, ie metres from datum. The Etrex gives a 10fig GR, and the two letters tell you what 100km grid square you're in.

 

to convert naffita's exaple, you need to know that TF is the square that's 500km east, 300km north. so add a 5 to the front of 57056, and a 3 to the front of 60799. this gives you 557056,360799, which streetmap puts on a headland just south of Skegness.

 

I've got a little bitmap of the grids, which I can email you if you want a copy.

 

Nick

[+gpsjester]

ORD Svy...... How did I not see that in the list !!!

 

Thanks Wobbly Club

 

These Forums are worth their weight.....

 

Thanks Again.

[+John & Hazel]

ORD Svy...... How did I not see that in the list !!! 

 

Thanks Wobbly Club

 

These Forums are worth their weight.....

 

Thanks Again.   

Don't forget to change it back to WGS84 / DD. MM.mmm when you use the co-ords from GC.com

[+Pharisee]

Mine shows 10 figures, eg first line TF 57056, second line, BNG 60799.

I've never used BG but I think the figures you want would be TF 570607, that is , lose the last 2 numbers on each to use streetmap.

When I first used my Etrex Legend with OS references I thought that the display was showing the grid reference on the top line and the digits after the BNG were some sort or bearing reference and I couldn't get anything to work either.... ho hum

Then it was pointed out to me that the BNG stood for British National Grid and that the the five digits that followed it were the second half of the grid reference.

 

Yes... I did feel a bit of a fool but I suspect I'm not the only one who's made that sort of mistake.

[+Nellies Knackers]

You're not wrong Pharisee!

[Mittellegi]

To get the GPS to display a 12 figure OS grid reference, you can set the Position Format to "User UTM Grid", with the following parameters:

 

Longitude Origin: W 002° 00.000'

Scale: +0.9996013

False Easting: +400000.0

False Northing: -5527064.0

 

And as previously mentioned, don't forget to change the Map Datum to "Ord Srvy GB"

[+jhob]

So for geocaching on my etrex legend I should use the 'WGS84' datum and 'hddd mm.mmm' position format, but for map reading the datum should be 'Ord Srvy GB' with position format 'British Grid'?

 

Got a bit confused yesterday on my first proper day geocaching with getting it all set up correctly!

[+leecee]

So for geocaching on my etrex legend I should use the 'WGS84' datum and 'hddd mm.mmm' position format, but for map reading the datum should be 'Ord Srvy GB' with position format 'British Grid'?

Correct.

[+John & Hazel]

So for geocaching on my etrex legend I should use the 'WGS84' datum and 'hddd mm.mmm' position format, but for map reading the datum should be 'Ord Srvy GB' with position format 'British Grid'?

 

Got a bit confused yesterday on my first proper day geocaching with getting it all set up correctly!

If you are entering co-ords from GC.com they should be in WGS84/ DDD MM.mmm

and your legend should be set up accordingly.

If you are entering co-ords in OS/ British Grid your legend should be set up to that format.

Provided you have done that correctly, you can navigate with the GPSr set to either. The positions are the

same (to within an acceptable accuracy)

Just double check Datum and position format before entering any numbers.