entering Lat/Long coordinates in a GPS

[Chip]

On my Garmin Etrex I can Edit a waypoint location to a destinations Lat/Long coordinates.
On the unit it currently reads N 41*27.508' W073*19.544'
I have to Edit that to a destinations location.
The coordinates I have are 42*09'44" by 74*04'50" OR 42.162206, -74.080228 (WGS84)
Is 42*09'44" by 74*04'50" the same as N 42*09.440' W 74*04.500' ?

 

[MichaelJ]

First of all, you have to be aware of the datum of your data so that the GPS and your data match. Those are discussed all over the place; I won't repeat them here.

Secondly, and I don't have my eTrex in front of me at the moment so this is from memory, there's a setting on it for units: UTM, DD.dddddd, DDMMSS, etc.

UTM is a special form. If you have locations beginning with "19T" which is the zone for much of the northeast, that's UTM. Otherwise it could be fractional degrees, degrees-minutes-seconds, etc.

And beyond that, it's easy. Just get into that waypoint screen, arrow to the coordinates, hit the enter button, and you can edit one digit at a time. It's not as pleasant as using a keyboard (understatement) but it works.

 

[MichaelJ]

As always, it's tough to tell without it in front of me to see exactly what the UI is showing, but I believe the answer is no.

73°19.544'
Degrees and fractional minutes

74°04'50"
Degrees, minutes, seconds

-74.080228
Fractional degrees

All are different. But if you go to the eTrex's units display setting, you should be able to set it to either of the latter two as well as the first where it apparently is now. Then it will display your current waypoint in that different form, and you can edit it with the corrected data in the same units.

 

[Chip]

thank you, that's what I needed to know.

 

[Neil]

Shameless thread hijack.

But at least the thread starter's question has been answered.

While on the topic, does lat-long depend on matching the datums in the same manner as UTM does? Furthermore, is one method superior to another? I read in "Make Your Own Maps" that some people consider UTM to be "Navigation for Dummies." UTM is all I've ever used.

 

[DougPaul]

MichaelJ is correct: one can set the format of the coodinates on the Garmin eTrex GPSes for both input and output. (IIRC, it uses one setting that covers both input and output.)

One method for converting between formats is to input in one format and change the format to read out the location in the second format. Laborious, but doable.

Doug

 

[DougPaul]

While on the topic, does lat-long depend on matching the datums in the same manner as UTM does? Furthermore, is one method superior to another? I read in "Make Your Own Maps" that some people consider UTM to be "Navigation for Dummies." UTM is all I've ever used.

Yes. All cordinate systems need a reference point and orientation (datum). (Where is 0,0 and which direction is grid north?).

UTM is a simplified coodinate system which treats the local area as a flat surface and has units of meters to make distances more intuitive. Useful only in small areas. IIRC, there is a special version of UTM for polar regions.

Lat-Lon treats the world as a sphereoid.

UTM is ok for local travel, but those who travel long distances (boats and aircraft) use Lat-Lon.

Doug

 

[jbreen]

If you don't have too many to convert, you can use this or this .

The program EasyGPS can convert a series of waypoints from decimal degrees to ddmmss and back. I don't know if it does others.

Jim

 

[Chip]

If you don't have too many to convert, you can use this or this .

The program EasyGPS can convert a series of waypoints from decimal degrees to ddmmss and back. I don't know if it does others.

Jim

WOW, Cool ! That's a keeper ! I could have used it yesterday, but...
Thanks.