GPS for Dummies

I have a Garmin handheld GPS and want to figure out how to understand the Lat/Lon information.

In my area the main readings are the 33 XX & 118 XX, I'm trying to figure out what the 33 or 118 represent. Are they miles, if so what is the XX and the XXX represent?

Somebody told me all I need to put in the GPS to find a location is the 33 & the 118 XX and not the last three XXX, are the last three digits just feet?


This posting may have been duplicated, the site timed-out early and I'm not sure if it went through.

Thanks for your help.


Clueless with GPS in Hand.

Re: GPS for Dummies

I suggest you visit the library and take a long hard look at a globe. You will see a series of lines going from the north pole to the south pole and then continue on around the other side back to the north pole again. Those are lines of "longitute" which are expressed in degrees and minutes. You will also note there are horizontal lines that circle the globe. Those are lines of latitude and are also expressed in degrees and minutes. Latitude is expressed either north or south of the equator. Longitude is expressed either east or west. So the numbers you enter into the GPS are latitude and longitude which pinpoints you location on the globe.

Re: GPS for Dummies

Thanks Silvertip,

I'm starting to understand & I will visit the Library to follow up, I'm a little puzzled still on the last three digits of the GPS setting.

When I listen to boaters call in for assistance to find a location the responder only seems to give part of the Lat/Lon, for instance they may say something like 33-35 and 118 -30. They leave out the last three digits that the GPS is looking for, I assume this limited Lat/Lon should get me close to the location and the last three digits must respresent how many feet between say 118-30 and 118-31.

If so I think I have this figured out, the last three digits can only 999 at its larger gap. Is the 999 feet?

I know the Lat/Lon as you decribed is referrenced in minutes, but I'm assuming these minutes also must have a distance value. If I can make this connection then I'm on my way to truely understanding how this works.

Thanks/Jerry

Re: GPS for Dummies

Go here to learn how the latitude/longitude system works. The three numbers represent "degrees", "minutes" and "seconds" which are explained in the article.

http://en.wikipedia.org/wiki/Latitude_and_longitude#Degrees:_a_measurement_of_angle

There obviously is a distance relationship but when using map coordinates that value is meaningless because it varies depending where you are on the globe. Look at the distance between two longitude lines on a globe at the equator. Then look at the same two longitude lines near the poles. You'll notice they are much closer together at the poles than the equator.

Re: GPS for Dummies

Silvertip,

Excellent information, the link was great and I'll still follow up with a class or the library. This is tricky stuff, but I know more now then I did yesterday.

Thanks for the help.

Jerry

Re: GPS for Dummies

Glad you didn't get a Loran unit !

Re: GPS for Dummies

The default for most GPS settings is degrees, minutes.thousandths of a minute. 38 18.324 N latitude by 123 03.005 W longitude.
The 38 is degrees 18 is minutes and .324 is thousandths of a minute.

Many times people will just give the degrees and minutes, as if you get that close on a clear day you will be able to see the other boat.

Most units can also be set to degrees 38.14952 degrees.

Also most units can be set to Degrees 38. minutes 18, seconds 40.9