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Different Coordinates


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I have a Magellan Meridian Gold; the original setup was for western MA. I took the unit with me to KS to geocache some locations while visiting. The problem I encountered was that the coordinates listed for the caches did not match the readings on my GPS and I was in a different location and needed to search to find actual cache.

 

Why are my coordinates reading differently?

 

Thanks for the help,

 

mnthigh

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The usual culprit in these situations is that your datum has been accidentally changed from WGS84 to something else. For example, if your datum is set to NAD27, the GPS will be 100 to 300 feet off (or more) depending upon where in the US you are. Check your datum and see if it is set to something other than WGS84.

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Another likely suspect is Position Format error:

 

There are three different ways to express Latitude and Longitude coordinates, and their differences are very subtle. It's easy for a beginner to mistake one for another and enter the proper numbers into the wrong format - thus entering the wrong co-ordinates. Many have made this mistake in the past.

 

1) There's decimal degrees which is expressed as hddd.ddddd°

The "h" represents which hemisphere, and all of the numbers represent the whole and the remainder in degrees.

 

Example - The Washington Monument:

N38.88978° W77.03622°

 

2) There's degrees and minutes which is expressed as hddd° mm.mmm'

This is the format Geocaching uses. The whole number degrees, with the remainder expressed in decimal minutes.

 

Example - The Washington Monument:

N38° 53.387' W77° 02.173'

 

3) There's degrees minutes and seconds which is expressed as hddd° mm' ss.s"

The degrees are whole numbers and so are the minutes. The remainder is broken up into decimal seconds.

 

Example - The Washington Monument:

N38° 53' 23.2" W77° 02' 10.4"

 

It's important to have the correct numbers in the correct format. If I take the numbers from degrees minutes and seconds and put them into decimal degrees format, the difference is 24 miles to the south!

 

N38° 53' 23.2" W77° 02' 10.4" = Washington Monument

N38° 53.232' W77° 02.104' = 1,056 feet SE of Washington Monument

N38.53232° W77.02104° = La Plata, Maryland

 

GEOCACHING USES DEGREES AND MINUTES (#2 ABOVE)

 

The differences can be very small to very large (depending on what specific numbers are used and which format is used improperly. Be sure that YOU, your GPSr and software are all on the same sheet of music. There are preference settings for the GPSr and software.

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Another likely suspect is Position Format error:

 

There are three different ways to express Latitude and Longitude coordinates, and their differences are very subtle. It's easy for a beginner to mistake one for another and enter the proper numbers into the wrong format - thus entering the wrong co-ordinates. Many have made this mistake in the past.

 

1) There's decimal degrees which is expressed as hddd.ddddd°

The "h" represents which hemisphere, and all of the numbers represent the whole and the remainder in degrees.

 

Example - The Washington Monument:

N38.88978° W77.03622°

 

2) There's degrees and minutes which is expressed as hddd° mm.mmm'

This is the format Geocaching uses. The whole number degrees, with the remainder expressed in decimal minutes.

 

Example - The Washington Monument:

N38° 53.387' W77° 02.173'

 

3) There's degrees minutes and seconds which is expressed as hddd° mm' ss.s"

The degrees are whole numbers and so are the minutes. The remainder is broken up into decimal seconds.

 

Example - The Washington Monument:

N38° 53' 23.2" W77° 02' 10.4"

 

It's important to have the correct numbers in the correct format. If I take the numbers from degrees minutes and seconds and put them into decimal degrees format, the difference is 24 miles to the south!

 

N38° 53' 23.2" W77° 02' 10.4" = Washington Monument

N38° 53.232' W77° 02.104' = 1,056 feet SE of Washington Monument

N38.53232° W77.02104° = La Plata, Maryland

 

GEOCACHING USES DEGREES AND MINUTES (#2 ABOVE)

 

The differences can be very small to very large (depending on what specific numbers are used and which format is used improperly. Be sure that YOU, your GPSr and software are all on the same sheet of music. There are preference settings for the GPSr and software.

Thanks for the info, however I did check the input to make sure the format matched the Latitude and Longitude coordinates,

 

Mtnhigh

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The usual culprit in these situations is that your datum has been accidentally changed from WGS84 to something else. For example, if your datum is set to NAD27, the GPS will be 100 to 300 feet off (or more) depending upon where in the US you are. Check your datum and see if it is set to something other than WGS84.

The datum change could be the culprit. I was checking several setup items to solve the problem and I might have changed this setting by accident.

 

Thanks

 

Mtnhigh

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