EndRun Meridian II, User Manual

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M e r i d i a n I I U s e r M a n u a l 178
A P P E N D I X E
179 M e r i d i a n I I U s e r M a n u a l
I N S T A L L I N G T H E G P S A N T E N N A
Mounting On
A Rooftop
Mounting your GPS antenna with an unobstructed view of the sky (usually on a rooftop) is the
recommended installation. Please follow these guidelines to eliminate exposure to electrical service
wiring and to minimize the potential for lightning strikes.
Installations subject to lightning strikes should use a lightning arrestor installed at the building en-
trance. A lightning arrestor suited for this purpose is available through EndRun Technologies. The
arrestor must be installed according to the manufacturer’s instructions.
Do NOT route the antenna wiring near or with AC wiring (Class 1 circuits per the NEC). Do NOT
mount the antenna wiring where it may become energized by nearby AC wiring or components
should they fall.
Obtaining A
Reference Position
Your Meridian II is capable of operation from either an automatically determined GPS reference
position or a manually entered GPS reference position. If you need to provide a reference position
to your Meridian II, it is best to use a previously determined position from the unit itself or a highly
accurate surveyed position.
About WGS-84
Height
Internally, GPS receivers report latitude, longitude and height above the WGS-84 ellipsoid. Howev-
er, for a lot of reasons, WGS-84 is not the way that mapmakers and surveyers report the height. That
means, in order to use the height information as reported by Meridian II, you need to do a conversion.
One easy way to do the conversion is by going to this link:
http://www.unavco.org/community_science/science-support/geoid/geoid.html
After entering your latitude and longitude, this website will give you a report showing the GPS ellip-
soidal height, the Geoid height, and the Orthometric height. The Orthometric height is the one most
people are familiar with, which is height above mean sea level. However, GPS receivers use the GPS
ellipsoidal height. Below is a sample report:
GPS ellipsoidal height = 0 (meters)
Geoid height = -31.023 (meters)
Orthometric height (height above mean sea level) = 31.023 (meters)