EndRun Sonoma N12, Руководство пользователя

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S o n o m a U s e r M a n u a l 136
A P P E N D I X E
137 S o n o m a 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
Record the position and then make any adjustments to the height that might be necessary if the
antenna is installed in a high-rise building. Input it to the Sonoma via the
setgpsrefpos
command.
(See Chapter 9 - Console Port Control and Status .)
Using “Indirect GPS”
There are some locations where using a GPS window-mount installation is not practical, either be-
cause of metallic films on the window, or the view from the window is blocked, or the window is fac-
ing away from the equator. In these cases we have an alternative product that uses CDMA cell phone
signals for time synchronization. We call it “indirect GPS”. CDMA is not available worldwide, but
if you work in an area with CDMA cell phone service then you will probably be able to mount your
antenna on top of your equipment rack inside your data center. Contact EndRun Sales or Support for
more information.
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 Sonoma, 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)