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| NAD-83 |
See North
American Datum of 1983 |
| Nanosecond |
One billionth of a second. |
| NAS |
National Airspace System |
| NAVDATA |
The 1500 bit navigation message (NAV message) broadcast by
each satellite at 50 bps on both L1 or L2 frequencies. This
message contains system time, clock correction parameters, ionospheric
delay model parameters, the satellite's ephemeris and it's health.
This information is used to process GPS signals to obtain user
position and velocity. It is also used when processing precise
surveying data. |
| Navigation Interval |
The rate at which the receiver samples and stores the NAV
message. |
| NAVSTAR |
NAVSTAR is a constellation of 24 satellites, launched by
the American Department of Defence. They are the satellites
used by most GPS receivers to calculate your position. |
| NDB |
Non-directional Beacon |
| NMEA 0183 v2 |
The US national standard for navigational related information,
which FieldWorker uses to receive GPS information from GPS receivers.
Any receiver which transmits in this protocol can be utilised
by FieldWorker. |
| North American
Datum of 1927 (NAD-27) |
Older and obsolete horzontal datum of North America. NAD
27 depends upon an early approximation of the shape of the earth,
known as the clarke Spheriod of 1866, designed to fit only the
shape of the conterminous United States, and utilizing a specific
Earth surface coordinate pair as its center of reference. |
| North American
Datum of 1983 (NAD-83) |
Official horizontal datum of North America. NAD 83 relies
on the more precise Geodetic Reference System of 1980 (GRS 80). |
| North American
Vertical Datum of 1988 (NAVD-88) |
Effort underway by the National Geodetic Survey (NGS) to
readjust the North American Vertical Datum. The NAVD 88 readjustment
will remove distortions from the continent-wide vertical geodetic
(height) reference system. |
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