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15.00 Glossary
15.00 Glossary
Active map
The map on a card which is in use (there
can be more than one map present).
Active route
Shown as a highlighted yellow line to follow
on the map.
Asc
Abbreviation for ascended height.
Atomic clock
A type of clock that uses microwave signals
emitted by electrons as its timekeeping
element. It is the most accurate time standard
and is used to control the frequency of GPS
satellite signals.
Bearing
Direction from one object to another.
CEP (Circular Error Probability)
Determines the radius of a circle containing
50% of the GPS readings.
Cross Track Error
The difference in distance between a planned
route and your location.
EGNOS
The European Geostationary Navigation
Overlay Service has been developed by the
European Space Agency (ESA) for safety of
air navigation. It is part of the Galileo project.
When a signal is available (which is only in
the south of England and mainland Europe),
this signal improves the accuracy of signals
from the GPS system.
Electronic compass
This doesn’t rely on GPS signals and works
whilst stationary. Whilst moving, the GPS
‘compass’ is more accurate.
Galileo
A planned global navigation satellite system,
being built by the European Union and
European Space Agency as an alternative for
the US Global Positioning System (GPS) and
the Russian GLONASS system. The project is
expected to be completed in 2013.
GLONASS
A radio-based satellite navigation system,
developed by the former Soviet Union and
now operated for the Russian government by
the Russian Space Forces. After completion,
the system fell into disrepair with the collapse
of the Russian economy. In 2001 Russia
committed to restoring the system with a goal
of full restoration by 2009.
GoTo point
A set point which acts as a target. It is on a
straight line from your current location and
the yellow highlighted route is a rough guide
only, eg. an emergency route off the hill in
worsening weather.
GMT (Greenwich Mean Time)
The local time at the 0 meridian passing
through Greenwich.
GPS
The Global Positioning System is the only fully
functional Global Navigation Satellite System
in the world. Created in the US it utilizes
a constellation of 24 Medium Earth Orbit
satellites that transmit precise signals. The
system enables a GPS receiver to determine
its time, location, speed and distance.
GPS ‘compass’
Whilst stationary the unit cannot determine
which direction you are facing. If you have a
GPS reading from two locations you can
determine the direction of travel.
Grid Magnetic Angle
The horizontal angular difference between
Grid North and Magnetic North. It is this angle
which needs to be applied when converting
between magnetic and grid bearings.
Grid North
The direction of a grid line which is parallel to
the central meridian on the national grid.
Heading
Direction you are travelling.
Hibernate mode
An ultra low power state giving signicantly
extended battery life and a rapid satellite
aquisition.
Inactive route
Shown as a grey highlighted line on the map.
Knot
One nautical mile per hour.
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