Cobra Electronics GPS 500 - Manual (Page 31)

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G E N E R A L I N F O R M AT I O N
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G E N E R A L I N F O R M AT I O N
World City Time Zones
Longitudinal Zone Offset
E172.50 to W172.50 ..............................-12
IDLW (International Date Line West)
W172.50 to W157.50 ............................-11
Nome
W157.50 to W142.50 ............................-10
Honolulu
W142.50 to W127.50 ..............................-9
Yukon Standard
W127.50 to W112.50 ..............................-8
Los Angeles
W112.50 to W097.50 ..............................-7
Denver
W097.50 to W082.50 ..............................-6
Chicago
W082.50 to W067.50 ..............................-5
New York
W067.50 to W052.50 ..............................-4
Caracas
W052.50 to W037.50 ..............................-3
Rio de Janeiro
W037.50 to W022.50 ..............................-2
Fernando de Noronha
W022.50 to W007.50 ..............................-1
Azores Island
W007.50 to E007.50........................GMT + 0
London
E007.50 to E022.50 ................................+1
Rome
E022.50 to E037.50 ................................+2
Cairo
E037.50 to E052.50 ................................+3
Moscow
E052.50 to E067.50 ................................+4
Abu Dhabi
E067.50 to E082.50 ................................+5
Maldives
E082.50 to E097.50 ................................+6
Dhuburi
E097.50 to E112.50 ................................+7
Bangkok
E112.50 to E127.50 ................................+8
Hong Kong
E127.50 to E142.50 ................................+9
Tokyo
E142.50 to E157.50 ..............................+10
Sydney
E157.50 to E172.50 ..............................+11
Solomon Islands
E172.50 to W172.50 ............................+12
Auckland
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Sources of Interference / Errors:
GPS receivers have the potential for position errors due to
interference, primarily from the following sources:
Ionosphere and troposphere delays
The satellite signal slows as it passes through the atmosphere.
The system uses a built-in model that calculates an average
– though not exact – amount of delay.
Signal multi-path
This occurs when the GPS signal is reflected off objects such
as tall buildings before it reaches the receiver. This increases
the travel time of the signal, causing errors.
Receiver clock errors
The built-in clock can have very slight timing errors.
Orbital errors
Also known as ephemeris errors, these are inaccuracies of the
satellite’s reported location.
Most common error
Most common error is not having a clear view of the sky, or
being under very cloudy conditions, when a satellite signal
may not be received.
Number of satellites visible
The more satellites the receiver can see, the better the
accuracy. Buildings, terrain, electronic interference or even
dense foliage can block signal reception, resulting in position
errors or possibly no position reading at all. In general, the
clearer the view of the sky is at your location, the better
the reception will be. GPS receivers will not work indoors,
underwater or underground.
Due to the errors that might occur, it is recommended that
the serious navigator use a second navigational tool, such as
a magnetic compass or map.
When satellite lock is lost
Whenever satellite lock is lost, the following animation
sequence appears onscreen and continues to loop until
satellite lock is re-acquired.
When GPS is turned Off
Whenever GPS is turned Off, the following animation
sequence occurs and continues to loop until search is
activated by user.
Also, all data fields (except for power status data
fields) appear blank until GPS is turned On and
satellite lock is re-acquired.