1.2
System Requirements
System requirements for using Expert GPS CLOCK are as follows:
•
a PC running under Windows 95/98/ME/2000/NT/XP
•
a free serial port (SUB-D, 9 pin) and/or one USB port
•
unobstracted view to the sky (e.g. through a window)
•
at least 3 MB hard disk space, 2 MB free RAM
1.3
Information about GPS
The Global Positioning Sytem (GPS) is a system for worldwide
navigation and determination of positions developed by U.S.
Department of Defense (DoD). It consists of 24 satellites travelling
around the earth on six orbits at a height of about 20,200 km. Each
satellite needs twelve hours for an earth surrounding. Because of the
alignment of the GPS satellites at least five satellites should be
visible at all time assuming an unobstructed view to the sky.
Each satellite continuously sends a signal at a carrier frequency of
1575.42 Mhz. A low frequent wanted signal is modulated onto the
carrier frequency delivering the satellite's position data (orbit) as
well as precise time information from the satellite's atomic clock.
With a simultaneous reception of three satellites a GPS receiver is
able to derive exact position data (longitude and latitude) from the
differential
delay of the satellites' signals. A fourth satellite is
necessary to get the altitude information.
In addition to the location and navigation information, exact time
information (UTC) is provided.
Expert GPS CLOCK
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