User's Manual

AHS3-W Hardware Interface Overview
4 GPS Receiver
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AHS3-W_HIO_v02.540a Page 28 of 41 2012-09-05
Confidential / Preliminary
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4 GPS Receiver
AHS3-W integrates a GPS receiver that offers the full performance of GPS technology. The
GPS receiver is able to continuously track all satellites in view, thus providing accurate satellite
position data.
The integrated GPS receiver supports the NMEA protocol via USB or ASC0 interface. NMEA
is a combined electrical and data specification for communication between various (marine)
electronic devices including GPS receivers. It has been defined and controlled by the US based
National Marine Electronics Association. For more information on the NMEA Standard please
refer to http://www.nmea.org.
Depending on the receiver’s knowledge of last position, current time and ephemeris data, the
receiver’s startup time (i.e., TTFF = Time-To-First-Fix) may vary: If the receiver has no knowl-
edge of its last position or time, a startup takes considerably longer than if the receiver has still
knowledge of its last position, time and almanac or has still access to valid ephimeris data and
the precise time.
By default, the GPS receiver is switched off. It has to be switched on and configured using AT
commands. For more information on how to control the GPS interface via the AT command
AT^SGPSC see [1].