Specifications

Cinterion
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ALAS66A Hardware Interface Overview
3 GNSS Interface
33
 ALAS66A_HIO_v01.000a 2019-02-26
Confidential / Released
Page 33 of 51
3 GNSS Interface
ALAS66A integrates a GNSS receiver that offers the full performance of GPS/GLONASS tech-
nology. The GNSS receiver is able to continuously track all satellites in view, thus providing ac-
curate satellite position data.
The integrated GNSS 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 GNSS 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 ephemeris data and
the precise time.
By default, the GNSS receiver is switched off. It has to be switched on and configured.
Dead Reckoning Sync Line:
Dead reckoning solutions are used in (automotive) platforms to determine the (vehicles) loca-
tion even when there is no GNSS signal available (e.g. in tunnels, basement garages or even
between high buildings in cities).
In addition to dead reckoning related NMEA sentences, ALAS66A provides a dead reckoning
synchronization line (DR_SYNC line) to be employed in external dead reckoning applications.
DR_SYNC is derived from the GNSS signal clock as 1 pulse per second (1PPS) signal. The
DR_SYNC signal is provided as long as synchronized with the GNSS satellite clock, and con-
tinues after GNSS signal loss.