SE868-V3 Product User Guide
1VV0301205 r4 – 2016-01-20
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 71 of 76
Mod. 0805 2015-02 Rev.4
17.
Glossary and Acronyms
AGPS:
Assisted (or Aided) GPS
AGPS provides ephemeris data to the receiver to allow faster
cold start
times than would be
possible using only broadcast data.
This extended ephemeris data could be either server-generated or locally-generated.
See
Local Ephemeris prediction data
and
Server-based Ephemeris prediction data
Almanac:
A reduced-precision set of orbital parameters for the entire GPS constellation that allows
calculation of approximate satellite positions and velocities. The almanac may be used by a
receiver to determine satellite visibility as an aid during acquisition of satellite signals. The
almanac is updated weekly by the Master Control Station. See
Ephemeris
.
BeiDou (BDS / formerly COMPASS):
The Chinese
GNSS
, currently being expanded towards full operational capability.
Cold Start:
A cold start occurs when a receiver begins operation with unknown position, time, and
ephemeris data, typically when it is powered up after a period on inactivity. Almanac
information may be used to identify previously visible satellites and their approximate positions.
See
Restart
.
Cold Start Acquisition Sensitivity
:
The lowest signal level at which a GNSS receiver is able to reliably acquire satellite signals and
calculate a navigation solution from a Cold Start. Cold start acquisition sensitivity is limited by
the data decoding threshold of the satellite messages.
EGNOS:
European Geostationary Navigation Overlay Service
The European
SBAS
system.
Ephemeris
(plural ephemerides):
A set of precise orbital parameters that is used by a GNSS receiver to calculate satellite position
and velocity. The satellite position is then used to calculate the navigation solution. Ephemeris
data is updated frequently (normally every 2 hours for GPS) to maintain the accuracy of the
position calculation. See
Almanac
.
ESD:
Electro-Static Discharge
Large, momentary, unwanted electrical currents that can cause damage to electronic equipment.
GAGAN:
The Indian
SBAS
system.
Galileo:
The European
GNSS
currently being built by the European Union (EU) and European Space
Agency (ESA).