Telit Wireless Solutions SL869T3-I, Руководство пользователя

Страница: 63 / 68

SL869T3-I Product User Guide
1VV0301546 Rev. 3
Page 63 of 68 2021-03-31
18. GLOSSARY
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) The Chinese GNSS, currently being expanded towards full operational
capability. Formerly called COMPASS.
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).
GDOP
Geometric Dilution of Precision
A factor used to describe the effect of satellite geometry on the accuracy
of the time and position solution of a GNSS receiver. A lower value of
GDOP indicates a smaller error in the solution. Related factors include
PDOP, HDOP, VDOP and TDOP.
GLONASS
ГЛОбальная НАвигационная Спутниковая Система
GLObal'naya NAvigatsionnaya Sputnikovaya Sistema