GPS Flashcards
GPS
Global Positioning System
what is the GPS a part of
GPS is part of the Global Navigation Satellite System (GNSS) operated by the USA
what does the gps consists of and how is it designed
MINIMUM 24 satellites (with some spares). it’s designed so at least 5 satellites are in view at any given location on earth
how far above are the satellites
orbit the earth at 10,900 NM
how does GPS receiver calculate distance
the aircraft’s GPS receiver calculates the distance to a GPS satellite based on the timelapse since the broadcast timestamp (obtained from an atomic clock onboard the satellite) and the time it received the signal
what is pseudo range
pseudo range is satellites distance range. it’s the overlapping of pseudo ranges of how the gps can calculate your geographic position
how are course and speed data computed
from aircraft position changes
how many satellites are required for position reporting
- 3 satellites for 2D position (longitude & latitude)
- 4 (at least) satellites for 3D positioning (altitude, longitude & latitude)
RAIM and what it does
Receiver Autonomous Integrity Monitoring
MONITORS the integrity of the satellite signals
RAIM fault detection
minimum of 5 satellites OR 4 satellites + 1 baro-aided
it just TELLS you their is something wrong with a satellite and its signal
RAIM fault exclusion
minimum of 6 satellites OR 5 satellites + 1 baro-aided
it GETS RID OF the corrupt satellite
airborne GPS units use
great-circle navigation
5 satellites in a line, are the satellites able to accurately calculate our exact position
no
what does the GPS CDI show
distance
what can a GPS substitute
ADF (Automatic Direction Finder) or DME
except for ADF substitution on NDB approaches without a GPS overlay ( or “GPS” in title
