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
what should you check when using GPS
GPS NOTAMS before the flight and use RAIM prediction
GPS Augmentation systems or Differential GPS (DGPS)
IMPROVES ye accuracy of the GPS by measuring errors received by reference stations known at geographical locations and then broadcasting those trios to supported GPS re
what are the two types of GPS Augmentation systems or Differential GPS (DGPS)
Satellite Based Augmentation System (SBAS)
Ground Based Augmentation System (GBAS)
what specifically about SBAS and what goes under it
Satellite Based Augmentation System is JUST an overall name
under comes individual things like WAAS: USA & EGNOS: Europe
WAAS
Wide Area Augmentation System
what does WAAS do and how does it work
it uses ground stations (Wide-area Reference Stations & Wide-area Master stations) measure GPS errors & produce correction signals
these correction signals are broadcasted back to the satellite segment from which the pay are bounced back to all aircraft GPS WAAS receivers
**IMPROVES accuracy, integrity & availability monitoring for GPS navigation
what does WAAS cover
covers a WIDE area
opposed to GBAS which is local
what does WAAS facilitate
facilitates APV (Approach with Vertical guidance) approaches such as:
LPV (Localizer Precision with Vertical guidance)
LNAV/VNAV (Lateral & Vertical Navigation)
non prescion approaches
GBAS
Ground Based Augmentation System
how does GBAS work and what does it allow
- errors are broadcasted VIA VHF to GBAS-enabled receivers
- allows for CAT l and above approaches to GLS (GBAS Landing System) DA minima
what is the difference between WAAS and GBAS
GBAS is MORE accurate then WAAS
BUT covers a MUCH SMALLER geographical area
what’s the difference between RAIM and WAAS
RAIM MONITORS integrity
WAAS IMPROVES integrity
