NAVSTAR/GPS/GLONASS Flashcards
5 Types of Signals
GPS(CA)/Commercial/Safety of life/Public regulated (Mil or P)/ Distress/
Galileo satellite number and configuration
30 Satellites/ 9 Spare/ 3 Planes / 23222 Km Oribit
Galileo Orbit Time
14 Hours
Galileo Frequency Bands
1164 - 1215 MHZ
1559 - 1591 MHZ
All in view
Tracking all satellites can instantly replace a lost signal with anothe being monitored
Search the Sky
After turning on GPS searches for stored data
NAVSTAR number of SATELITES
24 +1 (groups of 6)
NAVSTAR Orbit Height
20200km
NAVSTAR Coverage/config
6 Circular Planes 28DEG view of earthe
Define Mask Angle
Lowest angle above horizon that satellite can be used
Glonass: height
19100KM
Glonass Inclination
64.8DEG
Glonass Freq
L1 - 1.6 ghz
L2 - 1.2GHZ
What is the PRN code used for
PRN is a code used for the identification of the satellites and the measurement of the time taken by the signal to reach the receiver
Frequncy band for L1 and L2
UHF
What is corrected by the transmission of the signals on two frequencies (L1 and L2)
Ionospheric propagation error can be minimized by comparison of the L1 and L2 frequencies
What is Almanac Data?
Determines? `
Almanac data contains the position and geometry of all satellites. The receiver can determine:
Satellites functioning normally \
The PRN codes
Predicted positions
Takes 12,5 Minutes to download
Ephemeris Data
Needs to be downloaded from EACH satellite (12 Seconds to download)))
NEED A FLASH CARD FOR PRN
Orbital heights
GLONASS orbits occur at 19 000 km above the WGS 84 ellipsoid whilst NAVSTAR/GPS orbits occur at 20 200km
Orbital heights GLONASS + NAVSTAR
GLONASS orbits occur at 19 000 km above the WGS 84 ellipsoid whilst NAVSTAR/GPS orbits occur at 20 200km
Which of the following geometric satellite constellations provides the most accurate NAVSTAR/GPS position fix?
4 satellites with an azimuth of 90° from each other and an elevation of 45° above the horizon
Which of the following geometric satellite constellations provides the most accurate NAVSTAR/GPS position fix?
The most accurate GPS position fix is available from 4 satellites. 3 satellites with a 120 deg azimuth between satellites with the fourth satellite overhead the fix.
