Satellite Navigation Systems

Question 1

What are the 4 main GNSS?

Answer 1

• USA NAVSTAR GPS
• Russian GLONASS
• European Galileo
• Chinese BeiDou

Question 2

What are the two modes of operation?

Answer 2

SPS - standard positioning system (civilian)

PPS - precise positioning system (military)

Question 3

What are the 3 segments comprised of GNSS?

Answer 3

Space, user and control

Question 4

What is in the navigation message transmitted by a satellite?

Answer 4

• satellite health status
• ionospheric model
• UTC parameters
• satellite clock correction parameters

Question 5

How many satellites are required to calculate a 3D position?

Answer 5

4

Question 6

How many satellites are required for RAIM?

Answer 6

5

Question 7

What are the factors affecting the size of user UERE?

Answer 7

• ionospheric propagation delay
• dilution of position
• satellite clock error
• satellite orbital variations
• multi path

Question 8

What’s the distance GBAS provides?

Answer 8

20nm

Question 9

What is the minimum coverage of GBAS?

Answer 9

10 degrees either side of the nominal centreline of an approach path out to 20nm and 35 degrees out to 15nm

Question 10

How quickly should SBAS alert users if GPS malfunctions?

Answer 10

6 seconds

Question 11

What SBAS is in use?

Answer 11

EGNOS: Western Europe

WAAS: USA

MSAS: Japan

GAGAN: India