lecture 7

Question 1

SBAS

Answer 1

satellite based augmentation systems
- a regional network of ground and satellite systems that work to boost the accuracy and dependability of GPS and GNSS data
-used for aviation, and also navigation

Question 2

how does SBAS work

Answer 2

• uses stationary land GNSS monitors
• monitors calculate GNSS position errors caused by atmospheric disturbances, satellite orbital error, and inaccurate clocks… each of these errors cause timing delays and therefore skew position calculation

Question 3

GNSS

Answer 3

global navigation satellite system
- a satellite constellation used for navigation and positioning information

Question 4

the main SBAS systems

Answer 4

WAAS: wide area augmentation system. US, Canada, Mexico: operated by US federal aviation administration
EGNOS EU: european geostationary navigation overlay service. developed by european space agency
MSAS : japan: multi-function satellite augmentation system, operated by japan civil aviation bureau
GAGAN: India, GPS aided GEO aumented navigation, developed by Space and Airport authorities of india

Question 5

WAAS and 4 components

Answer 5

• provides navigation services for national airspace system NAS
• provide augmentation info to GPS receivers to enhance accuracy
  components
  wide area reference stations
  wide are master stations
  GEO uplink systems
  GEO satellites

Question 6

wide area reference stations (WRS)

Answer 6

38
stations receive the GPS satellite signals
the locations of the stations are confirmed so any errors can be detected (like a GPS base station)

Question 7

wide area master stations (WMS)

Answer 7

3
reference sites send their data to these master stations
master stations generate a WAAS user message every second
messages tell GPS receivers how to remove errors in gps signal

Question 8

GEO uplink systems

Answer 8

6
master stations send messages to uplink stations for transmissions to satellites
sends to geostationary satellites

Question 9

GEO satellites

Answer 9

3
geostationary satellites
receive messages from the uplink systems
received into their navigation payloads
payloads broadcast the messages on a GPS like signal across the NAS

Question 10

typical accuracy of WAAS

Answer 10

0.63 meters horizontal, 1.0 meters vertical

Question 11

WAAS position accuracy standards

Answer 11

7.6 meters horizontal or vertical accuracy, at least 95 percent of the time

Question 12

differential correction in pathfinder office

Answer 12

• selecting your data files and base station
• setting parameters
• confirming and performing correction
• reading summary

Question 13

which correctional processing worked in final project

Answer 13

code corrected processing
zero carrier corrected positions