This article deals Global Navigation Satellite Systems (GNSS). A detailed description of the notes will be provided on the given syllabus.

Global Navigation Satellite Systems

UNIT-I

GPS fundamentals

GPS System Segments:

space
control and user segments
Principle of operation
Current status of GPS satellite constellation

Orbital Mechanics:

GPS ephemeris data
Algorithm for computation of satellite’s position from ephemeris data

Time References:

solar and sidereal days
UTC time
GPS time.

UNIT-II

GPS signals

Legacy GPS signals:

Signal structure
Operating frequencies
C/A and P-Code
Navigation message

Modernized GPS signals:

list of signals and their significance
Range measurements:
code and carrier measurements
User position estimation with PRN codes.

Coordinate systems:

Earth Centered Earth Fixed (ECEF) coordinate system,
Earth Centered Inertial (ECI) coordinate system
Geodetic coordinate system
Ellipsoid and Geoid
Regional and Global Datum
World Geodetic System (WGS-84).

UNIT-III

GPS error sources
Satellite clock error
ephemeris error
Receiver clock errors
satellite and receiver instrumental bias
Multipath error
receiver measurement noise
ionospheric error
tropospheric error
Klobuchar model
ionospheric delay estimation using dual frequency measurements and UERE
Dilution of precision: HDOP, VDOP, TDOP, PDOP & GDOP.

UNIT-IV

Data formats:

RINEX Observation and Navigation Data formats

GNSS:

architecture
operation and signals of other global satellite systems such as Galileo, Beidou,
GLONASS and regional systems such as IRNSS, QZSS.

UNIT-V

Differential GPS (DGPS):

Principle of DGPS
Types of DGPS:
Local Area DGPS (LADPS), Wide
Area DGPS (WADGPS).

GPS Augmentation systems:

Principle of operation of Satellite Based Augmentation system (SBAS)

Ground Based Augmentation System (GBAS):

GNSS Applications Surveying
Mapping
Marine, air and land Navigation,
Military and Space Application.

Unit 1 Notes:-

Introduction to GPS: CLICK HERE

Introduction: CLICK HERE

Fundamentals of GPS: CLICK HERE

Unit 2 Notes:-

GPS Signal_Part 1: CLICK HERE

Coordinate Systems Part 2: CLICK HERE

Unit 3 Notes:

GPS Errors: CLICK HERE

GNSS Errors: CLICK HERE

MID 1 PAPER

1. How does communication occur between the space, control, and user segments in the
GPS system?
2. Multiple satellites are used in the GPS constellation for accurate positioning. Elaborate
the significance with necessary illustrations.
3. Differentiate between solar and sidereal days and their relevance in GPS timekeeping.
4. Explain the algorithm used for the computation of a satellite's position from ephemeris
data.
5. Identify the operating frequencies used by legacy GPS signals.
6. Describe the process of triangulation using PRN codes to determine user positions.
7. How is the navigation message utilized by GPS receivers for navigation calculations?
8. Explain how the choice of ellipsoid affects GPS positioning accuracy.
9. Analyze the impact of tropospheric error on GPS signal propagation.
10. Propose recommendations for improving the robustness of GPS systems against errors.
11. Evaluate the importance of clock synchronization for both satellites and receivers in GPS.
12. Suggest methods to compensate for ionospheric error in GPS positioning.
13. What are the three main segments of the GPS system, and what role does each segment
play in the overall system?
14. Summarize the role of trilateration in determining the user's position in GPS.
15. Explain the principle of operation behind GPS and how it enables accurate positioning.
16. List the components of GPS ephemeris data and explain their significance in satellite
positioning.
17. Discuss the significance of having multiple frequencies in the legacy GPS system.
18. Differentiate between the ellipsoid and geoid in the context of coordinate systems.
19. Explain the purpose of using both C/A and P-Code in the legacy GPS system.
20. Explain the basic structure of legacy GPS signals and the information they contain.
21. Compare and contrast tropospheric error with other error sources in GPS.
22. Create a flowchart illustrating the steps involved in minimizing errors in GPS positioning
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Mid 1 Answers: CLICK HERE

Global Navigation Satellite Systems || GR20 GNSS Notes