Doppler tracking for position determination 2

• Main Author: Chan, Yong Hong.
• Other Authors: Cheng Tee Hiang
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: http://hdl.handle.net/10356/47706
• Institution: Nanyang Technological University

Doppler Tracking allows the distance between a satellite transmitting from space and a radio receiver on the ground to be measured by analysing how the frequency received from the satellite changes as it approaches, passes overhead, and moves away from the receiver. The position vectors of the receiver can then be calculated since the satellite position, determined by ephemeris data tagged with time produced by the downlink radio signal transmitted from the satellite to the receiver, and Doppler measurements involving computing Doppler count from the analysed frequency are known. In the event that GPS is not available, Doppler Tracking and positioning can be used as a precise and inexpensive replacement to calculate the position of a receiver. This project focuses on simulating a receiver to determine its location using a low earth orbit (LEO) satellite. Geometrical analysis of the movement and orientation of the LEO satellite and measurements of Doppler count are required for the receiver to calculate its position. In this project, a LabView software prototype has been designed and implemented. It has algorithms to simulate real time velocity and position of a LEO satellite, measure Doppler Count and determine a receiver position. The velocity and position vectors of a satellite are first analysed to determine the period of time when there will be line of sight (LOS) between the satellite and the receiver. Subsequently, during this period, the receiver receives frequency emitted by the satellite every even minute. Hence, Doppler count can be measured. The receiver position is then computed based on a recurring algorithm.