Artificial satellites are integrated with a wide area of applications expanding with a new contribution every day. The need for knowing the satellite''s state at a specific instant of time with variable accuracy requirements depending on the purpose exists for all artificial satellites. A variety of techniques has emerged since the first satellite launched to its orbit and more techniques will surely be involved as far as the pursuit of higher efficiency exists. There are various orbit determination strategies in which the GPS observables are involved. This book investigates different algorithms using the data from the GPS receiver on board the first Turkish remote sensing micro-satellite BilSAT-1. Pseudorange observations of BilSAT-1 obtained from TÜB¿TAK-UZAY are used to perform different orbit determination algorithms. Both a kinematic orbit determination approach with least squares estimation on the basis of Gauss- Markoff model and reduced-dynamic orbit determination approach with Kalman filter estimation algorithms are investigated to explore the affects of variations in the algorithms.