en 5-Signal Processing Signal Processing Research Paper Research Paper <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">In determining position using GPS, due to local effects, pseudo-range errors cannot be mitigated by methods such as the use of reference stations or mathematical models; however, by using precise carrier phase observations and deploying a statistically optimal filter such as Phase-Adjusted Pseudo-range (PAPR) algorithm, the error can be significantly reduced. Additionally, the correlation between observations is a factor affecting positioning accuracy. In this paper, by using both pseudo-range and carrier phase observations and taking into account the effect of spatial correlation between observations to determine the variance-covariance matrix, the accuracy of position determination using the recursive Least Squares method is increased. For this purpose, the PAPR algorithm was implemented to reduce error. Next, a non-diagonal variance-covariance matrix was introduced to estimate the variance of the observations based on their spatial correlations. Experimental results on real data show that the proposed method improves positioning accuracy by at least 10% compared to previous methods. To evaluate the complexity of the proposed models, we employed an ARM STM32H743 processor. The findings indicate a modest increase in the proposed model complexity compared to earlier models, along with a substantial improvement in positioning accuracy.</span></span> GPS, Phase-Adjusted Pseudo-range Algorithm, Recursive Least Squares, Spatial Correlations, Variance-Covariance Matrix. 137 146 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-78-35&slc_lang=en&sid=1 Nerjes Rahemi Rahemi@iust.ac.ir 1800319475328460017244 1800319475328460017244 No The authors are with the School of Electrical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114, Iran. Kurosh Zarrinnegar k_zarrinnegar@elec.iust.ac.ir 1800319475328460017245 1800319475328460017245 No The authors are with the School of Electrical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114, Iran. Mohammad Reza Mosavi M_Mosavi@iust.ac.ir 1800319475328460017246 1800319475328460017246 Yes The authors are with the School of Electrical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114, Iran.