Hi Everyone,\n\nI am a Final Year Mechanical Engineering student from Nanyang Technological University in Singapore working on GPS related content with limited knowledge. As I am new to this forum please pardon me if I have made any mistakes with regards to posting and would also like to seek opinions on my queries.\n\nI am currently assessing the validity and reliability of a GPS (VXSport) device. I am trying to work with the raw data export which only provides speed and longitude/latitude (less altitude) data. VXSport has mentioned that the speed data that they obtained in independent of the longitude/latitude coordinates, mentioning that it is recorded directly from the GPS chip.\n\nOne of my tasks is to calculate speed using the longitude/latitude coordinates so that I can compare this value to that of the speed value recorded directly from the GPS chip. What I have done is that I have referred to this research paper specifically obtaining the section on user velocity [U][URL]http://d1.amobbs.com/bbs_upload782111/files_33/ourdev_584835O21W59.pdf[/URL][/U] but it seems that there is a lot more information required that I am unsure how I can obtain them, for example, XYZ coordinates of each satellite connected, frequency correction determined from navigation message updates. \n\nAside from branching to other topics such as Kalman filtering, I also understand that these iterative calculations may be done via computing programs instead of solving it in a mathematical. I would like to hear anyone's honest opinion regarding my project and especially if anyone could recommend me to any resources as to how GPS calculate speed using the longitude/latitude coordinates ideally with numerical examples. \n\nI deeply appreciate anyone who has taken time to go through my thread and sincerely apologize if I had stated any information incorrectly. Please feel free to let me know if there are any issues.\n\nThank You!