The Global Positioning System is a satellite navigation system which is developed by the USAF Space Division. This system provides highly accurate position and precise time for the user. The principle of this system is the interaction between the satellites, the receiver and the control station. The subject of this report is the processing of the raw data that are received from the satellites. In this research the Magnavox MX4200D GPS receiver is used. This GPS receiver has the multi-port as the output. One of the component of the multi-port is the raw data port. From this raw data port, the information to calculate the user or the receiver position can be obtained. This information is given in the form of the raw data which can be filtered and then used to calculate the user or the receiver position. The software to convert, filter and calculate the position are developed and described in this report. Using the software described in this report, the user has a possibility to get the data from the receiver into the file and it can also use this data for the calculate the user position coordinates.