Perpustakaan Digital ITB

Global Positioning System (GPS) receiver is navigation equipment that can determine position, velocity and time by utilizing signal transmitted continuously by GPS satellites. It has been used widely in much area such as aviation, maritime, geodesy and others. However most of GPS receivers have accuracy about 15 meters that is not accurate enough for some works that need precise data location like Category I, II and III precision approach. This research project will develop a simple and low cost system that can improve the accuracy of GPS receiver using DGPS basic principle. The system is consisting of at least two stations; one fix reference station and one moving station. Each station consists of a laptop, a GPS receiver and a stand alone modem. The fix reference station will measure the difference between the positions indicated by the satellite systems and the known fixed positions, then broadcast it through modem. The moving receiver station receives the data, correct their position by the same amount and display the new position on laptop 2. The testing of the system has been done for several conditions such as different distance, weather and time. Result of the testing shows that the low cost DGPS system built comply the DR&O in general. It also gives better accuracy at cloudy night, bad and good weather condition however fairly accurate during day. Some faulty result obtained is because of the unreliable assumption made. However, overall average accuracy obtained is 7.2 meter for latitude and 5.1 meters for longitude which is less than 15 meters. iii