In DGPS, spatially correlated errors are easily eliminated by difference operations. However, the quality of code measurements is still not satisfactory compared to that of carrier phase measurements. The carrier smoothing technique is used in high-end receivers to generate carrier smoothed code measurement. With carrier smoothed code measurement, the accuracy of DGPS can be more increased, but high end receiver is still high cost and usually not provides raw measurements. In this paper, a Matlab based real time DGPS system which supports GPS, SBAS and GBAS using code and carrier smoothed code measurements is given. The implemented system is evaluated with real GPS measurements from the commercial receiver by serial communications. The accuracy and maximum output rate of Matlab based DGPS system on a PC will show the performance of the system.

Keywords: GPS, DGPS, SBAS, GBAS, Matlab.