3.0 Results and Discussion
Reference Station Setup
The navigation signal from the GPS and GAGAN satellites are received by the ground receiver antenna and the navigation message from the antenna is passed to the GPS chipset. The Trimble Studio software receives the navigation message from the chipset in an NMEA 0183 format. The data collected from the software are analyzed to find the positional accuracy of GPS and GPS aided GAGAN with the know position of reference station.
3.1 Differential GPS Receiver Description
The GPS module has an automatic antenna switching function and short circuit protection. The GPS chipset is powered by the Media Tek Inc and it can support up to 66 channels. This receiver is enabled to receive the signal from the augmentation satellites, like WAAS, EGNOS, MSAS, and GAGAN.
3.2 Accuracy Analysis
For a good positioning accuracy, the receiver should get signal from four or more than four satellites. The analysis from figure 20 shows that there are six GPS satellites used for position fix so it is possible for the receiver to provide three Dimensional positioning. Moreover, if the availability of the satellites increases, then the positional accuracy will increase.
The GPS Aided and GEO Augmented Navigation (GAGAN) satellite with PRN number 127 and 128 was developed and operated by ISRO along with the Airport Authority of India. The GAGAN will help to increase the positional accuracy, availability, and integrity from the error porn GPS signal. The GAGAN corrects the ionospheric, ephemeris, and satellite clock errors from the GPS signal; the GAGAN with the GPS satellites will help to maintain a good positional accuracy than using the GPS alone for positioning.
The Geometrical Dilution of Precision (GDOP) also decides the positional accuracy. The Dilution of Precision (DOP) value should be within the limit in order to maintain a good positional accuracy. The analysis from the figure 21 shows that the GDOP is within the value 3 so that the confidence level for...