Date Added: May 2012
Now-a-days, Global Positioning Satellite system (GPS) is playing a major role in military and navigation applications. In general, GPS is mainly used for the position determination when there is a presence of the signal. However, problem occurs during the absence of signal or very low signal, which may be caused by various geophysical and technical aspects. For instance, first order errors like tropospheric and ionospheric errors and second order errors like multipath and interference that may provide unexpected errors to the radio wave signal that is being radiated from one of GPS satellites.