Relative Targeting with Differential GPS and Associated Error Mechanisms

In conventional differential GPS (DGPS), a GPS receiver's navigation solution is improved by removing errors that are common with those of a reference receiver of known location. DGPS is useful in relative targeting, where the goal is to guide a vehicle accurately to a target. Two types of differential corrections are considered: one is implemented in the measurement domain and the other in the navigation solution domain. Analysis shows that if pseudorange measurement biases dominate the problem, it is better to send pseudorange corrections, whereas if reference receiver survey errors dominate the problem, it is better to send corrections to the navigation solution. In either case, the difference between the resulting corrections is shown to be relatively small.