High accuracy precise point positioning using a single frequency GPS receiver

Abstract

One of the dominant error sources for single frequency GPS users is the ionosphere. The magnitude of this error can vary from a few meters to hundreds of meters, especially during severe ionospheric disturbance periods. For undifferenced processing using a single frequency single receiver unit, the ionospheric error cannot be cancelled out using a differential process. Therefore, one needs to rely on using appropriate models or algorithms to correct this delay to achieve high accuracy point positioning. This paper reports on a study undertaken to evaluate two different ionospheric error mitigation methods for single frequency Precise Point Positioning (PPP) processing. The two methods studied were ionospheric modeling and ionosphere-free combination. The feasibility of using either of these methods was assessed using four processing options: code-only processing; code and carrier phase combination; single frequency ionosphere-free linear combination employing an additive combination of code and carrier phase measurements, which was abbreviated as the quasi-phase measurements; and the code and quasi-phase combination