First, a brief description is given of an algorithm for the generation of carrier-adjusted differential corrections. Next, the relationship between satellite elevation and the precision of GPS code observations is investigated, on the basis of data collected by TurboRogue SNR-8000, Trimble 4000 SSE and Trimble 4000 SST receivers. It is concluded that the precision of code observations decreases with decreasing elevation, particularly at low elevation and that the relationship can quite well be modelled by an exponential function. For different types of receivers and different types of code observables, this relationship may not be the same.
