Abstract: A low-cost, solid-state position sensor system suitable for making precise code and carrier phase measurements in the L1 and L2 bands of GPS uses an ordinary, low-cost OEM card single-frequency carrier phase tracking C/A code receiver and includes low-cost hardware for sensing the L1 and L2 components of GPS carrier phase. Such measurements are suitable for general use in a variety of fields, including surveying. They are also of sufficient quality to be used in controlling heavy machinery, such as aircraft, farm tractors, and construction and mining equipment. A C/A code continuous tracking GPS receiver is used to produce GPS positioning fixes and real-time L1 carrier phase measurements. This C/A code receiver generates timing and reference information for a digital sampling component. This sampling component processes the L1 and L2 signals from the GPS signals in view.