A low cost tracking system employing satellites of the global positioning system (GPS) is suitable for applications involving radiosondes, sonobuoys, and other objects. The tracking system includes a sensor mounted on each object which digitally samples the GPS satellite signals and records them in a data buffer. The digital samples are then transmitted, at a rate lower than that at which the GPS satellite signals were sampled, over a data telemetry link, interleaved with other telemetry data from the object. The GPS data is processed in a data processing workstation where the position and velocity of the sensor, at the time the data was sampled, is computed. The data buffer in the sensor is periodically refreshed, and the workstation periodically computes the new position and velocity of the sensor. Differential corrections are also provided at the workstation to aid in signal acquisition and to increase the precision of the position fix.