Aircraft speed measurement systems such as mechanical speed meters, inertial, Doppler systems, satellite systems are discussed in this article and factors influencing their accuracy are presented. For evaluation of vehicle‘s speed measurement errors by satellite system sensor the experiments were carried out using a car the speed of which was 60 km/h and kept constant on the flat road segment of 2.5 km in length. Speed measurement data as arrays of NMEA sentences was recorded and excerpts of arrays when the number of „visible“ satellites was from 6 to 11 were postprocessed. By adapting the curve fitting method the empirical exponential function model is proposed for the relationship between vehicle‘s speed errors and the number of „visible“ satellites. This model can be used for evaluation of speed errors of GNSS sensors.

Article in: Lithuanian

Article published: 2014-08-05