Method for passively measuring the speed of a vehicle

摘要

The speed of a vehicle is to be determined by evaluating the radiated wave energy without disclosing one's presence. Dispersion characteristics of the transmission medium in the measuring area are utilised for the measurement in that the interference field coupled to the vehicle of the natural waves propagating in the transmission medium is measured by two transducers arranged at a distance from one another. Received signals of the transducers are subjected to a frequency analysis and intensities are stored in dependence on measurement time and frequency. A section of such an intensity pattern within a predeterminable frequency range and time interval of received signals of one transducer is brought to coincidence with an equally large intensity pattern of received signals of the other transducer by displacement with respect to time. The time displacement between the intensity patterns is a measure of the vehicle speed. The use of this measuring method is particularly effective in underwater sound applications.