Velocity measuring system

Abstract

The relative transverse velocity between a local station and a zone of reference or observation is measured by providing first and second directional radiation receiving devices at the local station, such devices being aimed along parallel paths extending to the zone of reference. Such paths are spaced apart by a predetermined transverse distance. The first and second radiation receiving means include respective first and second converting means for converting the received radiation into first and second electrical signals. Any transversely moving radiation feature produces corresponding signal features in such first and second signals, such signal features being staggered with respect to time. The lapse of time between such staggered signal features is determined by time lapse measuring means. The velocity of such transverse movement is inversely proportional to such time lapse. The time lapse is preferably divided electronically into a constant which represents such transverse distance and a scale factor, to produce a quotient which is a direct measure of the velocity. The time lapse may be measured electronically with a high degree of accuracy. The received radiation may be either light focused by first and second optical systems, or radio waves received by first and second directional radio antennas connected to first and second radio receivers. The local station may be stationary, in which case the system may be employed to measure the velocity of objects or features in the zone of reference. Alternatively, the local station may be mounted on a movable vehicle, such as a helicopter, for example, in which case the system may be employed to measure the velocity of the vehicle relative to the zone of reference, which may be the terrain over which the helicopter is flying, for example. The velocity measuring system is adaptable to the measurement of the range and dimensions of objects in the zone of reference.