A refined method for determining true ground speed has been developed which is particularly applicable to agricultural and off-highway equipment. The radar sensor provides a conditioned output signal whose frequency is directly proportional to true ground speed. Applications include precise vehicle speed display, transmission control, wheel slip control, and agricultural equipment control for planting, spraying, harvesting, etc. Advantages include increased farm productivity, maximized crop yield, reduced fuel consumption etc. The radar sensor can interface with on-board microprocessor based equipment for controlling farm implements with greater accuracy and at higher vehicle speeds than previously possible. The radar sensor described is readily adaptable to most tractors, easy to install and service, extremely rugged, and environmentally secure.