Vehicle protective apparatus

Claim 1

Vehicle safety apparatus comprising: directive oscillator-detector radio signal means adapted to be carried on said vehicle for directing frequency modulated transmissions toward an object and for receiving reflected signals therefrom, frequency discriminator means responsive to said oscillatordetector radio signal means for producing a first output signal having an alternating component whose amplitude is substantially proportional to the range between said vehicle and said object and having a unidirectional component whose amplitude is substantially proportional to the relative speed of said vehicle and said object, first series circuit means responsive to said unidirectional component for supplying a second output signal indicating the presence of said object only when reflected signals are received therefrom, said first series circuit means including: first comparator means responsive to said unidirectional component and to a first reference signal for supplying a third output signal only when said relative speed exceeds a predetermined value, demodulator means responsive to said first comparator means and to said oscillator-detector radio signal means, and second comparator means responsive to said demodulator means and to a second reference signal for generating said second output signal, second series circuit means responsive to said alternating component for supplying a fourth output signal only when said range falls below a predetermined value, and utilization means responsive only to the simultaneous presence of said second, third, and fourth output signals.