Vehicle speed sensor for skid control system

Claim 2

A vehicle speed sensor for a skid control system for a wheeled vehicle having a source of electrical power and a brake pedal, comprising; a doppler radar system operatively mounted on the vehicle to produce an electrical speed signal having a voltage analogous to the speed of the vehicle when connected to the source; and a first switch operative to connect said doppler radar system to the source when the brake pedal is depressed.

Claim 3

A vehicle speed sensor as claimed in claim 1, further comprising switch means responsive to a plurality of operating parameters of said doppler radar system and operative to pass said speed signal therethrough to the skid control system only if the values of said purality of operating parameters correspond to a predetermined pattern indicating normal operation of said doppler radar system.

Claim 4

A vehicle speed sensor as claimed in claim 2, in which said switch means comprises an actuator responsive to said plurality of operating parameters and a second switch controlled thereby.

Claim 5

A vehicle speed sensor as claimed in claim 3, in which said doppler radar system comprises a doppler radar operative to produce an electrical doppler signal having a frequency analogous to the speed of the vehicle, and a converter to convert said doppler signal to said speed signal.

Claim 6

A vehicle speed sensor as claimed in claim 4, in which said actuator has a first input connected to a junction between said first switch and said doppler radar system, a second input connected to a junction between said doppler radar and said converter, and a third input connected to the output of said converter; signals at said first, second and third inputs thus constituting said operating parameters of said doppler radar system and said actuator being operative to actuate said second switch in response to said predetermined pattern thereof.

Claim 7

A vehicle speed sensor as claimed in claim 5, in which said actuator comprises a first OR gate having inputs thereof connected respectively to said first, second and third inputs, an AND gate having inputs connected respectively to said first and second inputs, an inverter having an input connected to the output of said first OR gate, and a second OR gate having inputs connected to the outputs of said AND gate and said inverter.

Claim 8

A vehicle speed sensor as claimed in claim 3, further comprising an alarm which is energized when said first switch is closed and said second switch is open.