Braking system test circuit

Claim 1

In a braking system for an aircraft having antiskid control circuits associated with the brakes of the wheels thereof, the improvement, comprising: a digital processor; interface circuit means interconnected between said processor and the antiskid control circuits for exercising selected circuit functions of the antiskid control circuits under direction of said processor, sensing responses to said selected functions, and providing such responses to said processor for evaluation of the operability of the antiskid control circuits; and wherein said interface circuit means exercises said selected circuit functions by the application of stimuli which simulate actual responses in the antiskid control circuits resulting from the braking of the aircraft on a runway and wherein said interface circuit means comprises: first gating means for receiving excitation signals from said processor and applying such signals as inputs to selected test points on the associated antiskid control circuit; second gating means for receiving response signals from additional selected test points on the associated antiskid control circuit, said response signals resulting from said excitation signals, said second gating means passing said response signals to said processor; said first gating means comprising an analog switch connected to and addressed by said processor and converter circuit means interconnected between said processor and analog switch for converting digital excitation signals from said processor to states usable by the antiskid control circuits, said converter circuit means comprising both digital to analog and voltage to frequency converters; and said second gating means comprising an analog selector connected to and addressed by said processor, and an analog to digital converter interposed between said analog selector and processor for converting said response signals form an analog to digital form.