Pressure transducer cross-check system

Claim 1

In an aircraft instrument system capable of receiving a pair of content related pressure responsive signals for providing input signals based thereon to a controller for said system, said system controller being capable of providing an aircraft instrument control signal responsive to said input signals provided thereto; the improvement comprising a pair of parameter input means; a pair of pressure transducers operatively connected between said parameter input means and said system controller, each of said pressure transducers being connected to a different parameter input means of said pair and being capable of detecting a predetermined parameter associated with said parameter input means for providing a pressure responsive parameter signal to said system controller in accordance with said detected parameter, said detected parameters being related to each other in content whereby said pair of provided parameter signals are related to each other in content, said pair of pressure transducers being operatively connected to said system controller for selectively providing said related parameter signals as said input signals thereto, each of said pair of pressure transducers being a relatively low precision pressure transducer; a common relatively high precision pressure transducer as compared with said low precision pressure transducers, said common high precision pressure transducer being selectively operatively connected between said system controller and one of said pair of parameter input means; and valve means operatively connected between said pair of parameter input means, said pair of low precision pressure transducers and said common high precision pressure transducer for alternately connecting one of said pair of low precision pressure transducers to one of said parameter input means while connecting said common high precision pressure transducer to the other of said parameter input means for selectively alternately providing one of said pair of parameter input signals as a high precision pressure responsive input signal to said system controller on alternate cycles of said low precision pressure transducer pair in accordance with the cycling of said valve means, whereby each of said low precision pressure transducers is alternately periodically calibrated during the operation of said aircraft instrument system dependent on said common high precision pressure responsive input signal.