Abstract: A digitally coded output is provided from a sensor, such as an aircraft angle of attack sensor. Groups of unused words from the complete unit distance table are omitted between groups of words that are selected to be used in the code, these unused words being "illegal" words indicating an error if they appear in the output of the sensor. The digitally encoded output of the sensor is, in the preferred embodiment, in unit distance code, and is fed to a programmed ROM where it is converted to binary or other convenient code, this binary encoded information representing the sensor output being employed to convey the information provided thereby. The output of the sensor is also fed to a second programmed ROM which has information stored therein indicative of which of the code words are "illegal". Whenever an illegal word is fed to this second programmed ROM, it generates a digital output indicating an error.

Abstract: An exit illuminating system for illuminating an exit or exit sign with high intensity light under emergency conditions, the light having sufficient brilliance to be visible through smoke in order to lead persons who may be trapped in the smoke-filled area to the escape exit. The system incorporates an emergency condition detector responsive to power failure, smoke and heat in order to develop an activating signal which energizes a high intensity xenon flash lamp. The system is made fail-safe by a circuit which causes a battery to power the flash lamp if line power is lost and which keeps the battery at full charge when external power is available.

Abstract: The output of a transducer providing a signal in accordance with the instantaneous air speed of an aircraft is differentiated and fed to a summing device which subtracts therefrom a signal in accordance with the horizontal acceleration of the aircraft, this signal being derived from the output of an inertial instrument such as an accelerometer. The output of the summing device represents the magnitude of the wind shear condition (rate of change of wind velocity with changes in altitude). This signal is fed to appropriate indicator means which may comprise an appropriate display, a peak magnitude storage device, a warning device indicating a dangerous wind shear condition, or a telemetering device providing a wind shear reading to a ground station for use in advising other aircraft.