An indication of altitude variation about a preselected altitude is provided from a real-time altitude digital code information input signal in response to an altitude alert control signal which is proportional to a first pair of complementary sinusoidal functions of the altitude variation. A second pair of complementary sinusoidal functions of altitude is provided from the altitude digital input signal. The first pair of sinusoidal functions is a function of the second pair of sinusoidal functions and the preselected altitude. A digital-to-synchro conversion for the input signal is provided by means of a pair of read-only memories which have been programmed to each provide a complementary sinusoidal function of the input and a binary scaling means, such as an R-2R ladder network connected to the outputs of each of the respective memories, whereby the second pair of complementary signals is provided. Each memory has an operating state and a protection state, an output being producible only in the operating state. A source of reference potential which has a value sufficient to maintain the memories in the operating state is connected to the scaling means. A single-shot which includes an operational amplifier and a capacitive charging network for changing the input potentials to the operational amplifier to turn it on and off is included as a trigger for an alert indication in response to a particular condition of the altitude alert control signals.
An aircraft altitude alerting instrument. The instrument includes a pressure reference scale and an altitude alerting scale. Means is provided for placing a selected altitude alerting setting on the altitude scale adjacent to a pressure reference reading on the pressure reference scale. The pressure reference reading on the pressure reference scale provides an index for the selected altitude alerting setting. Means responsive to measured static pressure outside the aircraft and coupled to the altitude setting means is provided for activating a warning signal device.
A system for providing a digital display of aircraft altitude, a selected altitude which it is desired the aircraft to assume and when the selected altitude is achieved, an audio and visual indication is produced. When within 1000 feet of the selected altitude, the visual indication gives the direction the aircraft must continue (i.e., up or down). When the aircraft exceeds a prescribed range, either above or below the selected altitude, an audio signal is produced. Barometric pressure obtained from air traffic control may be entered into the system and the measured altitude displayed will be automatically corrected.
An integrated display for either alternately or simultaneously displaying pressure derived barometric altitude and radar altimeter readings within a single display structure. Barometric altitude is displayed on a dual-counter and drum and a dial face and pointer to provide a barometric altitude reading and to further provide analog trending information. Radar altitude is displayed in a multi-segment filament or light emitting diode device. Means are provided for automatically energizing the radar altitude display at and below a predetermined altitude. Integration of the displays into a single indicator structure saves valuable panel space within a most critical area of the aircraft instrument panel. Circuitry is provided to generate a visual and/or audible alarm when the radar altitude is equal to or below the minimum decision height (MDH). The two altitude readings, i.e., pressure and radar derived, serve as accuracy checks on one another.
An apparatus and method for automatically and independently determining aircraft altitude and alerting the pilot to deviations from a target altitude exceeding a specified tolerance. The alerter comprises an altitude sensing means for sensing the present altitude of the aircraft. The invention discloses three sources for altitude information namely, a self-contined sensor such as a pressure transducer, a Global Positioning System receive, or an altitude encoder. A target entry means is used for entering the target altitude. An indicating means signals an altitude alerting condition upon the detection of a condition wherein the absolute difference is larger than the tolerance value. The altitude alerting apparatus may also comprise a display means for display of the present aircraft altitude information.
