Abstract: A very high frequency omni-range (VOR) receiver for use in aircraft radio-navigation, which provides an indication of course deviation that is substantially immune to effects such as reflections in transmitted VOR signals, transients occurring in an aircraft's electrical system and propeller and/or rotor modulations of an incoming VOR signal and the like which are all unrelated to actual course deviation, is disclosed. The receiver phase synchronizes a signal from a 1.08 MHz crystal oscillator to a 30 Hz reference signal and a 30 Hz variable signal; both the reference and variable signals are received from a VOR ground station. As a result of the phase synchronization, the receiver produces timing pulses which are accurately phase synchronized to a synchronized reference pulse stream derived from the 30 Hz reference signal. Additionally, the receiver produces a synchronized variable pulse stream that is derived from the 30 Hz variable signal.

Abstract: A vertical speed indicator uses a substantially rigid hollow closed air chamber; a capillary tube having a reduced inside diameter connected to the chamber for routing atmospheric air from an aircraft static system at a reduced flow rate into the chamber; a differential pressure transducer having two inlet ports; a pneumatic conduit connecting the chamber and one of the ports of the transducer for exposing that port to internal chamber air pressure; a pneumatic conduit connected to the other port for exposing that port to atmospheric pressure occurring within the static system; and electronic processing circuitry connected to the transducer for providing an indication of the vertical speed of the aircraft.