Abstract: A gas measuring method, apparatus and system for measuring a concentration of a gas of interest is disclosed. The gas concentration is based on a propagation delay of a sonic or ultrasonic wave as the wave travels through the gas. The propagation delay is measured such that delay contributions from sources other than the gas itself are canceled. A sensor in accordance with the invention includes an sonic or ultrasonic transmitter and receiver, and a control module for performing calculations. The sensor can be used in various applications, including on-board inert gas generating systems (OBIGGS).

Abstract: A gas measuring method, apparatus and system for measuring a concentration of a gas of interest is disclosed. The gas concentration is based on a propagation delay of a sonic or ultrasonic wave as the wave travels through the gas. The propagation delay is measured such that delay contributions from sources other than the gas itself are canceled. A sensor in accordance with the invention includes an sonic or ultrasonic transmitter and receiver, and a control module for performing calculations. The sensor can be used in various applications, including on-board inert gas generating systems (OBIGGS).

Abstract: An optical communications link for an electrical communications system, e.g., an ARINC 429 protocol system, includes a first logic device to convert an input signal of a given level to a first electrical signal of a duration corresponding to such level, a first optical device (transmitter) presenting an optical signal of a duration corresponding to such first electrical signal, a second optical device (receiver) to convert the optical signal to a second electrical signal of a duration representative of the duration of the optical signal, an optical coupling between the optical devices, and a second logic device to convert the second electrical signal to an output electrical signal having a level representative of the duration of the optical signal. A communications system including electrical communications input and output devices, the optical and an optical communications link coupled between those devices.