Abstract: An integrated dual antenna system for Global Positioning System (GPS), Local Area Augmentation System (LAAS), ground based subsystem surface mounted (pole/tower/platform/other) and coaxially stacked (over and under). The dual antenna and receiver system is specifically designed and tuned to receive only the direct GPS satellite ranging signals while highly rejecting the ground multipath (indirect) signals. The upper antenna is a Right Hand Circularly Polarized (RHCP) omni-directional High Zenith Antenna (HZA) with dual obstruction lights and dual air terminals. The lower antenna is an electrically long vertically polarized omni-directional linear phased array having a very sharp horizon cut off and is a Multipath Limiting Antenna (MLA). When the two antennas (MLA and HZA) are mounted together they become the Integrated Multipath Limiting Antenna (IMLA). Interoperability is assured by high RF isolation between antennas.

Abstract: A dynamic voice operated filtering system for aircraft applications includes an input limiter, an expander, an output limiter and a user control. The input limiter receives an input signal representing a mixed voice and noise signal and filters the input signal. The input limiter outputs an attenuated version of the input signal (INL) to the expander. The input limiter attenuates the input signal so that the signal INL received by the expander remains within the expander's dynamic range. The expander outputs a signal INX, which represents an expanded version of signal INL. The signal INX has an amplitude that is a function of the amplitude of signal INL. The expander is configured to attenuate signal INL to serve as signal INX when the signal INL has a relatively low amplitude and amplifies signal INL to serve as the signal INX when the signal INL has a relatively high amplitude. The output limiter then receives the signal INX and, in response, filters the signal INX.