초록 ▼

A passive radio frequency signal-enabled aircraft altimeter employing signals of one or more global position system satellites as a source of terrain illumination. The altimeter determines altitude of the host aircraft with respect to specific terrain features beneath the aircraft rather than an alt

A passive radio frequency signal-enabled aircraft altimeter employing signals of one or more global position system satellites as a source of terrain illumination. The altimeter determines altitude of the host aircraft with respect to specific terrain features beneath the aircraft rather than an altitude above a mean or nominal level of the earth's surface--as is already provided in a global position system signal. The altimeter employs two signal paths between the global position system satellite and the host aircraft, one direct signal path and one earth-reflected signal path, together with elementary geometric/trigonometric relationships, involving length difference in these paths and signal angle of arrival, in determining aircraft altitude. Equal angles of satellite signal incidence and reflection at the point of satellite signal reflection from the earth is an enabling principle in the altimeter.

대표청구항 ▼

[ What is claimed is:] [1.]1. In combination:a host aircraft having first and second global position system signal reception antennas disposed on opposite extremities thereof, said first and second antennas having direct signal and earth-reflected signal reception capabilities respectively with resp

[ What is claimed is:] [1.]1. In combination:a host aircraft having first and second global position system signal reception antennas disposed on opposite extremities thereof, said first and second antennas having direct signal and earth-reflected signal reception capabilities respectively with respect to radio frequency signals originating in a global position system satellite;radio frequency signal receiver apparatus connected with said first and second global position system signal reception antennas and generating output signals representing first and second samples of global position system data received from said global position system satellite via said first and second antennas respectively;signal processing apparatus connected with said radio frequency signal receiver apparatus and generating, from said first and second samples of global position system data, first distance signals representative of direct physical distance between said aircraft first global position system signal reception antenna and said satellite and second distance signals representative of greater ground reflection-inclusive indirect physical distance between said aircraft second global position system signal reception antenna and said satellite;said second distance signals representative of greater ground reflection-inclusive indirect physical distance between said aircraft second global position system signal reception antenna and said satellite including equal-angled incident and reflected signal paths to and from an earth point of satellite signal illumination attending said aircraft;geometric algorithm signal processing apparatus generating from said first and second distance signals and angular relationships attending said equal-angled incident and reflected signal paths an aircraft altitude signal representative of orthogonal distance between said aircraft and a ground point below said aircraft.