Patent ID: 8305265

Claim:
A radio-based navigation system for receiving selected radio-frequency signals of a known origin and a known waveform, and for determining the system position, velocity, three-dimensional attitude and time, said system comprising: a. a radio-frequency-to-digital front-end configured to accept a minimum of two feed signals from a direction-finding antenna having a maximum aperture dimension that is less than 0.7 wavelength at the lowest operating frequency and capable of supporting a minimum of two unchanging direction-finding modes that are substantially cylindrically symmetric about a single unchanging antenna boresight and to convert the feed signals to digital signals; and b. a receiver module configured to process said digital signals wherein said receiver module is configured to: (1) combine the digital signals to form a minimum of two direction-finding signals corresponding to said direction-finding modes; (2) thereafter combine the digital signals or the direction-finding signals to create at least one navigation signal such that said selected radio-frequency signals are enhanced and the effects of interference signals, if any, are reduced; (3) determine the system position, velocity, and time from said selected radio-frequency signals obtained from said at least one navigation signal; and (4) determine two-dimensional angles of arrival of said selected radio-frequency signals and thereby the system three-dimensional attitude from the direction-finding signals via simultaneous mode comparison techniques.