Near range obstacle detection and ranging aid

Claim 1

Range detection apparatus comprising: (a) means for generating high frequency energy over a finite frequency range and for frequency modulating over a limited range of bandwidth said high frequency energy and for supplying said frequency-modulated high frequency energy to a first electrical path providing a phase reference, (b) a second electrical path for transmission and receiving and including means for radiating said frequency modulated high frequency energy into space in the form of propagating waves and for receiving a portion of said radiated energy after reflection from a remote object, said energy portion acquiring a phase shift related to the distance traveled by said radiated energy and to the frequency of said radiated energy, (c) means in one of said paths for phase shifting said frequency-modulated high frequency energy at a plurality of predetermined frequency values over a finite frequency range of said bandwidth and at a predetermined plurality of phase-shifting values having a certain quantity greater than two, and at combinations of said phase-shifting and said frequency values to improve by a factor of said certain quantity the relative range resolution attainable with said limited range of bandwidth, (d) and means for comparing the phase of said frequency-modulation energy in one of said paths with the phase of said reflected and received radiated energy in the other of said paths to produce range measurement signals related to the combined phase shifts of said two paths and in accordance with said signals produced by said phase comparing means, and with the combinations of phase states of said phase shifter and the frequencies of said energy generating means, (e) and means for deriving range measurement information from all of said phase-shifting and said frequency values.