Optics: measuring and testing – Range or remote distance finding – With photodetection
Patent
1987-03-19
1990-01-23
Tarcza, Thomas H.
Optics: measuring and testing
Range or remote distance finding
With photodetection
356 45, 356 285, 367101, G01C 308, G01S 968
Patent
active
048954411
ABSTRACT:
An improved method and apparatus for precision ranging is described using a frequency-modulated signal source to stimulate creation of interference fringes at a rate proportional to absolute distance to a target. According to the invention, a low frequency modulating signal modulates a relatively high frequency signal source having a predetermined long coherent length compared to the distance to be measured. The resulting frequency-modulated signal is transmitted to the target to generate a reflected version thereof. Because of the long coherent length of the signal source, the transmitted frequency-modulated signal maintains spatial coherence as it travels to and from the target. Moreover, the low frequency modulating signal stimulates production of 360.degree. instantaneous phase differences between the transmitted and received frequency-modulated signals when these signals are superimposed. The number of these 360.degree. phase differences per period of the modulating signal is proportional to a time-of-flight of the transmitted frequency-modulated signal to and from the target and thus absolute distance. In operation, the transmitted and received frequency-modulated signals are logically compared by a balanced demodulator to generate a beat frequency signal from which the number of 360.degree. phase differences per period of the modulating signal is extracted. The beat frequency signal is then processed to determine the distance to the target. Preferably, a reference circuit is used to maintain the frequency stability of the signal source.
REFERENCES:
patent: 2537593 (1951-01-01), Landon et al.
patent: 3140461 (1964-07-01), McKinney
patent: 3728025 (1973-04-01), Madigan et al.
patent: 3779645 (1973-12-01), Nakazawa et al.
patent: 3825340 (1974-07-01), Debart
patent: 3997866 (1976-12-01), Taylor et al.
patent: 4140060 (1979-02-01), Brenner
patent: 4360812 (1982-11-01), Peperone
patent: 4403857 (1983-09-01), Holscher
patent: 4443792 (1984-04-01), Pidgeon et al.
patent: 4472793 (1984-09-01), Bejaminson
patent: 4531833 (1985-07-01), Ohtomo
patent: 4656480 (1987-04-01), Allezard et al.
patent: 4712915 (1987-12-01), Kosakowski et al.
patent: 4721385 (1988-01-01), Jelalian et al.
patent: 4744040 (1988-05-01), Kawata et al.
Skolnik, M. I., "Frequency-Modulated CW Radar," Introduction to Radar Systems, McGraw-Hill Book Co., New York, 1980, pp. 81-92.
Judson David H.
Pandel Instruments, Inc.
Tarcza Thomas H.
Wallace Linda J.
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