| 摘要 |
A method and apparatus for use in a pulse-echo imaging or ranging system comprising means (32) for identifying the analytic signal from a received signal and means (34) for extracting ranging information from the analytic signal. The analytic signal can be obtained and processed by digital or by analog circuit means. One embodiment of the analog circuit means (32) includes means (90) for modulating the received signal on a carrier frequency, means (92) for obtaining a single sideband signal from the modulated signal and means (94) for envelope detecting the single sideband signal. Another embodiment of the analog circuit means (32) includes various means (60), using coherent modulation techniques, for obtaining the quadrature components of the received signal, means (62) for squaring each of the quadrature components, means (64) for obtaining the sum of the squared quadrature components, and, if desired, means (66) for obtaining the square root of the sum, which is the magnitude of the complex analytic signal.
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