| http://www.w3.org/ns/prov#value | - Cl. ..G0lc 3/08 Field of Search ..356/4, 5; 343/13, 343/75; 340/1 R, l C, l L [56] References Cited UNITED STATES PATENTS 3,503,680 3/1970 Schenkerman ..356/5 Primary Examiner-Benjamin A. Borchelt Assistant ExaminerS. C. Buczinski Attorney-Jennings Bailey, Jr. [ 5 7 ABSTRACT An arrangement for measuring distance under conditions when disturbances of various types may be expected to occur between t
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