(19)

(11)

EP 0 033 340 A1

(12)

(43) Date of publication: 12.08.1981 Bulletin 1981/32 (21) Application number: 80901618.0 (22) Date of filing: 31.07.1980

(51) International Patent Classification (IPC):  G01C 19/ 60( . ) (86) International application number: PCT/US1980/000972 (87) International publication number: WO 1981/000455 (19.02.1981 Gazette 1981/05)

(84) Designated Contracting States: CH DE FR GB LI SE (30) Priority: 01.08.1979 US 19790062662 (71) Applicant: HUGHES AIRCRAFT COMPANY Los Angeles, California 90045-0066 (US)	(72) Inventor: WANG, Harry T. M. Thousand Oaks, CA 91360 (US)