(19)

(11)

EP 0 298 090 A1

(12)

(43) Date of publication: 11.01.1989 Bulletin 1989/02 (21) Application number: 87907617.0 (22) Date of filing: 27.11.1987

(51) International Patent Classification (IPC):  G01H 9/ 00( . ) G01R 33/ 032( . ) G01H 17/ 00( . ) (86) International application number: PCT/GB1987/000850 (87) International publication number: WO 1988/004032 (02.06.1988 Gazette 1988/12)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 27.11.1986 GB 19860028367 (71) Applicant: PLESSEY OVERSEAS LIMITED Ilford Essex IG1 4AQ (GB)	(72) Inventors: HENNING, Michael, Laurence Shepton Mallet Somerset (GB) LAMB, Christopher Gillingham Dorset (GB) HAVARD, David Sherborne Dorset (GB)