(19)

(11)

EP 0 569 574 A1

(12)

(43) Date of publication: 18.11.1993 Bulletin 1993/46 (21) Application number: 92923933.0 (22) Date of filing: 27.11.1992

(51) International Patent Classification (IPC):  G01N 1/ 22( . ) G01N 33/ 543( . ) G01N 35/ 00( . ) G01N 33/ 53( . ) G01N 1/ 02( . ) (86) International application number: PCT/GB1992/002200 (87) International publication number: WO 1993/011430 (10.06.1993 Gazette 1993/14)

(84) Designated Contracting States: AT CH DE FR IT LI NL (30) Priority: 27.11.1991 GB 19910025218 (71) Applicant: GEC-MARCONI LIMITED Stanmore, Middlesex HA7 4LY (GB)	(72) Inventors: ABUKNESHA, Ramadan, Arbi London NW6 1DP (GB) BYFIELD, Mark, Philip Wexham Slough Berkshire SL2 5QW (GB) (74) Representative: George, Sidney Arthur  The General Electric Company p.l.c. GEC Patent Department Waterhouse Lane Chelmsford, Essex CM1 2QX Chelmsford, Essex CM1 2QX (GB)