(19)

(11)

EP 0 354 233 A1

(12)

(43) Date of publication: 14.02.1990 Bulletin 1990/07 (21) Application number: 89901578.0 (22) Date of filing: 12.01.1989

(51) International Patent Classification (IPC):  H03L 7/ 18( . ) H03L 7/ 089( . ) H03L 7/ 093( . ) H03L 7/ 087( . ) H03L 7/ 091( . ) (86) International application number: PCT/GB1989/000023 (87) International publication number: WO 1989/006881 (27.07.1989 Gazette 1989/16)

(84) Designated Contracting States: DE FR IT NL (30) Priority: 13.01.1988 GB 19880000723 05.05.1988 GB 19880010570 (71) Applicant: PLESSEY OVERSEAS LIMITED Ilford Essex IG1 4AQ (GB)	(72) Inventors: COWLEY, Nicholas, Paul Wroughton Wiltshire (GB) McCLELLAND, Thomas, David, Stephen Swindon Wiltshire (GB) (74) Representative: Elliott, Frank Edward  The Plessey Company plc. Intellectual Property Department Vicarage Lane Ilford, Essex IG1 4AQ Ilford, Essex IG1 4AQ (GB)