(19)

(11)

EP 1 018 196 A1

(12)

(43) Date of publication: 12.07.2000 Bulletin 2000/28 (21) Application number: 98942918.8 (22) Date of filing: 14.09.1998

(51) International Patent Classification (IPC)7: H01S 3/25, H01S 3/0941, H01S 3/043 (86) International application number: PCT/GB9802/782 (87) International publication number: WO 9917/411 (08.04.1999 Gazette 1999/14)

(84) Designated Contracting States: DE FI FR GB (30) Priority: 26.09.1997 GB 9720376 (71) Applicant: GEC-MARCONI AVIONICS (HOLDINGS) LIMITED Stanmore,Middlesex HA7 4LY (GB)	(72) Inventor: HALL, Peter, Hutchinson Edinburgh EH5 3JA (GB) (74) Representative: Fitchett, Stuart Paul  Marconi Intellectual PropertyWaterhouse Lane Chelmsford,Essex CM1 2QX Chelmsford,Essex CM1 2QX (GB)