(19)

(11)

EP 0 968 624 A2

(12)

(88) Date of publication A3: 17.12.1998 (43) Date of publication: 05.01.2000 Bulletin 2000/01 (21) Application number: 98909666.4 (22) Date of filing: 18.03.1998

(51) International Patent Classification (IPC)7: H04S 1/00 (86) International application number: PCT/GB9800/813 (87) International publication number: WO 9842/161 (24.09.1998 Gazette 1998/38)

(84) Designated Contracting States: CH DE FR GB LI NL SE (30) Priority: 18.03.1997 GB 9705565 19.04.1997 GB 9707962 (71) Applicant: CENTRAL RESEARCH LABORATORIES LIMITED Hayes,Middlesex, UB3 1HH (GB)	(72) Inventors: MONTEITH, David London N1 8JP (GB) SIBBALD, Alastair Maidenhead,Berkshire SL6 1XL (GB) TODD, Martin, Peter Uxbridge,Middlesex UB10 9NQ (GB) (74) Representative: Leaman, Keith et al QED I.P. Services Limited,Dawley Road Hayes,Middlesex UB3 1HH Hayes,Middlesex UB3 1HH (GB)