(19)

(11)

EP 0 799 523 A1

(12)

(43) Date of publication: 08.10.1997 Bulletin 1997/41 (21) Application number: 95941787.0 (22) Date of filing: 21.12.1995

(51) International Patent Classification (IPC):  H03D 7/ 16( . ) H04B 1/ 12( . ) H03F 1/ 32( . ) (86) International application number: PCT/GB1995/003000 (87) International publication number: WO 1996/019864 (27.06.1996 Gazette 1996/29)

(84) Designated Contracting States: DE ES FR GB IT SE (30) Priority: 21.12.1994 GB 19940025845 (71) Applicant: UNIVERSITY OF BRISTOL Clifton Bristol BS8 1TH (GB)

(72) Inventors: McGEEHAN, Joseph, Peter Corsham, Wiltshire SN13 9AY (GB) BEACH, Mark, Anthony Langford, Bristol BS18 7HP (GB) KENINGTON, Peter, Blakeborough Winterbourne, Bristol BS17 1PX (GB) NIX, Andrew, Robert, University of Bristol, RSIOL Clifton, Bristol BS8 1TH (GB) (74) Representative: O'Connell, David Christopher  Haseltine Lake & Co., Imperial House, 15-19 Kingsway London WC2B 6UD London WC2B 6UD (GB)