(19)

(11)

EP 0 876 706 A1

(12)

(43) Date of publication: 11.11.1998 Bulletin 1998/46 (21) Application number: 97901200.0 (22) Date of filing: 27.01.1997

(51) International Patent Classification (IPC):  H03H 21/ 00( . ) H04L 25/ 03( . ) (86) International application number: PCT/GB1997/000234 (87) International publication number: WO 1997/027671 (31.07.1997 Gazette 1997/33)

(84) Designated Contracting States: DE FR GB IT SE (30) Priority: 25.01.1996 GB 19960001491 (71) Applicant: UNIVERSITY OF BRISTOL Clifton Bristol BS8 1TH (GB)	(72) Inventors: BULL, David Roger Chepstow, Gwent NP6 7JE (GB) NIX, Andrew Robert Clifton, Bristol BS8 1THH (GB) PERRY, Russell Almondsbury, Bristol BS12 4EZ (GB) (74) Representative: O'Connell, David Christopher, et al  Haseltine Lake & Co., Imperial House, 15-19 Kingsway London WC2B 6UD London WC2B 6UD (GB)