(19)

(11)

EP 0 427 831 A1

(12)

(43) Date of publication: 22.05.1991 Bulletin 1991/21 (21) Application number: 90907200.0 (22) Date of filing: 03.05.1990

(51) International Patent Classification (IPC):  B64D 11/ 00( . ) H04N 7/ 173( . ) H04H 20/ 69( . ) (86) International application number: PCT/GB1990/000681 (87) International publication number: WO 1990/015508 (13.12.1990 Gazette 1990/28)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB IT LI LU NL SE (30) Priority: 31.05.1989 GB 19890012474 (71) Applicant: GEC-MARCONI LIMITED Stanmore, Middlesex HA7 4LY (GB)

(72) Inventors: McSPIRIT, Charles Hampshire P011 9PZ (GB) WADE, John, Gordon Havant Hampshire P09 2UT (GB) HARVEY, Colin, Micheal Hampshire P011 ONY (GB) SPRIGGS, Timothy, John Hayling Island P011 ONJ (GB) (74) Representative: Vaufrouard, John Charles, et al  The GEC Patent Department(Chelmsford Office) GEC-Marconi Research Centre West Hanningfield Road Great Baddow, Essex CM2 8HN Great Baddow, Essex CM2 8HN (GB)