EP 1777988 A3 20080528 - Improvements to a public address system having zone isolator circuits
Title (en)
Improvements to a public address system having zone isolator circuits
Title (de)
Verbesserungen an einem Beschallungssystem mit Gebietsisolatorsschaltungen
Title (fr)
Améliorations apportées à un système d'annonce en public avec circuits isolateurs de zone
Publication
Application
Priority
GB 0521337 A 20051020
Abstract (en)
[origin: EP1777988A2] A public address network includes a driver unit (11) that comprises a high pass circuitry pass and a low pass circuitry pass. The high pass part drives an audio signal (14) on to a pair of signal wires (12). The low pass part comprises a gyrator circuit that drives a pilot signal (15) on to the pair of signal wires (12). The signal wires transmit the audio signal and deliver it to one or more audio output units (16). The signal wires also transmit the pilot signal and deliver it to one or more isolator circuits (20). Each isolator circuit is arranged to operatively isolate a section of the signal wires.
IPC 8 full level
H04R 27/00 (2006.01); H04R 29/00 (2006.01); H04R 3/12 (2006.01)
CPC (source: EP GB)
H04R 27/00 (2013.01 - EP GB); H04R 29/00 (2013.01 - GB); H04R 29/007 (2013.01 - EP); H04R 3/12 (2013.01 - EP)
Citation (search report)
- [DA] EP 0967833 A2 19991229 - PROTEC FIRE DETECTION PLC [GB]
- [A] GB 523057 A 19400704 - GUIDED RADIO CORP
- [A] US 2004184598 A1 20040923 - HOLCOMBE WAYNE T [US], et al
Designated contracting state (EPC)
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
Designated extension state (EPC)
AL BA HR MK RS
DOCDB simple family (publication)
EP 1777988 A2 20070425; EP 1777988 A3 20080528; EP 1777988 B1 20090812; AT E439744 T1 20090815; DE 602006008402 D1 20090924; GB 0521337 D0 20051130; GB 2432091 A 20070509; GB 2432091 B 20090617
DOCDB simple family (application)
EP 06255349 A 20061017; AT 06255349 T 20061017; DE 602006008402 T 20061017; GB 0521337 A 20051020