EP0967833B1 - Ein Verfahren zum Betreiben eines Beschallungssystems mit Gebietsisolatorschaltungen - Google Patents

Ein Verfahren zum Betreiben eines Beschallungssystems mit Gebietsisolatorschaltungen Download PDF

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Publication number
EP0967833B1
EP0967833B1 EP19990305005 EP99305005A EP0967833B1 EP 0967833 B1 EP0967833 B1 EP 0967833B1 EP 19990305005 EP19990305005 EP 19990305005 EP 99305005 A EP99305005 A EP 99305005A EP 0967833 B1 EP0967833 B1 EP 0967833B1
Authority
EP
European Patent Office
Prior art keywords
signal
pilot signal
audio
isolator
wires
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19990305005
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English (en)
French (fr)
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EP0967833A2 (de
EP0967833A3 (de
Inventor
Eric c/o Protec Fire Detection Plc Priest
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Protec Fire Detection PLC
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Protec Fire Detection PLC
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Filing date
Publication date
Application filed by Protec Fire Detection PLC filed Critical Protec Fire Detection PLC
Publication of EP0967833A2 publication Critical patent/EP0967833A2/de
Publication of EP0967833A3 publication Critical patent/EP0967833A3/de
Application granted granted Critical
Publication of EP0967833B1 publication Critical patent/EP0967833B1/de
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R29/00—Monitoring arrangements; Testing arrangements
    • H04R29/007—Monitoring arrangements; Testing arrangements for public address systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R27/00—Public address systems

Definitions

  • the present invention relates in general to a public address system and in particular, but not exclusively, to a public address system used as a voice alarm speaker network in conjunction with a fire or safety alarm system.
  • a public address system comprises a plurality of speakers positioned at convenient locations around building or other site, each coupled to a central control unit including an audio amplifier for driving a audio signal to the speaker units. It is desired to minimise the amount of wiring in a system, in order to minimise cost and complexity and to improve long term reliability. Ideally, it is desired to use a single pair of signal wires coupled to each speaker unit, with the speaker units typically being coupled across the signal wires in parallel. Using a single pair of signal wires minimises cabling costs and aids discrete installation. However, this arrangement has minimal redundancy and a fault such as a short circuit may occur at any point along the signal wires, leading to a malfunction of the system.
  • a short circuit fault generally means that the system must be shut down in order to avoid damage to sensitive components, such as the audio amplifier.
  • An open circuit fault for example due to an accidental break in the signal wires, can often be tolerated, but loud speakers positioned after the break do not receive an audio signal.
  • German patent application DE 3627960C1 discloses a monitoring device for locating a loudspeaker failure for an installation comprising a number of loudspeakers which are in each case allocated a fault detector and a test circuit.
  • British patent application GB2299238A discloses a public address system, having a thermistor or other device with a positive resistance/temperature characteristic in series with each loudspeaker to limit current in the event of a short circuit fault, thereby enabling the other speakers to continue
  • a public address network for producing an audible signal from a plurality of loud speaker units.
  • a public address network can be used to warn of an alarm condition and give information to the occupants of a building.
  • a preferred schematic layout is shown for a network 10 comprising a control station 11 having an amplifier for driving an audio signal 14 and a pilot signal 15 on to signal wires 12.
  • the signal wires 12 are divided into sections 12a, 12b, etc., by isolators 20. Each section is provided with one or more loud speaker units 16 or other devices.
  • the pilot signal 15 is detected by each isolator unit 20 which, in response, completes the signal path between relevant sections e.g. 12a, 12b of the signal wires.
  • a successful operating condition is determined when the pilot signal 15 reaches an end of line monitor 13.
  • the audio signal 14 is supplied to each of the speaker units 16 arranged in parallel across the signal wires 12 such that, for example, an alarm message is heard simultaneously throughout a building.
  • each isolator unit 20 is of identical construction.
  • the isolator unit 20 comprises a relay 21 whose contacts are arranged to lie in a signal path between an input coupled to a first signal wire section 12a and an output coupled to a second signal wire section 12b.
  • the signal wires 12a and 12b form adjacent sections to the isolator unit 20.
  • the relay 21 operates in accordance with a control signal from a relay driver circuit 22 which is coupled to a short circuit detector unit 23.
  • the short circuit detector 23 comprises a voltage sensor for determining the load current drawn by an output section of the isolator, i.e. on the signal wires 12b.
  • the short circuit detector is arranged to sense voltage developed across both the output load 12b and the input load 12a, such that the isolator circuit may operate bidirectionally.
  • the signal wires 12 carry both an audio signal 14 and a pilot signal 15.
  • the pilot signal is preferably a non-audio signal such as a subsonic or supersonic signal, and ideally a direct current signal.
  • each isolator unit comprises means for detecting the pilot signal 15, suitably a low pass filter 24.
  • the low pass filter 24 recovers the direct current component from the signals received at the input 12a to produce a direct current power supply, suitably of around 50 volts DC.
  • the active current source (or constant current generator) 221 supplies a predetermined constant current through a relay driver 222 to the coil of a relay 21 to keep the normally open contacts thereof closed and thereby complete the signal path.
  • the constant current generator 221 provides a current of about 10 milliamps thereby underrunning the coil of relay 21.
  • less power is dissipated and relay life expectancy is improved despite the relay coil being powered for most of the time in a normal operating condition.
  • pilot signal 15 is not present at the input 12a to the isolator 20
  • no power supply is provided through the low pass filter 24 and the contacts of relay 21 remain open to interrupt the signal path through the isolator.
  • the relay driver 222 When the short circuit detector 23 detects a short circuit on the output line 12b, the relay driver 222 is switched to divert current from the coil of relay 21, thereby opening the contacts of the relay and interrupting the signal power through the isolator.
  • the DC pilot signal 15 can be obtained from the first signal wire input 12a through a first low pass filter comprising inductor L1 and capacitor C2, or from the second signal wire input 12b through a second low pass filter comprising a second inductor L2 and a second capacitor C3.
  • the DC pilot signal is supplied to power the remainder of the isolator circuit through a diode OR gate formed from diodes D1 and D2.
  • the inductors L1 and L2 preferably have an inductance of approximately 90H, i.e. a relatively large value, to minimise loading of the isolator circuit on the audio components of the network.
  • the short circuit detector 23 comprises an AND gate formed of diodes D4 and D6 coupled to either side of the isolator 12a and 12b. Therefore, a single short circuit detector can be used, comprising zener diode Z1, bias resister R1 and power transistor T1. The relay 21 is closed only if the short circuit detector 23 detects a high resistance on both sides of the isolator 20, and, otherwise, the relay remains open.
  • the audio signal 14 is driven onto the signal wire loop 12 through a transformer TX1.
  • the transformer TX1 is a 100V line transformer taking an audio signal input from an audio amplifier 114 and providing this to both ends of the signal line loop 12.
  • a pilot signal driver 115 is used to superimpose the pilot signal, in this example a DC signal of about 65 volts, onto the loop 12 alongside the audio signal 14.
  • Each loudspeaker unit 16 on the loop 12 filters out the pilot signal 15, such as by using a decoupling capacitor, to leave only the audio signal 14. Therefore, the pilot signal 15 does not affect the audio signal 14.
  • the pilot signal 15 travels from one end only all the way along the signal line loop 12 to reach an end of line monitor 13 which produces a normal condition signal and operator feedback, such as a green LED.
  • a control circuit 14 provides operator feedback, such as a red LED, and closes line relays RLA1 and RLA2. As shown in Figure 5 , closing relays RLA1 and RLA2 connects both ends of the loop 12 (shown as A and A', and B and B', respectively) such that the pilot signal 15 is now supplied to both ends of the loop 12. The network is therefore able to detect an open circuit fault and maintain full operation.
  • the control circuit 14 comprises a global overcurrent trip detector 141 for detecting a short circuit on the network. If a short circuit is detected by the overcurrent trip circuit 141 or if the pilot signal does not reach the end of line circuit 13, the control circuit 14 causes the network to be shutdown, thereby avoiding possible damage to sensitive components such as the audio amplifier 114. The pilot signal 15 no longer reaches any of the isolators 20, each of which thereby isolate respective sections of the signal wire loop 12.
  • reboot circuit 143 causes the pilot signal 115 and the audio signal 114 to be reapplied to the signal loop 12.
  • the isolators 20 will each in turn assess adjacent sections of the signal loop 12 for the short circuit fault, and reconnect the signal path only if the short circuit fault does not occur in the adjacent line sections. For example, referring again to Figure 1 , isolator 20b tests for a short circuit in sections 12a and 12b and will connect the signal path 12a to 12b only if no short circuit is detected.
  • line relay control circuit 142 will, in this fault condition, close line relays RLA1 and RLA2 such that the pilot signal 15 is driven from both ends of the loop 12.
  • the pilot signal 15 and the audio signal 14 thereby reach all parts of the signal loop 12, except for the section containing the short circuit fault which is isolated by isolator units 20 at either side thereof.
  • a public address network has been described which detects and tolerates open circuit and short circuit fault conditions safely and economically, and which maintains operation of the network despite such fault conditions. Minimal additional circuitry is required, and, advantageously, only a single pair of signal wires are required.

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Alarm Systems (AREA)

Claims (2)

  1. Verfahren zum Betreiben eines Rundrufnetzes, das einen seriellen Signalpfad besitzt, der ein Paar Signaldrähte (12), die mit einer oder mehreren Audioausgabeeinheiten (16) gekoppelt sind, und einen oder mehrere Isolatoren (20), um Abschnitte der Signaldrähte (12) zu isolieren, enthält, das die folgenden Schritte umfasst:
    Schicken eines Audiosignals (14) von einem Ende in die Signaldrähte (12), um es den Audioausgabeeinheiten (16) zuzuführen;
    Schicken eines Vorsteuersignals (15) von dem einen Ende in die Signaldrähte (12), um es den Isolatoren (20) zuzuführen;
    Detektieren des Vorsteuersignals an dem anderen Ende des seriellen Signalpfads unter Verwendung eines Endes eines Leitungsdetektors (13);
    falls das Vorsteuersignal (15) an dem Ende des Leitungsdetektors (13) nicht vorhanden ist, Schicken des Audiosignals (14) und des Vorsteuersignals (15) von beiden Enden des Audiosignalpfads.
  2. Verfahren nach Anspruch 1, das ferner die folgenden Schritte umfasst:
    Schicken des Audiosignals (14) und des Vorsteuersignals (15), um die Isolatoren (20) mit Leistung zu versorgen, in ein zweites Ende der Signaldrähte (12) entfernt von dem ersten Ende; und
    falls das Vorsteuersignal (15) an dem Ende des Leitungsdetektors (13) nicht vorhanden ist, Beseitigen des Audiosignals (14) und des Vorsteuersignals (15) von dem ersten Ende und dann Schicken des Audiosignals (14) und des Vorsteuersignals (15) in das erste und in das zweite Ende der Signaldrähte (12).
EP19990305005 1998-06-27 1999-06-25 Ein Verfahren zum Betreiben eines Beschallungssystems mit Gebietsisolatorschaltungen Expired - Lifetime EP0967833B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9813882 1998-06-27
GBGB9813882.9A GB9813882D0 (en) 1998-06-27 1998-06-27 Public address system having zone isolator circuits

Publications (3)

Publication Number Publication Date
EP0967833A2 EP0967833A2 (de) 1999-12-29
EP0967833A3 EP0967833A3 (de) 2004-03-17
EP0967833B1 true EP0967833B1 (de) 2012-10-24

Family

ID=10834486

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19990305005 Expired - Lifetime EP0967833B1 (de) 1998-06-27 1999-06-25 Ein Verfahren zum Betreiben eines Beschallungssystems mit Gebietsisolatorschaltungen

Country Status (2)

Country Link
EP (1) EP0967833B1 (de)
GB (1) GB9813882D0 (de)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006050754A2 (en) * 2004-11-09 2006-05-18 Robert Bosch Gmbh Public address system
GB2432091B (en) * 2005-10-20 2009-06-17 Protec Fire Detection Plc Improvements to a public address system having zone isolator circuits
FR2895203B1 (fr) * 2005-12-21 2008-02-29 Chantiers De L Atlantique Sa Dispositif de sonorisation et navire comportant le dispositif
DE102010028022A1 (de) * 2010-04-21 2011-10-27 Robert Bosch Gmbh Verfahren und Einrichtung zur Überwachung einer Lautsprecherlinie
DE102010047220B4 (de) * 2010-10-04 2012-07-05 Novar Gmbh Verfahren zum Betreiben einer Sprachdurchsageanlage
NL2006494C2 (en) 2011-03-25 2012-09-26 Astrea Intellectueel Eigendomsrecht B V Isolator device for passing through a signal.
EP2875652B1 (de) * 2012-07-20 2019-12-04 Toa Corporation Öffentliches adresssystem lautsprecheranlage und überwachungsvorrichtung für eine öffentliches adresssystem lautsprecheranlage
ES2916348T3 (es) 2017-08-11 2022-06-30 Carrier Corp Localización de fallos a tierra

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3989908A (en) * 1975-06-26 1976-11-02 General Signal Corporation Speaker supervision in a public address system
DE3627960C1 (en) * 1986-08-18 1987-09-03 Philips Patentverwaltung Monitoring device for loudspeaker installations
GB2299238B (en) * 1995-03-22 1997-06-11 Audix Communications Limited Loudspeaker and loudspeaker system

Also Published As

Publication number Publication date
EP0967833A2 (de) 1999-12-29
EP0967833A3 (de) 2004-03-17
GB9813882D0 (en) 1998-08-26

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