EP1777988B1 - Améliorations apportées à un système d'annonce en public avec circuits isolateurs de zone - Google Patents

Améliorations apportées à un système d'annonce en public avec circuits isolateurs de zone Download PDF

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Publication number
EP1777988B1
EP1777988B1 EP06255349A EP06255349A EP1777988B1 EP 1777988 B1 EP1777988 B1 EP 1777988B1 EP 06255349 A EP06255349 A EP 06255349A EP 06255349 A EP06255349 A EP 06255349A EP 1777988 B1 EP1777988 B1 EP 1777988B1
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EP
European Patent Office
Prior art keywords
signal
network
wires
reference voltage
pilot signal
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EP06255349A
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German (de)
English (en)
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EP1777988A3 (fr
EP1777988A2 (fr
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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    • 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
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers

Definitions

  • the present invention relates in general to improvements to a public address system and in particular, but not exclusively, to improvements 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 a 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.
  • EP0967833 provides a public address system having greater fault tolerance, whilst requiring minimal wiring and is designed to maintain operation despite a short circuit fault or an open circuit fault occurring on a single pair of signal wires.
  • an isolator circuit for use with signal wires, comprising: fault detection means for detecting a fault condition on the signal wires; and interrupt means for interrupting the signal wires, the interrupt means being responsive to the fault detection means.
  • the interrupt means comprises an isolator circuit locatable in series at a predetermined position along the signal wires and the fault detection means comprises switch means for switching to a fault detected state when a predetermined fault condition is detected on the signal wires.
  • the fault detection means is generally an over-current trip-out switch which determines a short circuit fault condition when a load current on the signal wires exceeds a predetermined limit.
  • the interrupt means generally a relay, is arranged to operatively interrupt at least one of the signal wires in response to a fault condition being detected by the fault detecting means.
  • the relay has contacts which are normally open, and which are held closed in normal operation to complete the signal path.
  • the relay is driven by a constant current source, which operates in response to the fault detecting means.
  • FIGS 1 through 6 show the arrangements of the system of EP0967833 in more detail.
  • FIG. 1 a 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.
  • 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.
  • transformer TX1 which is a triple wound component
  • the size and construction of the transformer TX1 shown in Figure 5 and used to combine the audio signal with the DC Pilot signal has considerable cost implications and it would be preferable to be able to omit this feature and replace with components which are susceptible of integration.
  • a public address network comprising a driver unit (11) for driving an audio signal (14) on to a pair of signal wires (12) for delivery to one or more audio output units (16), and for driving a pilot signal (15) on to the signal wires (12) for delivery to one or more isolator circuits (20), wherein each isolator circuit (20) is arranged to operatively isolate a section of the signal wires (12) and wherein the network is characterised in that the means for driving the audio signal and the pilot signal onto the signal wires comprises a high pass circuitry part and a low pass circuitry part, the low pass part being arranged to present the pilot signal to the line, whilst the high pass part presents the audio signal to the line, the low pass circuitry part comprising a gyrator circuit.
  • a method of operating a public address network having a series signal path including a pair of signal wires (12) coupled to one or more audio output units (16) and one or more isolators (20) for isolating sections of the signal wires (12), comprising the steps of:
  • FIG. 7 there is shown a combining section of a public address system controller in which a pilot signal and an audio signal may be combined with one another using an LPF and a HPF.
  • the diagram of Figure 7 shows a 2-wire signal line output 12, an inductor L and a capacitor C.
  • the inductor L (having input/output connections X/Y) is a simple LPF which receives the DC Pilot signal 15 at its input end X, whilst an audio signal 14 is a.c. coupled onto the signal lines 12 via capacitor C which is a simple HPF.
  • This simplified circuit shows in basic form how a DC signal part and an AC signal part can be used to provide a combined AC/DC signal output onto the signal wires without the need for a triple wound transformer.
  • the disadvantage of this simplified circuit however is that the size of the inductor L needed to implement such an arrangement is prohibitively large.
  • FIG 8 there is shown in schematic block diagram form a figure similar to the figure 7 implementation which in accordance with the teachings of the present application forms the combining section of a public address system controller in which a pilot signal and an audio signal may be combined with one another.
  • the diagram of Figure 8 (as with figure 7 ) shows a 2-wire signal line output 12, which as in Figures 1 to 6 carries the combined audio signal 14 and a pilot signal 15 - typical values of these two signals being 64V DC for the pilot signal and 100V RMS a.c. for the audio signal - a full wave gyrator circuit G and a capacitor C.
  • the gyrator circuit G (having input/output connections X/Y) receives the DC Pilot signal 15 at its input end X, whilst an audio signal 14 from an audio amplifier such as Audio Amp 114 of figure 5 is a.c. coupled onto the signal lines 12 via capacitor C.
  • a gyrator circuit is, in itself not new and is an established method of replacing a passive inductive component.
  • the particular demands of the isolator circuits for public address system described herein are such that a conventional gyrator circuit may not be directly employed.
  • gyrators are utilised within environments in which there is a relatively high DC signal component relative to the AC component, so that large negative voltage swings do not need to be catered for.
  • the reverse is the case in that a.c. audio signal voltages of 100v rms, around 300v peak-to-peak, need to be catered for along with a relatively smaller DC pilot signal of 64v.
  • an appropriate gyrator circuit that utilises discrete component control circuitry which needs to be unaffected by 300v variation in signal voltage.
  • Figure 9 shows in more detail, the basic design of the two port x/y construction of gyrator G of Figure 8 .
  • the gyrator G comprises two half-cycle gyrators G P and G N - being a positive half-cycle gyrator and a negative half-cycle gyrator respectively - and diodes D P and D N .
  • the diode/gyrator pair D P /G P perform the gyrator function during positive going parts of the line input waveform
  • the diode/gyrator pair D N /G N perform the gyrator function during the negative going parts of the line input.
  • each of the half-cycle gyrators may be broken down into a transimpedance stage, an error comparator stage, a transimpedance stage and a common full-wave integration stage.
  • the positive half-cycle gyrator comprises: positive transimpedance stage Z P , positive transconductance stage gmp, and positive error comparator stage ERR P
  • the negative half-cycle gyrator comprises: negative transimpedance stage Z N , negative transconductance stage gm N , and negative error comparator stage ERR N
  • the negative and positive error comparator stages are commonly connected to a reference input REF1 and a full wave integration stage INT.
  • a transimpedance stage is one which provides an output voltage that is a function of input current
  • a transconductance stage is one that converts an input voltage to a current
  • Node Y is connected to signal line 12 that carries (when present) the 100v rms audio signal and node X is connected to receive the 64v DC pilot signal that is to be combined with it.
  • the circuit of Figure 10 functions by controlling operation of the transconductance stage according to the states of both an output voltage signal ERR and a reference voltage signal Vref.
  • the reference voltage signal rather than being a constant voltage is a variable one that is derived by performing an integration function upon the signal 12 appearing on the signal wires at Y.
  • the transconductance stage is essentially a variable constant current source that provides a constant current output which is a function of its input voltage, and the magnitude of the output constant current is determined by a control signal CNTRL provided to it by the error comparator stage.
  • the transimpedance stage on the other hand is one which will provide an output voltage which is a function of the input current. Together therefore a serially coupled transconductance stage and transimpedance stage will provide a buffered DC voltage to the signal wires at node Y which will vary according to the magnitude of the control signal CNTRL.
  • V ref the voltage V ref will track such changes. In this way, as an ac signal on the wires 12 increases positively, V ref also increases positively.
  • Error Comparator stage ERR P compares the rising reference voltage V ref and the error signal ERR and if the reference voltage is greater than the error signal, then the output signal CNTRL of error Comparator stage ERR P increases to cause the transconductance stage to increase its output current and accordingly to cause a larger DC value output voltage to be produced by the transimpedance stage.
  • a rise at node Y in instantaneous voltage magnitude due to an increasing audio signal voltage causes a rise in the current through the positive side of the gyrator, which is in phase with the rise in voltage across the positive gyrator.
  • control signal CNTRL is arranged to reduce in magnitude, and thereby reduce the current flow in the transconductance stage and accordingly reduce the DC voltage imposed to the line at Y via the transimpedance stage.
  • the reference voltage Vref is a value that is related to the changing voltage on signal wires 12 and has an associated time constant.
  • Vref is such that for signals for which the time constant is less than the period of the ac signal then the reference voltage follows the input waveform, whereas for signals wherein the time constant is much greater than the period, the reference voltage Vref tends towards a constant value.
  • the reference voltage may be assumed to be relatively constant and the DC current level imposed on the signal wires 12 at node Y via the transconductance and transimpedance stage will therefore also tends towards a constant current value and, as the skilled man will realise, the fundamental characteristic of a constant current generator is to exhibit an infinite impedance.
  • the practicalities mean that the impedance of a constant current generator is actually finite - but very high.
  • FIG. 11 there is shown a practical implementation of the block diagram of Figure 10 .
  • the transconductance stages Gm N and Gm P are field effect transistors (FETs) Q1 and Q2 respectively
  • the transimpedance stages Z N and Z P are resistors R1, R2 coupled to the outputs of the FETs
  • the error comparator stages ERR N and ERR P are operational amplifiers U1 and U2 respectively
  • the error signals ERR P and ERR N are taken from the FET outputs
  • the reference voltage V ref is taken from a mid point of an RC chain which acts as an integrator with a corner frequency of approximately 50Hz.
  • the FETs act as variable constant current sources under control of a control signal CNTRL output by the relevant Op-Amp and this control signal varies according to variation of both Vref and the error signal ERR. As the current provided by the FETs is varied, so is the voltage output at node Y.
  • Vref will follow the amplitude of this low frequency AC voltage (with a slight delay), causing the current to ramp up and down virtually in phase with the voltage, the current being limited by Q1 Rds (on) plus R1, in the negative half cycle and by Q2 Rds (on) plus R2 in the positive half cycle, together with the peak negative and peak positive voltage of the low frequency AC voltage.
  • Vref is arranged to become the average of the high frequency signal and as the frequency rises will tend towards a value of zero - resulting in an increase in both Q1 Rds and Q2 Rds as the frequency rises, until the point at which Vref becomes virtually zero and Q1 and Q2 turn off completely presenting a very high impedance across X, Y.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Amplifiers (AREA)
  • Near-Field Transmission Systems (AREA)
  • Selective Calling Equipment (AREA)

Claims (21)

  1. Réseau public d'adresses comprenant une unité pilote (11) pour transmettre un signal audio (14) sur une paire de fils de transmission (12) pour le délivrer à une ou plusieurs unités de sortie audio (16), et pour transmettre un signal pilote (15) sur les fils de transmission (12) pour le délivrer à un ou plusieurs circuits sectionneurs (20), dans lequel chaque circuit sectionneur (20) est aménagé pour isoler en service une section des fils de transmission (12) et dans lequel le réseau est caractérisé en ce que le moyen de transmission du signal audio et du signal pilote sur les fils de transmission comprend une partie de circuits passe-haut et une partie de circuits passe-bas, la partie passe-bas étant aménagée de manière à présenter le signal pilote aux fils de transmission (12), tandis que la partie passe-haut présente le signal audio aux fils de transmission (12), la partie de circuits passe-bas comprenant un circuit gyrateur.
  2. Procédé d'activation d'un réseau public d'adresses ayant un trajet de signal série, comprenant une paire de fils de transmission (12) couplés à une ou plusieurs unités de sortie audio (16) et à un ou plusieurs sectionneurs (20) pour isoler des sections des fils de transmission (12), comprenant les étapes consistant à :
    transmettre un signal audio (14) via les fils de transmission (12) pour délivrance aux unités de sortie audio (16) ;
    transmettre un signal pilote (15) via les fils de transmission (12) pour délivrance aux sectionneurs (20) ;
    détecter le signal pilote à une première extrémité du trajet de signal série en utilisant une extrémité d'un détecteur de ligne (13) ;
    si le signal pilote (15) n'est pas présent à l'extrémité du détecteur de ligne (13), transmettre le signal audio (14) et le signal pilote (15) provenant des deux extrémités du trajet de signal audio, le procédé étant caractérisé en ce que les étapes de transmission du signal audio et du signal pilote via les fils de transmission comprennent, respectivement, l'application du signal audio à une partie de circuits passe-haut et l'application du signal pilote à une partie de circuits passe-bas, la partie passe-bas étant aménagée pour présenter le signal pilote à la ligne, tandis que la partie passe-haut présente le signal audio à la ligne, la partie de circuits passe-bas comprenant un circuit gyrateur.
  3. Réseau selon la revendication 1 ou procédé selon la revendication 2, dans lequel la partie passe-bas et la partie passe-haut partagent un noeud de sortie commun (Y) où le signal audio et le signal pilote sont combinés.
  4. Réseau ou procédé selon la revendication 3, dans lequel le circuit gyrateur comprend une paire de circuits adaptés, dont l'un est un circuit gyrateur positif aménagé pour fonctionner au cours de mi-cycles positifs du signal audio afin d'imposer le signal pilote sur les fils de transmission (12), et l'autre étant un circuit négatif de type gyrateur mis en oeuvre pour fonctionner au cours de mi-cycles négatifs du signal audio afin d'imposer le signal pilote sur les fils de transmission (12).
  5. Réseau ou procédé selon la revendication 4, dans lequel les circuits gyrateurs positif et négatif sont mis en mémoire tampon à partir d'un générateur de signal pilote par des diodes de sectionnement (DP, DN).
  6. Réseau ou procédé selon la revendication 4 ou 5, dans lequel les circuits gyrateurs positif et négatif comprennent chacun un étage de transconductance, un étage de transimpédance et un étage de comparaison d'erreurs, les deux circuits comprenant un noeud commun d'entrée de tension de référence.
  7. Réseau ou procédé selon la revendication 6, dans lequel le noeud de tension de référence est aménagé pour présenter aux circuits positif et négatif une tension de référence, qui est une tension variable qui est dérivée en appliquant une fonction d'intégration lors de l'apparition du signal sur les fils de transmission (12).
  8. Réseau ou procédé selon la revendication 7, dans lequel, dans le cas où aucun signal pilote n'est présent et que le signal audio (14) est présent et symétrique, la tension de référence est nulle.
  9. Réseau ou procédé selon la revendication 7 ou 8, dans lequel, dans le cas où le signal pilote est présent sous la forme d'un décalage CC, la valeur de la tension de référence reflètera celle du décalage CC.
  10. Réseau ou procédé selon la revendication 6, 7, 8 ou 9, dans lequel la tension de référence Vréf est une valeur qui est en rapport avec la tension variable sur les fils de transmission (12) et a une constante de temps associée.
  11. Réseau ou procédé selon la revendication 10, dans lequel Vréf est tel que, pour des signaux pour lesquels la constante de temps est inférieure à la période du signal audio, la tension de référence suit la forme d'onde d'entrée, tandis que, pour des signaux dans lesquels la constante de temps est largement supérieure à la période, la tension de référence Vréf tend vers une valeur constante.
  12. Réseau ou procédé selon la revendication 10 ou 11, dans lequel, pour un signal audio de haute fréquence, la tension de référence est relativement constante et le niveau de courant CC imposé sur les fils de transmission (12) via l'étage de transconductance et l'étage de transimpédance tendra vers une valeur de courant constante.
  13. Réseau ou procédé selon l'une quelconque des revendications 6 à 12, dans lequel l'étage de transconductance comprend une source de courant constante variable qui fournit une sortie de courant constante qui est fonction de sa tension d'entrée.
  14. Réseau ou procédé selon la revendication 13, dans lequel l'amplitude du courant de sortie constant de l'étage de transconductance est déterminée par un signal de commande CNTRL qui lui est délivré par l'étage de comparaison d'erreurs.
  15. Réseau ou procédé selon la revendication 14, dans lequel l'étage de transimpédance fournit une tension de sortie qui est fonction du courant d'entrée qui lui est fourni par l'étage de transconductance pour fournir aux fils de transmission (12) une tension CC mise en mémoire tampon, qui variera selon la grandeur du signal de commande CNTRL.
  16. Réseau ou procédé selon la revendication 15, dans lequel, pour un signal CA à variation lente, la tension Vref suit ces variations de sorte que, lorsque le signal CA sur les fils de transmission (12) augmente de manière positive, Vref augmente de manière positive.
  17. Réseau ou procédé selon l'une quelconque des revendications 6 à 16, dans lequel l'étage de comparaison d'erreurs compare la tension de référence Vréf et le signal d'erreur ERR et, si la tension de référence est supérieure au signal d'erreur, le signal de sortie CNTRL de l'étage de comparaison d'erreurs augmente pour amener l'étage de transconductance à augmenter son courant de sortie et, par suite, entraîner la production d'une plus grande tension de sortie de valeur CC par l'étage de transimpédance.
  18. Réseau ou procédé selon l'une quelconque des revendications 6 à 17, dans lequel l'étage de comparaison d'erreurs compare la tension de référence Vréf et le signal d'erreur (ERR) et, si la tension de référence est inférieure au signal d'erreur, le signal de commande CNTRL est adapté pour réduire sa grandeur et, par suite, réduire le flux de courant dans l'étage de transconductance et, en conséquence, réduire la tension CC imposée sur les fils de transmission (12) via l'étage de transimpédance.
  19. Réseau ou procédé selon l'une quelconque des revendications 6 à 18, dans lequel les étages de transconductance comprennent des transistors à effet de champ (FET), les étages de transimpédance comprennent des résistances couplées aux sorties des FET et les étages de comparaison d'erreurs comprennent des amplificateurs opérationnels.
  20. Réseau ou procédé selon la revendication 19, dans lequel les signaux d'erreurs ERRP et ERRN sont prélevés des sorties des FET.
  21. Réseau ou procédé selon la revendication 20, dans lequel la tension de référence Vréf est prélevée d'un point intermédiaire d'une chaîne RC qui agit comme intégrateur avec une fréquence de coin d'environ 50 Hz.
EP06255349A 2005-10-20 2006-10-17 Améliorations apportées à un système d'annonce en public avec circuits isolateurs de zone Not-in-force EP1777988B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0521337A GB2432091B (en) 2005-10-20 2005-10-20 Improvements to a public address system having zone isolator circuits

Publications (3)

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EP1777988A2 EP1777988A2 (fr) 2007-04-25
EP1777988A3 EP1777988A3 (fr) 2008-05-28
EP1777988B1 true EP1777988B1 (fr) 2009-08-12

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP06255349A Not-in-force EP1777988B1 (fr) 2005-10-20 2006-10-17 Améliorations apportées à un système d'annonce en public avec circuits isolateurs de zone

Country Status (4)

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EP (1) EP1777988B1 (fr)
AT (1) ATE439744T1 (fr)
DE (1) DE602006008402D1 (fr)
GB (1) GB2432091B (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3731539A4 (fr) * 2017-12-22 2021-08-04 Toa Corporation Système de diffusion
EP4134954B1 (fr) * 2021-08-09 2023-08-02 OPTImic GmbH Procédé et dispositif d'amélioration du signal audio

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB523057A (en) * 1938-11-24 1940-07-04 Guided Radio Corp Improvements in telephone and like electric signalling systems
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
GB9813882D0 (en) * 1998-06-27 1998-08-26 Protec Fire Detection Plc Public address system having zone isolator circuits
US20040184598A1 (en) * 2001-10-30 2004-09-23 Integration Associates Inc. Method and apparatus for isolation in a Caller ID or call monitor interface circuit

Also Published As

Publication number Publication date
ATE439744T1 (de) 2009-08-15
GB0521337D0 (en) 2005-11-30
EP1777988A3 (fr) 2008-05-28
DE602006008402D1 (de) 2009-09-24
GB2432091B (en) 2009-06-17
EP1777988A2 (fr) 2007-04-25
GB2432091A (en) 2007-05-09

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