Smoke and fire detection system communication
First Claim
1. A fire detection system of the kind in which a controller sends data to a plurality of transponders via a communication line in the form of a series of pulses, said system comprising:
- driver circuitry means associated with said controller for forming a sequence of spaced-apart pulses on said line with each said pulse having a value represented by a selected signal amplitude value on said line including means for spacing each formed pulse apart from each adjacent formed pulse with a selected spacing signal amplitude value on said line different from each said selected signal amplitude value associated with each said pulse value,decoder circuitry means associated with each said transponder for detecting each said spaced-apart pulse on said line and for decoding each said spaced-apart pulse based solely on its amplitude value,including means for decoding said pulses without regard to the particular time when each said pulse begins or to its duration, andmeans, associated with each transponder, for returning data to said controller in the form of data signals, each said data signal having a duration based on the data to be returned.
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Accused Products
Abstract
A smoke and fire detection system wherein a central controller transmits data to remote transponders on a voltage supply line by pulse code modulation (PCM) of the supply voltage, and the transponders communicate with the controller by pulse width modulated (PWM) current pulses over the voltage supply line. A transmitter in the controller supplys a nominal operating voltage to the transponders and transmits a data word comprising a plurality of data bits to the transponders over the line. The transmitter generates each data bit by switching the voltage supplied to the line from the nominal operating voltage to a first voltage corresponding to a first logical level or a second voltage corresponding to a second logical level. A decoder in each transponder derives the transmitted data word. The decoder detects each data bit by detecting the transition from the nominal voltage to the first or second voltages, and the decoder determines the logical level of each bit by measuring the transmitted voltage level immediately after detecting the transition. The transponder returns data to the controller in the form of data signals, each data signal having a duration based on the data to be returned. With such arrangement, the transponders do not require a clock or other timing circuitry to communicate with the controller. Also, the controller may vary the data rate or bit duration without interfering with the operation of the transponders.
241 Citations
17 Claims
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1. A fire detection system of the kind in which a controller sends data to a plurality of transponders via a communication line in the form of a series of pulses, said system comprising:
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driver circuitry means associated with said controller for forming a sequence of spaced-apart pulses on said line with each said pulse having a value represented by a selected signal amplitude value on said line including means for spacing each formed pulse apart from each adjacent formed pulse with a selected spacing signal amplitude value on said line different from each said selected signal amplitude value associated with each said pulse value, decoder circuitry means associated with each said transponder for detecting each said spaced-apart pulse on said line and for decoding each said spaced-apart pulse based solely on its amplitude value, including means for decoding said pulses without regard to the particular time when each said pulse begins or to its duration, and means, associated with each transponder, for returning data to said controller in the form of data signals, each said data signal having a duration based on the data to be returned. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fire detection system of the kind in which a plurality of transponders is coupled to a controller by a communication line and each sends data to the controller via the communication line, the system comprising:
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transmission circuitry associated with each transponder for sending said data via the communication line in the form of a group of data signals, each said data signal having a duration based on data presented at the input of said transmission circuitry, reference circuitry for presenting at the input of said transmission circuitry a reference value intended to provide a reference signal of a predetermined nominal duration at the controller, every said group of data signals being accompanied by a current said reference signal, circuitry associated with said controller for detecting the actual durations of said data signals and the actual duration of the associated said reference signal and calibration means for comparing a representation of said reference signal to other members of said group of data signals. - View Dependent Claims (10, 11, 12, 13)
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9. A fire detection system of the kind in which a controller randomly sends outgoing data in the form of one-valued bits and zero-valued bits to a plurality of transponders via a communication line and said transponders return data to said controller via said communication line, said system comprising:
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circuitry associated with said controller including means for sending said outgoing data in the form of a succession of transponder identifying 13-bit words, each one-valued bit being represented by a first voltage level on said communication line, each zero-valued bit being represented by a second voltage level on said communication line, said 13-bit word including a nine-bit address, a 3-bit command word, and a parity bit, said circuitry including means for generating spacing signals between each one-valued bit or each zero-valued bit with each spacing signal represented by a third voltage level on said communication line and circuitry associated with each said transponder for returning data to said controller, following the receipt of each said 13-bit word, said data being returned in the form of a selected plurality of pulses, each represented by the drawing of current from said communication line for a period having a duration representative of a corresponding data value at a substantially constant line voltage.
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14. A communication method for a fire detection system of the kind in which a controller sends data to a plurality of transponders via a communication line in the form of a series of pulses, said method comprising
forming spaced-apart pulses on said line, the amplitudes of said pulses representing said data in accordance with a pulse code and including forming spacing signals between adjacent pulses with the spacing signals having an amplitude different from the spaced-apart pulses, detecting the start of each said pulse on said line and decoding each said pulse based solely on its amplitude level, decoding said pulses without regard to the particular time when each said pulse begins or its duration, and returning data to said controller in the form of data signals, each said data signal having a duration based on the data to be returned.
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15. A communication method for a calibratable fire detection system of the kind in which a plurality of transponders each sends data, via respective transmission circuitry, to a controller via a communication line, the method comprising:
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sending said data in the form of a group of data signals, each said data signal having a duration based on data presented to the respective transmission circuitry, presented to the respective transmission circuitry a reference value, intended to provide a reference signal, of a predetermined nominal duration at the controller, every said group of data signals being accompanied by a current said reference signal, and detecting the durations of said data signals and the duration of the associated said reference signal for use in calibration.
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16. A communication method for use in a fire detection system of the kind in which a controller sends data, in the form of one-valued bits and zero-valued bits, to a plurality of transponders via a communication line and said transponders return data to said controller via said communication line, said method comprising:
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sending said data in the form of a succession of 13-bit words, each one-valued bit being represented by a first voltage level on said communication line, each zero-valued bit being represented by a second voltage level on said communication line, said 13-bit word including a nine-bit address, a 3-bit command word, and a parity bit, including spacing each bit from each adjacent bit by a spacing signal represented by a third voltage level different from said first and said second voltage levels and returning data to said controller, following the receipt of each said 13-bit word, said data being returned in the form of five pulses, each represented by the drawing of current from said communication line for a period having a duration representative of a corresponding data value.
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17. A fire detection system of the kind in which a controller randomly sends outgoing data in the form of one-valued bits and zero-valued bits to a plurality of transponders via a communication line and said transponders return data to said controller via said communication line, said system comprising:
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means, associated with said controller, for sending said outgoing data in the form of a succession of transponder identifying words f a predetermined number of bits, each one-valued bit being represented by a first voltage level on said communication line, each zero-valued bit being represented by a second voltage level on said communication line, each said word including at least an address portion, and a command portion, said sending means including means for generating spacing signals between each one-valued bit or each zero-valued bit with each spacing signal represented by a third voltage level on said communication line and means, associated with each said transponder, for returning data to said controller, following the receipt of each said word, said data being returned in the form of a selected plurality of pulses, each represented by the drawing of current from said communication line for a period having a duration representative of a corresponding data value at a substantially constant line voltage.
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Specification