US 4,067,008 A · Multiplex interrogation system using pulses

Abstract

This interrogation system monitors the status of a plurality of protection zone transducers by repeatedly supplying a series of sequential interrogation pulses thereto sufficient to address and scan every transducer associated with a protection zone. Reply pulses are received from a transponder associated with a protection zone transducer and the reply pulses received over a selected number of prior sequential scans form a response pattern from which the condition of each transducer and its protection zone is determined. At least three conditions may be determined from the reply response pattern, including an alarm condition, a normal condition, and an out-of-service condition. Information relative to each transducer and its respective protection zone is stored in the form of bits at memory addresses corresponding to the count of the protection zone transducer from which that information is received. Provision is made for synchronizing the transducers associated with the respective protection zones to the count of interrogation pulses delivered thereto to thereby maintain accurate correlation and integrity between the protection zones addressed and the reply pulses received. The interrogation and reply pulses are preferably direct voltage pulses and the system is compatible for use with connection to a standard telephone line system. Information in the form of a visual indication and printed record may be provided relative to the status, function and number of a selected transponder and the condition of its protection zone.

Claims15

Dependent claims

In an interrogation and response system for monitoring the status of a plurality of protection zones of the type in which the protection zones are interrogated in sequence repeatedly by a series of interrogation signals, each sequential interrogation of all the protection zones constituting a complete sequential scan thereof, and reply signals are sequentially supplied according to the status of each protection zone in response to the respective sequential interrogation signals, the improvement comprising:

means for receiving said reply signals and generating for each of the protection zones a pattern of said reply signals for at least four of the most recent ones of said complete sequential scans of said zones;
and means responsive to said reply signal patterns for determining and indicating therefrom the status of each particular protection zone, said zone status determining and indicating means indicating a change in status of one of said zones only when the entire pattern of the associated one of said reply signal patterns indicates a change in status whereby to substantially eliminate the effect of spurious signals on said system.

Apparatus for monitoring the status of a plurality of zones, each of said zones having a different numerical assignment between the numbers 1 and n, said apparatus comprising:

a plurality of transponder means equal in number to the number of said zones, each of said transponder means being associated with one of said zones and being operable to count interrogation signals received, each of said transponder means being operable in response to a reset signal to set its count to 0 and being operable upon counting a number of interrogation signals equal to the numerical assignment of the one of said zones with which it is associated to generate a reply signal corresponding to the status of said associated one of said zones;
means for repeatedly generating a series of n number of said interrogation signals followed by said reset signal and transmitting same to said transponder means whereby each said series of interrogation signals followed by said reset signal constitutes a complete sequential scan of said zones, said interrogation signal generating means being operable during the generation of each of said series of interrogation signals to generate after a selected number of said interrogation signals less than n have been generated a count set signal and to transmit same to said transponder means, each of said transponder means being operable in response to said count set signal to set its count to said selected number whereby to reduce any effect of spurious signals on said apparatus;
means for receiving said reply signal from said transponder means and generating for each of said zones a pattern of said reply signals for a plurality of the most recent ones of said complete sequential scans of said zones, said reply signal patterns being generated from at least four of said complete sequential scans of said zones;
electrical conductor means for transmitting DC pulses interconnecting said transponder means, interrogation signal generating means and reply signal receiving means;
said interrogation, reset, reply and count set signals all being DC pulses;
means responsive to said reply signal patterns for generating for each of said zones a condition signal indicative of the status thereof, said condition signal generating means being operable to generate a condition signal indicating a different status only when the entire pattern of the associated one of said reply signal patterns indicates a change in status whereby to substantially eliminate the effect of spurious signals on said apparatus.

3 more elements

Dependencies are inferred from the claim text.

Multiplex interrogation system using pulses

Life of this patent

Multiplex interrogation system using pulses

Life of this patent

Abstract

Claims15