Method and apparatus for reporting dangerous conditions

• US 4,551,710 A
• Filed: 04/19/1984
• Issued: 11/05/1985
• Est. Priority Date: 04/29/1983
• Status: Expired due to Fees

• Current Assignee: Cerberus AG Ch-8708 Mannedorf Switzerland
• Original Assignee: Cerberus ABP Investor LLC (Cerberus Capital Management LP)
• Inventors: Guttinger, Hannes, Pfister, Gustav, Troup, Alan P.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/602,127
• Time in Patent Office: 565 Days
• Field of Search: 340/505, 340/500, 340/506, 340/518, 340/825.52, 340/825.54, 340/825.07-825.13, 343/6.5 R, 343/6.5 LC, 343/6.5 SS, 343/6.8 LC
• US Class Current: 340/505
• CPC Class Codes: G08B 26/004 with common interrogation of substations
• CPC Class Codes: G08B 29/16 Security signalling or alarm systems, e.g. redundant systems
• CPC Class Codes: G08B 29/181 due to failing power supply

Abstract

In an alarm system a central signal station periodically transmits interrogation signals, preferably in the form of infrared radiation packets to remotely located detectors which transmit a response signal back to the central signal station after differing time delays that are characteristic for the individual detectors and which permit the localization of the source of the response signal. In an alarm state, the detectors respond to every interrogation signal, in the normal operational state to only every m^th interrogation signal, i.e. less often, and in a state of diminishing battery potential to only every small p^th interrogation signal, i.e. even less often. The state of the individual detectors is determined from the frequency with which the response signals are transmitted back by the detectors, that is the ratio of the response signals to the interrogation signals.

Claims

1. A method of signal transmission and signal processing in an alarm system comprising a central signal station and remotely located detectors, comprising the steps of:

transmitting an interrogation signal to said detectors from said central signal station;

transmitting response signals from said detectors after a time delay characteristic of each individual detector back to the central signal station after receiving said interrogation signal;

said response signals corresponding to a current state of the individual detector;

receiving and evaluating the response signals at the central signal station;

the detectors transmitting the response signals after every n^th interrogation signal when in an alarm state; and

the detectors transmitting response signals only after every m^th interrogation signal when in an operationally ready state and the alarm state is absent;

wherein;

m and n are integers; and

m is greater than n.

2. The method as defined in claim 1, wherein:

said detectors transmit said response signals only after every p^th interrogation signal when in an operationally impaired state;

wherein;

p is an integer greater than m.

3. The method as defined in claim 1, wherein:

n=1 and said detectors transmit said response signals after every interrogation signal when in an alarm state.

4. The method as defined in claim 1, wherein:

said interrogation signals and said response signals comprise packets of pulses of a predetermined frequency and duration.

5. The method as defined in claim 4, wherein:

said predetermined frequency of said pulses of said packets of said response signals depends upon a measurement value characteristic of a condition to be detected.

6. The method as defined in claim 4, wherein:

said predetermined duration of said pulses of said packets of said response signals depends upon a measurement value characteristic of a condition to be detected.

7. The method as defined in claim 1, wherein:

said central signal station evaluates the response signals received such that after the transmission of q-interrogation signals and the reception of at least x-response signals from a given detector within the duration of the q-interrogation signals an alarm signal is given and such that after the transmission of q-interrogation signals and the reception of at least y but less than x-response signals from a given detector within the duration of the q-interrogation signals an operationally ready signal is given;

wherein;

q, x and y are integers; and

x is greater than y.

8. The method as defined in claim 1, wherein:

said central signal station transmits said interrogation signals to said detectors and the detectors transmit said response signals back to the central signal station by wireless communication means.

9. The method as defined in claim 8, wherein:

said wireless communication means comprises infrared radiation.

10. The method as defined in claim 9, wherein:

said wireless communication means comprises infrared radiation focused by optical focusing means.

11. A device for reporting danger or other desired conditions comprising:

a central signal station;

detectors remotely located from said central signal station;

said central signal station including at least one signal transmitter for transmitting interrogation signals;

each of said detectors comprising;

a signal receiver for receiving said interrogation signals;

a signal transmitter for transmitting response signals;

a sensor for influencing said response signals;

delay means for temporally delaying the transmission of the response signals in relation to the reception of a interrogation signal by different delay times characteristic of each individual detector;

said central signal station further including;

a signal receiver for receiving the response signals transmitted by the individual detectors;

said detectors being constructed for transmitting a response signal after every n^th interrogation signal received when in an alarm state and after every m^th interrogation signal received when in an operationally ready state and the alarm state is absent; and

the central signal station further including an evaluation device for generating an alarm signal after the transmission of q-interrogation signals and the reception of at least x-response signals from a given detector within the duration of the q-interrogation signals and for generating an operational readiness signal after the transmission of q interrogation signals and the reception of at least y but less than x-response signals within the duration of the q-interrogation signals;

wherein;

m, n, q, x and y are predetermined integers;

m is greater than n;

x is greater than y;

q is at least equal to x; and

y is at least equal to 1.