Radio central station alarm system
First Claim
1. In a radio central station alarm system including a central station and a plurality of remote stations for transmitting alarm signals to the central station by means of radio signals encoding binary data words, each of sid remote stations including a plurality of alarm sensors for detecting the occurrence of a respective one of a plurality of alarm conditions at the remote station, each of said data words including a first plurality of bits identifying the remote station originating it, a second plurality of bits identifying an alarm condition occurring at that remote station, and a frame pulse, remote station apparatus comprising:
- alarm sensor sequencing means responsive to any of said alarm sensors indicating the occurrence of an alarm condition for cyclically selecting each of said alarm sensors in turn and for producing a plurality of binary coded output signals identifying the selected alarm sensor;
data storage means for storing a plurality of bits identifying said remote station;
a first clock for producing an output signal having timing pulses at predetermined regular intervals;
gate means responsive to the output signal of said first clock for passing said timing pulses when enabled and for inhibiting said timing pulses when not enabled;
a first counter for counting the timing pulses produced by said first clock which are not passed by said gate means;
data sequencing means for cyclically selecting each of the bits stored by said data storage means and each of the binary signals produced by said alarm sensor sequencing means in turn and for producing a frame pulse initiating output signal intermediate the selection of a predetermined two of said bits and binary signals, said data sequencing means advancing in response to each timing pulse passed by said gate means;
gate control means responsive to said data sequencing means and to said first counter for enabling said gate means when the bit or binary signal selected by said data sequencing means has a first binary value, for inhibiting said gate means until one timing pulse is counted by said first counter when the bit or binary signal selected by said data sequencing means has a second binary value, and for inhibiting said gate means until two timing pulses are counted by said first counter when a frame pulse initiating output signal is being produced; and
radio transmitter means responsive to said alarm sensor sequencing means for transmitting a radio output signal representative of the output signal of said gate means when said alarm sensor sequencing means selects an alarm sensor indicating the occurrence of an alarm condition.
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Accused Products
Abstract
A radio central station alarm system including a central station and a plurality of remote stations for transmitting alarm signals to the central station by means of radio signals. Alarm signals are transmitted repeatedly in a sequence which reduces the probability that signals transmitted by one remote station will be completely obscured by signals transmitted by other remote stations. A pulse position modulation binary data format is used which simplifies both remote and central station apparatus and facilitates error-free data transmission. The central station is highly immune to noise and performs a number of tests on received data signals to reduce or eliminate false or erroneous alarm indications. Latching alarm sensor circuits are provided for use at the remote stations to insure that all transmission sequences are completed. Protective circuits are provided for disabling any remote station which transmits signals for longer than a maximum allowable transmission interval.
41 Citations
15 Claims
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1. In a radio central station alarm system including a central station and a plurality of remote stations for transmitting alarm signals to the central station by means of radio signals encoding binary data words, each of sid remote stations including a plurality of alarm sensors for detecting the occurrence of a respective one of a plurality of alarm conditions at the remote station, each of said data words including a first plurality of bits identifying the remote station originating it, a second plurality of bits identifying an alarm condition occurring at that remote station, and a frame pulse, remote station apparatus comprising:
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alarm sensor sequencing means responsive to any of said alarm sensors indicating the occurrence of an alarm condition for cyclically selecting each of said alarm sensors in turn and for producing a plurality of binary coded output signals identifying the selected alarm sensor; data storage means for storing a plurality of bits identifying said remote station; a first clock for producing an output signal having timing pulses at predetermined regular intervals; gate means responsive to the output signal of said first clock for passing said timing pulses when enabled and for inhibiting said timing pulses when not enabled; a first counter for counting the timing pulses produced by said first clock which are not passed by said gate means; data sequencing means for cyclically selecting each of the bits stored by said data storage means and each of the binary signals produced by said alarm sensor sequencing means in turn and for producing a frame pulse initiating output signal intermediate the selection of a predetermined two of said bits and binary signals, said data sequencing means advancing in response to each timing pulse passed by said gate means; gate control means responsive to said data sequencing means and to said first counter for enabling said gate means when the bit or binary signal selected by said data sequencing means has a first binary value, for inhibiting said gate means until one timing pulse is counted by said first counter when the bit or binary signal selected by said data sequencing means has a second binary value, and for inhibiting said gate means until two timing pulses are counted by said first counter when a frame pulse initiating output signal is being produced; and radio transmitter means responsive to said alarm sensor sequencing means for transmitting a radio output signal representative of the output signal of said gate means when said alarm sensor sequencing means selects an alarm sensor indicating the occurrence of an alarm condition. - View Dependent Claims (2, 3, 4, 5)
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6. A central station for use in a radio central station alarm system for receiving alarm signals from a plurality of remote stations by means of radio signals encoding repetitive binary data words, each of said data words including a predetermined number of bits of information each including a timing signal, a bit having a first binary value being represented by a timing signal occurring a first predetermined time interval after the preceding timing signal and a bit having a second binary value being represented by a timing signal occurring a second longer time interval after the preceding timing signal, said data words being separated from one another by a frame pulse represented by a timing signal occurring a third still longer time interval after the preceding timing signal, comprising:
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radio receiver means for receiving said radio signals and for producing a first data output signal including timing pulses corresponding to the timing signals in the received radio signals; a shift register having a plurality of output terminals for applying an output signal to successive output terminals as said shift register is shifted; means for shifting said shift register at a predetermined rate; first means responsive to the occurrence of a timing pulse in said first data signal for producing a second data output signal having a first binary value if said shift register is applying an output signal to a first output terminal when said timing pulse occurs and having a second binary value if said shift register is applying an output signal to a second output terminal when said timing pulse occurs and for subsequently presetting said shift register; means for storing said second data output signal as one of the successive bits in a data word being received; means for counting the timing pulses in said first data output signal; second means responsive to the occurrence of a timing pulse in said first data output signal for producing an output signal indicating that a frame pulse has been received if said shift register is applying an output signal to a third output terminal when said timing pulse occurs and for subsequently presetting said shift register; means responsive to the output signal of said second means for producing a control transfer output signal if the number of pulses registered by said means for counting equals said predetermined number and for subsequently resetting said means for counting; and means responsive to said control transfer output signal for producing an alarm output indication corresponding to the data word stored in said means for storing. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A radio central station alarm system including a central station and a plurality of remote stations for transmitting alarm signals to the central station by means of radio signals encoding repetitive data words, each of said remote stations including a plurality of alarm sensors for detecting the occurrence of a respective one of a plurality of alarm conditions at the remote station, each of said data words including a first plurality of bits identifying the remote station originating it, a second plurality of bits identifying an alarm condition occurring at that remote station, and a frame pulse, each of said bits and frame pulses including a timing pulse, a bit having a first binary value being represented by a timing signal occurring a first predetermined time interval after the preceding timing signal, a bit having a second binary value being represented by a timing signal occurring a second longer time interval after the preceding timing signal, and a frame pulse being represented by a timing signal occurring a third still longer time interval after the preceding timing signal, comprising:
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remote station apparatus including; alarm sensor sequencing means responsive to any of said alarm sensors indicating the occurrence of an alarm condition for cyclically selecting each of said alarm sensors in turn and for producing a plurality of binary coded output signals identifying the selected alarm sensor; data storage means for storing a plurality of bits identifying said remote station; a first clock for producing timing signals at predetermined regular intervals; gate means responsive to the output signal of said first clock for passing said timing signals when enabled and for inhibiting said timing signals when not enabled; a first counter for counting the timing signals produced by sid first clock which are not passed by said gate means; data sequencing means for cyclically selecting each of the bits stored by said data storage means and each of the binary signals produced by said alarm sensor sequencing means in turn and for producing a frame pulse initiating output signal intermediate the selection of a predetermined two of said bits and binary signals, said data sequencing means advancing in response to each timing signal passed by said gate means; gate control means responsive to said data sequencing means and to said first counter for enabling said gate means when the bit or binary signal selected by said data sequencing means has a first binary value, for inhibiting said gate means until one timing signal is counted by said first counter when the bit or binary signal selected by said data sequencing means has a second binary value, and for inhibiting said gate means until two timing signals are counted by said first counter when a frame pulse initiating output signal is being produced; and radio transmitter means responsive to said alarm sensor sequencing means for transmitting a radio output signal representative of the output signal of said gate means when said alarm sensor sequencing means selects an alarm sensor indicating the occurrence of an alarm condition; and central station apparatus including; radio receiver means for receiving said radio output signal and for producing a first data output signal including timing pulses corresponding to the timing signals in the received radio signal; a shift register having a plurality of output terminals for applying an output signal to successive output terminals as said shift register is shifted; means for shifting said shift register at a predetermined rate; first means responsive to the occurrence of a timing pulse in said first data signal for producing a second data output signal having a first binary value if said shift register is applying an output signal to a first output terminal when said timing pulse occurs and having a second binary value if said shift register is applying an output signal to a second output terminal when said timing pulse occurs and for subsequently presetting said shift register; means for storing said second data output signal as one of the successive bits in a data word being received; means for counting the timing pulses in said first data output signal; second means responsive to the occurrence of a timing pulse in said first data output signal for producing an output signal indicating that a frame pulse has been received if said shift register is applying an output signal to a third output terminal when said timing pulse occurs and for subsequently presetting said shift register; means responsive to the output signal of said second means for producing a control transfer output signal if the number of pulses registered by said means for counting equals said predetermined number and for subsequently resetting said means for counting; and means responsive to said control transfer output signal for producing an alarm output indication corresponding to the data word stored in said means for storing.
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Specification