High security alarm transmission system
First Claim
1. In a security system including a transmission line for permitting the transmission of information between a secured area and a monitoring area, monitoring means at said secured area including code means operable to continuously provide a line security code comprised of a sequence of code bits, data means for providing at least one data bit representing information to be transmitted to said monitoring area, and select means for receiving the bits of said line security code and said data bit, and means for controlling said select means to provide a modified line security code, including selected code bits of said line security code and said data bit, which is continuously transmitted over said transmission line to said monitoring area, and receiver means at said monitoring area including means for receiving said modified line security code, first means responsive to said selected code bits of the line security code to provide a first output indicative of the security of the transmission line, and second means responsive to said data bit to provide a second output representing said information.
1 Assignment
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Accused Products
Abstract
An alarm transmission system for transmitting alarm and status information from a secured area to a monitoring area over a transmission line includes a code source in the secured area which provides a line security code for securing the transmission line, an alarm source which modifies the line security code in the event of an alarm condition, and a data selection network which enables preselected bits of the line security code and a further bit representing the access/secure status of the secured area to be transmitted to the monitoring area during preassigned time slots for comparison at the monitoring area with corresponding bits of a reference code provided by a reference code source, and an access/source status bit to permit an alarm to be indicted when one or more of the compared bits differ. In one embodiment, the code sources comprise code generators at the secured and monitoring areas which include a working code generator which produces the code, a reset code generator operable upon command to load a random code word into the working generator and a preset code circuit operable upon command to load a preset code word into the reset generator, the commands being provided by a command generator at the monitoring area. In a second embodiment, line security code words and alarm code words are stored at the secured and monitoring areas, the line security code words being read out periodically and compared at the monitoring area to secure the transmission line, and the alarm words being read out and compared to indicate an alarm condition.
21 Citations
43 Claims
- 1. In a security system including a transmission line for permitting the transmission of information between a secured area and a monitoring area, monitoring means at said secured area including code means operable to continuously provide a line security code comprised of a sequence of code bits, data means for providing at least one data bit representing information to be transmitted to said monitoring area, and select means for receiving the bits of said line security code and said data bit, and means for controlling said select means to provide a modified line security code, including selected code bits of said line security code and said data bit, which is continuously transmitted over said transmission line to said monitoring area, and receiver means at said monitoring area including means for receiving said modified line security code, first means responsive to said selected code bits of the line security code to provide a first output indicative of the security of the transmission line, and second means responsive to said data bit to provide a second output representing said information.
- 3. In a security system including a transmission line for permitting the transmission of information between a secured area and a monitoring area, monitoring means at said secured area including code means operable to continuously provide a line security code comprised of a sequence of code bits, data means for providing at least one data bit representing information to be transmitted to said monitoring area, and select means for receiving the bits of said line security code and said data bit, and means for controlling said select means to provide a modified line security code, including selected code bits of said line security code and said data bit, for transmission over said transmission line to said monitoring area, and receiver means at said monitoring area including means for receiving said modified line security code, first means having further code means operable to continuously provide a reference code comprised of a sequence of code bits which is identical to said line security code, and comparator means for comparing the selected code bits of the line security code with corresponding bits of the reference code and operable to provide a first output whenever the compared bits are different, second means responsive to said data bit to provide a second output representing said information, and synchronizing means normally operable in a first mode for providing a signal for synchronizing the operation of said further code means with said code means at said secured area.
- 13. In a security system including a transmission line for permitting information to be transmitted between a protected area and a monitoring area, monitoring means at said protected area including alarm source means operable in access and secure modes, status means for providing a status bit indicating the operating mode for said alarm source means, first code generating means operable to provide a first sequence of code bits, select means for receiving the bits of said first sequence and said status bit and for transmitting preselected code bits of said first sequence and said status bit over said transmission line to said monitoring area, and receiver means at said monitoring area including second code generating means for generating a second sequence of code bits which is identical to the first sequence of code bits, further status means for providing a reference status bit indicating a desired operating mode for said alarm source means, first comparator means for comparing the code bits of the first sequence with corresponding bits of the second sequence, and second comparator means for comparing the status bit with the reference status bit, and alarm means controlled by said comparator means for providing an alarm indication whenever one of the compared bits are different.
- 26. In a security system including a transmission line extending between a secured area and a monitoring area, apparatus for securing the transmission line and for enabling the transmission of information between said monitoring and secured areas, said apparatus comprising a first working code generating means at said secured area normally operable to provide a line security code comprised of a known, pseudo-random sequence of code bits for transmission over said transmission line to the monitoring area, a first reset code generating means operable to provide a pseudo-random code word, and first control means operable upon command to transfer the code word provided by said first reset code generating means to said first working code generator, a second working code generating means at said monitoring area operable in synchronism with said first working code generating means to generate a reference code with is identical with said line security code for comparison with the line security code sequence transmitted from the secured area to permit an alarm indication to be provided whenever the code sequences are different, a second reset code generating means operating in synchronism with said first reset code generating means to provide a code word which is identical to the code word provided by said first reset code generating means and second control means operable upon command to transfer the code word provided by said second reset code generating means to said second working code generating means, and command generator means at said monitoring area normally operable to provide a first command signal for synchronizing the operation of said first and second working code generating means and controllable to provide a second command signal for effecting the transfer of the code words provided by said first and second reset code generating means to said first and second working code generating means, respectively.
- 31. In a security system including a transmission line extending between a secured area and a monitoring area, apparatus for securing the transmission line and for enabling the transmission of information between said monitoring and secured areas, said apparatus comprising a first code means at said secured area including a first code source for providing a first code word and a second code source for providing a second code word, and control means for normally enabling the code word provided by said first code source to be transmitted over said transmission line to said monitoring area, second code means at said monitoring area including a third code source for providing a code word which is identical to the code word provided by said first code source, a fourth code source for providing a code word which is identical to the code word provided by said second code source, comparator means for receiving the code word transmitted for said secured area, and second control means for normally enabling the code word provided by said third code source to be extended to said comparator means, said comparator means being operable to compare the code word received from said secured area with the code word provided by said third code source and to provide an output whenever the code words are different, said first control means being enabled upon command to transmit the code word provided by said second code word source over said transmission line to said monitoring area and said second control means being operable upon command to extend the code word provided by said fourth code source to said comparator means for comparison with the code word received from said secured area.
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36. In a security system including a transmission line for permitting the transmission of information between a secured area and a monitoring area, monitoring means at said secured area including first code source means for providing at least first and second sequences of different code words and select means for normally enabling the transmission of said first sequence of code words over said transmission line to said monitoring area, receiver means at said monitoring area including second code source means for normally providing third and fourth sequences of code words which are identical with said first and second sequences of code words, respectively, control means for normally enabling the comparison of the code words of said first and third sequences and for providing an indication whenever the code words compared are different, and alarm means at said secured area for controlling said select means to enable the code words of said second sequence to be transmitted to said monitoring area for indicating an alarm condition, said control means being operable when code words of said second code sequence are transmitted to said monitoring area to effect the comparison of the code words of the fourth sequence with the code words of the second sequence and for providing a further indication whenever the code words compared are the same.
- 37. In a security system including a transmission line to permit the transmission of alarm information between a secured area and a monitoring area, monitoring means at said secured area including a first code storage means storing a plurality of line security code words in a predetermined sequence, and enabling means interposed between the output of said first code storage means and said transmission line for normally enabling said code words to be transmitted to said monitoring area over said transmission line, and receiver means at said monitoring area including second code storage means storing a plurality of reference code words which are identical with the code words stored by said first code storage means, sequencing means for providing sequencing signals for transmission to said secured area for controlling said first code storage means to effect the readout of said line security code words for transmission to said monitoring area, said second code storage means being responsive to said sequencing signals to provide said reference code words in synchronism with the readout of the line security code words at said secured area, code word comparator means for comparing the line security code words transmitted from said secured area with the corresponding reference code words provided by said second code storage means, and alarm indicator means controlled by said code word comparator means to provide an alarm indication whenever the code words compared are different.
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40. In a security system including a transmission line extending between first and second locations for permitting bidirectional transmission of information therebetween, first means at said first location including first line driver means connected to said transmission line and normally enabled to transmit data to said second location, and first line receiver means continuously enabled to receive data transmitted to said first location from said second location for processing by a first data processing means, second means at said second location including second line receiver means continuously enabled to receive data transmitted to said second location from said first location for processing by a second data processing means, and second line driver means normally disabled and operable when enabled to transmit data to said first location, said second means including normally disabled gating means interposed between said second line receiver means and said second data processing means, and first control means responsive to the receipt of data from said first location to enable said gating means to gate said data to said second data processing means and for enabling said second line driver means to transmit further data to said first location, said first means including further normally disabled gating means interposed between said first line receiver means and said first data processing means, and second control means responsive to the data transmitted by said first line driver means to inhibit said first line driver means after a predetermined time and to enable said further gating means to permit said further data to be extended to said first data processing means.
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41. In a security system including a transmission line for permitting the transmission of information between a secured area and a monitoring area, monitoring means at said secured area including first code generating means having first multistage shift register means and first programmable feedback means having inputs connected between outputs of certain stages of said first shift register means and an output connected to an input of said first shift register means to provide feedback signals to enable said first shift register means to provide a line security code comprised of a known, pseudo-random sequence of code bits for transmission over said transmission line to said monitoring area, and receiver means at said monitoring area including second code generating means having second multistage shift register means and second programmable feedback means having inputs connected between outputs of certain stages of said second shift register means and an output connected to an input of said second shift register means to provide feedback signals to enable said second shift register means to provide a reference code comprised of a pseudo-random sequence of code bits which is identical to the line security code sequence for comparison with the line security code sequence to permit an indication to be provided whenever compared bits differ, and means for enabling the conections of the inputs of said first and second feedback means to the outputs of said first and second shift register means, respectively to be changed periodically to vary the known pseudo-random code sequences provided by said first and second code generating means.
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42. In a security system including a transmission line extending between a secured area and a monitoring area, apparatus for securing the transmission line and for enabling the transmission of information between said monitoring and secured areas, said apparatus comprising first code generating means at said secured area operable to provide a code word for use in the generation of a line security code for transmission over said transmission line to the monitoring area, second code generating means at said monitoring area operable to provide a code word for use in the generation of a reference code for comparison with the line security code transmitted from the secured area, and synchronizing means for providing a first signal for application to said first and second code generating means, means for synchronizing the operation of said first and second code generating means to enable said first and second code generating means to provide identical codes and reset means responsive to a further signal provided by said synchronizing means to control said first and second code generating means to modify the code words for said first and second code generating means thereby modifying the identical codes provided by said first and second code generating means.
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43. In a security system including a transmission line extending between a secured area and a monitoring area, apparatus for securing the transmission line and for enabling the transmission of information between said monitoring and secured areas, said apparatus comprising first storage means at said secured area having a plurality of storage locations each storing a different one of a first plurality of different code words, second storage means at said monitoring area having a plurality of storage locations each storing a different one of a second plurality of code words which are identical with the code words stored by said first storage means, means for enabling sequential transmission of the code words of the first plurality to said monitoring area over said transmission line, means for receiving the code words of said first plurality transmitted over said transmission line, and for comparing each of the code words of said first plurality with a corresponding code word of said second plurality, and means for providing an alarm indication whenever the code words compared are different.
Specification