DATA TRANSFERRING SYSTEM UTILIZING A MONITOR CHANNEL AND LOGIC CIRCUITRY TO ASSURE SECURE DATA COMMUNICATION

• US 3,696,210 A
• Filed: 08/06/1970
• Issued: 10/03/1972
• Est. Priority Date: 08/06/1970
• Status: Expired due to Term

• Current Assignee: James W. Peterson, John A. Tempka
• Original Assignee: James W. Peterson, John A. Tempka
• Inventors: Peterson, James W., Tempka, John A.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Stewart, David L.
• Application Number:
  US05/061,729
• Time in Patent Office: 789 Days
• Field of Search: 179/15BP,15AD,2DP,15BF,15AE,15BY,1.5R 325/41,42,322,323,478
• US Class Current: 370/242
• CPC Class Codes: G08C 25/00 Arrangements for preventing or correcting errors; Monitoring arrangements
• CPC Class Codes: H02H 1/0061 concerning transmission of signals transmission of measured quantities or switching orders; sectionalised protection involving signal transmission between at least two stations H02H7/261; comparison of the voltage or current values at two spaced portions of a single system H02H3/28; transferring the output of a sensing member to another variable G01D5/00; electrical measuring arrangements using modulation of electromagnetic waves, e.g. light beams G01R15/24, G01R15/26
• CPC Class Codes: H02H 3/05 with means for increasing reliability, e.g. redundancy arrangements for logic circuits H03K19/003
• CPC Class Codes: H02J 13/00006 characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
• CPC Class Codes: H02J 13/0004 involved in a protection system
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04L 25/497 by correlative coding, e.g. partial response coding or echo modulation coding transmitters and receivers for partial response systems transversal equalizers at the transmitter end H04L25/03343
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/00 Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
• CPC Class Codes: Y04S 40/12 characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment

Abstract

The transmitter-encoder of the data transferring system utilizes polybinary, correlative encoding to develop an information carrying signal, which includes a monitor signal having a known data code, and data from a plurality of sources. The encoding techniques facilitates redundant bit transmission in a constrained bandwidth. The receiver-decoder includes monitor channel logic circuitry which determines whether the decoded signal is free from error. Moreover, each of the data decoding channels utilizes majority logic to verify that a particular control initiating signal is being received before the control signal is applied to data utilization devices associated therewith. If one error is detected in the monitor signal, the data channels are squelched for a first predetermined period of time thus preventing erroneous control signals from being applied to the utilization devices. If more than one error is detected in the monitor signal within a second predetermined period of time the data channels are squelched for a third predetermined period of time and an alarm is activated by the monitor channel-logic circuitry. As a result, the system provides security against abnormal transmission characteristics.

Claims

1. A data security system for discriminating against errors in data occurring in a data transfer system which transfers data originating at an output terminal of a data source to an output terminal of the data transfer system, the data security system including in combination:

monitor signal generator means adapted to provide a monitor signal of a known data code at its output terminal;

combiner means having a first input terminal connected to said output terminal of said monitor signal generator means and a second input terminal connected to the output terminal of the data source, said combiner means sequentially sampling the output signals of said monitor signal generator means and the data source to form a serial bit stream which is transferred by the data transfer system to the output terminal thereof;

bit stream separator means having an input terminal connected to the output terminal of the data transfer system and first and second output terminals, said bit stream separator means selectively providing signals originating at the data source to said first output terminal thereof and signals originating at said monitor signal generator means to said second output terminal thereof;

a data utilization device having an input terminal connected to said first output terminal of said bit stream separator means and a squelch input terminal, said data utilization device being rendered inoperative in response to a squelch signal applied to said squelch input terminal thereof;

logic means having an input terminal and a squelch output terminal, said input terminal of said logic means being connected to said second output terminal of said bit stream separator means, said logic means being responsive to any data code other than said known data code to produce a squelch signal at said squelch output terminal thereof; and

first circuit means connecting said squelch output terminal of said logic means to said squelch input terminal of said data utilization device so that said squelch signals provided by said logic means render said data utilization device inoperative.

2. The data security system of claim 1 further including:

majority logic means having an input terminal connected to said first output terminal of said bit separator means and an output terminal connected to said squelch input terminal of said data utilization device; and

said majority logic means being responsive to a particular information signal being applied thereto from said bit separator means a predetermined number of times within a predetermined time duration to provide a third control signal at its output terminal which renders said data utilization device inoperative.

3. The data security system of claim 1 wherein said logic means includes:

a monitor code logic circuit having an input terminal connected to said input terminAl of said logic means and an output terminal, said monitor code logic circuit providing a first control signal at said output terminal thereof in response to each application thereto of any data bit which is inconsistent with said known data code; and

control signal processing means connected from said output terminal of said monitor code logic means to said squelch output terminal of said logic means, said control signal processing means converting each of said first control signals into one of said squelch signals.

4. The data security system of claim 3 wherein said control signal processing means includes pulse shaping means connected between said output terminal of said monitor code logic circuit and said squelch output terminal of said logic means, said pulse shaping means providing a squelch signal at said squelch output terminal of said logic means of a first predetermined time duration in response to each of said first control signals.

5. The data security system of claim 3 wherein said control signal processing means further includes:

first timing means having an output terminal and an input terminal connected to said output terminal of said monitor code logic circuit and being responsive to a first one of said first control signals to provide a first initiating signal at its output terminal which has a second predetermined time duration;

second circuit means having an output terminal and a first input terminal connected to said output terminal of said monitor code logic circuit and a second input terminal connected to said output terminal of said first timing means, said second circuit means being responsive to said first initiating signal to provide a non-initiating signal at its output terminal;

said second circuit means being responsive to at least a second one of said first control signals occurring during said second predetermined time duration to provide a second initiating signal at its output terminal;

gate means having an output terminal, a first input terminal connected to said output terminal of said first timing means and a second input terminal connected to said output terminal of said second circuit means, said gate means producing a second control signal at its output terminal in response to the application thereto of said first and second initiating signals;

second timing means having an output terminal and an input terminal connected to said output terminal of said gate means and responding to said second control signal to provide a squelch signal at its output terminal having a third predetermined time duration; and

third circuit means coupling said output terminal of said second timing means to said squelch output terminal of said logic means.

6. The data security system of claim 4 further including:

alarm means connected to said output of said second timing circuit means.

7. A data transferring system, including in combination:

monitor signal source providing at its output a digital monitor signal having a known code;

a plurality of data sources each providing at its output a digital information signal to be transferred;

combiner means connected to said output of said monitor signal source and to the outputs of each of said plurality of data sources, said combiner means sequentially sampling said digital monitor signal and said digital information signals to form a serial, binary bit stream therefrom at its output;

encoding means connected to said output of said combiner means and transforming said serial, binary bit stream into a ternary waveform at its output;

decoding means coupled to the output of said encoding means and converting said ternary waveform back into said serial, binary bit stream at its output;

bit separator means connected to the output of said decoding means and applying said digital monitor signal to a monitor signal output thereof and each of said plurality of digital information signals to each of a plurality of corresponding information output terminalS;

said digital monitor signal tending to have error bits occurring therein in sequence with error bits occurring in said digital information signals;

each of a plurality of data utilization devices connected to each of said plurality of information output terminals of said bit separator means;

monitor signal processing means coupled to said monitor signal output of said bit separator means, said monitor signal processing means being responsive to each of said error bits in said digital monitor signal to provide a squelch signal at a squelch output terminal thereof; and

said squelch output terminal being connected to each of said plurality of data utilization devices so that said squelch signal renders the same inoperative during the duration thereof.

8. The data transferring system of claim 7 wherein said monitor signal processing means includes:

monitor code logic means providing a first control signal at an output terminal thereof in response to each application thereto of one of said error bits; and

control signal processing means connected from said output terminal of said monitor code logic means to said squelch output terminal and converting each of said first control signals into one of said squelch signals.

9. The data transferring system of claim 8 wherein said control signal processing means includes pulse shaping means connected between said output terminal of said monitor code logic means and said squelch output terminal, said pulse shaping means providing a squelch signal at said squelch output terminal having a first predetermined time duration in response to each of said first control signals.

10. The data transferring system of claim 9 wherein said control signal processing means further includes:

first timing means connected to said output terminal of said monitor code logic means and being responsive to a first one of said first control signals to provide a first initiating signal at its output terminal having a second predetermined time duration;

second circuit means also connected to said output terminal of said monitor code logic means, said second circuit means being responsive to said first one of said first control signals to provide a non-initiating signal at its output terminal, said second circuit means being responsive to a second one of said first control signals occurring during said second predetermined time duration to provide a second initiating signal at its output terminal;

gate means having a first input terminal connected to the output terminal of said first timing means and a second input terminal connected to the output terminal of said second circuit means, said gate means producing a second control signal at its output terminal in response to the simultaneous application of said first and second initiating signals to its first and second input terminals;

second timing circuit means having an input terminal connected to said output terminal of said gate means and responding to said second control signal to provide a squelch signal having a third predetermined time duration at its output terminal; and

, third circuit means coupling the squelch signal having a third predetermined time duration to said squelch output terminal.

11. The data security system of claim 10 further including:

alarm means connected to said output terminal of said second timing circuit means and being activated by said squelch signals applied thereto, said third circuit means having a unidirectional coupling means which conducts said squelch signals having a third predetermined time duration to said squelch output terminal, said unidirectional coupling means preventing said squelch signals of a first predetermined time duration from being applied to said alarm means.

12. The data transferring system of claim 7 wherein each of said plurality of data sources includes measuring means for monitoring electrical quantities on a power line and developing said digital information signal in response thereto, and each of said data utilization devices includes protective means for selectively removing electrical power from said power line in response to a third control signal.

13. The data transferring system of claim 12 wherein each of said plurality of data utilization devices further includes:

majority logic means which is responsive to a particular information signal having been applied thereto a predetermined number of times within a fourth predetermined time duration to provide said third control signal at its output.

14. The data transferring system of claim 7 further including transmission means connecting said encoding means to said decoding means, said transmission means having a selected band pass characteristic.

15. The data transferring system of claim 14 wherein said transmission means is a transmission line.

16. The data transferring system of claim 12 wherein said encoding means has polybinary correlative encoding means including:

first signal means forming a first encoded signal comprised of a modulo-two addition of said serial binary bit stream and said first encoded signal which is delayed by two bits;

second signal means forming said ternary signal at its output terminal by adding the inverse of said first encoded signal delayed by two bits to said first encoded signal, said ternary signal thereby having a sine function frequency spectrum; and

, low pass filter means connected to said output terminal of said second signal means and selecting said frequency components of said ternary waveform within a first recurring portion of said sine function frequency spectrum to provide a filtered ternary waveform at its output terminal.

17. The data transferring system of claim 14 wherein said encoding means includes:

generator means providing a constant frequency sinusoidal signal at its output terminal, modulator means connected to said output terminal of said frequency generator means and said output terminal of said low pass filter, said modulator means amplitude modulating said constant frequency sinusoidal signal with said filtered ternary signal to produce a sideband at its output terminal having a frequency spectrum included in said selected bandpass characteristic of said transmission means;

band pass filter means being connected to said output terminal of said modulator means and providing said sideband at its output terminal; and

said transmission means coupling said sideband to said decoding means.

18. The data transferring system of claim 17 wherein said decoding means includes:

mixing means deriving said filtered ternary signal from said sideband and providing the filtered ternary signal at its output; and

slicing means converting said filtered ternary signal back into said serial binary bit stream.

19. The data transferring system of claim 7 wherein:

said monitor signal is comprised of a square wave having a first repetition rate;

said combiner means sequentially samples said monitor signal source and each of said plurality of data sources during every half cycle of said monitor signal to form said binary bit stream; and

, said digital information signal has a second repetition rate no greater than said first repetition rate multiplied by the number of said plurality of said data sources plus one.

20. A data transferring system for communicating a digital information signal occurring at the output terminal of at least one data source to a data utilization device at a desired location, the system including in combination:

monitor signal source having an output terminal and providing a digital monitor signal having a known code at such output terminal;

combiner means having an output terminal, a first input terminal connected to said output terminal of said monitor signal source and a second input terminal connected to the output terminal of the data source, said combiner means sampling said digital monitor signal during a predeteRmined time period and said digital information signal to form a binary bit stream therefrom at its output terminal;

encoding means having an output terminal and an input terminal connected to said output terminal of said combiner means for transforming said binary bit stream into a second bit stream at its output terminal;

communication link means for connecting said encoding means to decoding means;

decoding means having an output terminal, a squelch input terminal and a data input terminal, said data input terminal being coupled to said communication link means, said decoding means converting said information signal back into said binary bit stream at its output terminal;

a data utilization device having an input terminal connected to said output terminal of said decoding means, said data utilization device being responsive to the digital information signal originating at the data source;

logic means having an input terminal connected to said output terminal of said decoding means, said logic means being responsive during a time period corresponding to said predetermined time period to data codes other than said known data code to provide a squelch signal at a squelch output terminal thereof; and

first circuit means connecting said squelch output terminal of said logic means to said squelch input terminal of said decoding means, said squelch signals rendering said decoding means inoperative for predetermined time durations so that error signals occurring in said binary bit stream at said output terminal of said decoding means are not applied to said data utilization device.

21. The data transferring system of claim 20 wherein said communication link means includes a sine function filter.

22. The data transferring system of claim 20 further including in combination:

timing generator means for developing a plurality of timing signals all of which are synchronized with each other and for applying such timing signals to a corresponding plurality of output terminals;

second circuit means connecting one of said plurality of output terminals of said timing generator means to said monitor signal generator so that one of said timing signals is applied thereto;

third circuit means connecting one of said plurality of output terminals of said timing generator means to said combiner means so that one of said timing signals is applied thereto;

fourth circuit means connecting one of said plurality of output terminals of said timing generator means to said encoding means so that one of said timing signals is applied thereto;

fifth circuit means connecting one of said plurality of output terminals of said timing generator means to said communication link means so that one of said timing signals is applied thereto, said communication link means transferring said timing signal applied thereto to said decoding means; and

said timing signals synchronizing the operation of said monitor signal generator, combiner means, encoding means and said decoding means.