Data communication system

• US 4,583,090 A
• Filed: 10/16/1981
• Issued: 04/15/1986
• Est. Priority Date: 10/16/1981
• Status: Expired due to Fees

• Current Assignee: BBC Brown Boveri & Company Limited (ABB Limited)
• Original Assignee: American Diversified Capital Corporation
• Inventors: Eden, Richard C., Deyhimy, Ira, Quilici, Timothy J.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/312,367
• Time in Patent Office: 1,642 Days
• Field of Search: 340/825.06, 340/825.07, 340/825.52, 340/825.58, 340/825.22, 340/825.69, 375/11, 375/17, 375/19, 375/20, 375/42, 375/52, 375/53, 375/83, 375/85, 375/86, 375/45, 375/54, 375/62, 375/67, 370/71, 370/72, 370/74, 370/76, 370/11
• US Class Current: 375/272
• CPC Class Codes: H04H 20/34 using an out-of-band subcarrier signal
• CPC Class Codes: H04H 2201/70 characterised in that receivers can be addressed
• CPC Class Codes: H04H 60/13 Arrangements for device control affected by the broadcast information

Abstract

A data communication system for general purposes having a new ternary carrier frequency shift keying (TCSK) signal. The system is applied to a utility load control by transmission of a sub-carrier of an FM broadcast channel. It is decoded by a receiver, SCA decoder, TCSK filter and a two level or binary converter and used to communicate to a pre-programmed microprocessor which enables various load control functions to be performed. The general system also is given for a QPSK (quadraphase shift keying) operating system.

A data transmission filter is split between the transmitter and receiver and is operated in cascade to give individual interference filtering at each end of the transmission while also providing combined action and wave shaping. A high accuracy FM decoder using zero crossing detection enables data recovery with simple circuits. A novel random time load restoration circuit for ramp-up is disclosed. A fail safe relay operator is also disclosed.

The TCSK employs a novel 19 character hex code format which is 8 bit microprocessor compatible and directly usable for other purposes such as ASCII message transmission. Both QPSK and TCSK systems offer command structures of variable length so as to permit truncation of message and reduce total message transmit time.

Claims

1. A load management system for controlling a plurality of user loads in a utility electrical power system containing a transmitter which sends a modulated radio wave signal to a plurality of receivers, each of which is connected to a different electrical load and includes means responsive to the modulated radio wave signal for controlling the load connected to the receiver comprising:

means for transmitting a signal in a ternary character shift keying (TCSK) code, said TCSK-coded signal including a control sequence with a preamble, an address identifier, a command signal, a data signal containing information for execution of the command signal, and a checksum signal; and

wherein each said load controlling means includes

means for receiving and decoding said TCSK-coded signal;

means coupled to said receiving and decoding means, for generating a data sync signal from said preamble, for generating a user enable signal from said address identifier, for generating a specific operating routine in response to said command signal, for processing said data signal in response to said command signal in accordance with said routine, for computing a checksum value from said TCSK-coded signal, for comparing the checksum signal with the computed checksum value, and for disabling said controlling means whenever said checksum signal and computed checksum value disagree.

2. The load management control system in claim 1 in which said TCSK code includes a symbol the transmission of which indicates a truncate command, and wherein each of said plurality of receivers includes means responsive to said truncate command to shorten transmission and reception times.

3. The load management control system in claim 1 in which each said load controlling means comprises a microprocessor to generate load control signals.

4. In a load management system for controlling a plurality of user loads in a utility electrical power system containing a transmitter which sends a modulated radio wave signal to a plurality of receivers each of which is connected to a different electrical load an includes means responsive to the modulated radio signal for controlling the respective load comprising:

means for transmitting via radio waves a signal in quadrature phase shift keying (QPSK) code;

means in each of said receivers for receiving and decoding said QPSK-coded signal into a binary digital signal, said coded signal including a control sequence with a preamble, an address identifier, a command signal, a data signal containing information for execution of the command signal, and a checksum signal; and

means in each said receiver coupled to said receiving and decoding for generating a data sync signal from said preamble, for generating a user enable signal from said address identifier, for generating a specific operating routine in response to said command signal for processing said data signal in response to said command signal, for computing a checksum value from the coded signal, for comparing the checksum signal with the computed checksum value; and

for disabling said load control functions whenever said checksum signal and checksum value disagree.

5. An electrical power control transmission system for communicating data, said transmission system comprising:

a transmitter for transmitting said data, said transmitter including a ternary character shift keying (TCSK) generator for encoding said data as a series of ternary bits and for transmitting a different frequency for each state of said ternary bits; and

a receiver coupled to said transmitter over a communication channel for receiving said transmitted data, said receiver including

an electrical load,

power relays for controlling said electrical load,

means for decoding said transmitted data into baseband data stream for operating said power relays to switch said electrical load, and

a fail safe circuit coupled to said relays and said decoding means to prevent improper operation of said system in case of system failures.

6. The communication system in claim 5 wherein said receiver includes a microprocessor, and said fail safe circuit includes a charge pump capacitor input into which the microprocessor continuously supplies a series of pulses to maintain said fail safe circuit in a microprocessor-controlled state.

7. A system for communicating data comprising

a transmitter for transmitting said data, said transmitter including a ternary character shift keying (TCSK) generator for encoding said data as a series of ternary bits and for transmitting a different frequency for each different state of said ternary bits;

and

a receiver coupled to said transmitter over a communication channel for receiving said transmitted data, said receiver including

a digital decoder for decoding said transmitted data and recovering a baseband data stream,

zero crossing generator means for developing a series of first pulses each corresponding to a different rising and falling edge of said baseband data stream,

pulse generator means responsive to said first pulses for generating a series of second pulses having uniform characteristics, each of said second pulses corresponding to a different one of said first pulses, and

means for generating a signal representing the average strength of said first pulses.

8. The communication system in claim 7 wherein said pulse generator includes means for generating pulses having constant width whose frequency varies as a function of the zero crossing pulses received, and

wherein said receiver further includes amplitude detection means for generating a baseband amplitude signal to the frequency the frequency of said pulses.

9. A load management system for controlling a plurality of user loads in a utility electrical power distribution system including a transmitter which sends a radio wave signal to a plurality of receivers each of which is associated with a different one of said user loads, said transmitter including a computer, a radio wave transmitter, and a communication link connecting said computer to said radio wave transmitter, said radio wave transmitter including means for generating a ternary character shift keying (TCSK) encoded signal from binary outputs of said computers, said encoded signal consisting of 4 bit ternary chips;

each said receiver including means for decoding said TCSK encoded signal into a digital signal, and means for processing said digital signal.

10. A system for communicating data comprising:

a transmitter for transmitting said data, said transmitter including

a ternary character shift keying (TCSK) generator for encoding said data as a series of ternary bits and for transmitting a different frequency for each different state of said ternary bits, and

first means for filtering said data stream to reduce the energy outside a predetermined frequency range necessary for transmission of said ternary bits; and

a receiver coupled to said transmitter over a communication channel for receiving said transmitted data, said receiver including

second means for filtering out noise and co-channel interference from said communication channel, and

means for decoding said transmitted data into a baseband data stream,

said first and second filtering means being constructed and arranged to form a cascade pair for wave shape control of said transmitted data.

11. The communication system in claim 10 in which said first and second filtering means are a cascaded matched pair designed to cooperate to pass a step function while eliminating interference to or from other sources or users.

12. The communication system in claim 10 in which said first and second filtering means combine to form, in cascade, a combination filter having a predetermined transmission property for wave shaping said transmission.

13. The communication system in claim 12 in which said cascaded combination is a Bessel filter.

14. The communication system in claim 13 in which said Bessel filter is a even pole filter having one-half thereof at the transmitter and the other half at the receiver, each of said halves being identical.

15. A system for communicating electrical load control data comprising:

a transmitter for transmitting said data, said transmitter including a ternary character shift keying (TCSK) generator for encoding said data as a series of ternary bits and for transmitting a radio wave signal at a different frequency corresponding to each different state of said ternary bits; and

a plurality of receivers each coupled to said transmitter over a different communication channel for receiving said transmitter data, each said receiver including

an electrical load,

means for controlling said electrical load,

means for receiving and decoding said transmitted data into a baseband data stream in binary format, and

microprocessor means coupled to said receiving and decoding means for receiving said baseband data in binary format and for developing a preamble to obtain a synchronization signal, an address identifier to provide a user enable function, and a data recognition command signal, thereby to direct said load controlling means to control said electrical load.

16. The communication system in claim 15 wherein said transmitter includes means for forming a truncate code and

wherein each of said receivers includes means forming a response to said truncate code for shifting said receiver operation from an address message receive function to a command message receive function.

17. A system for communicating data comprising:

a transmitter for transmitting said data, said transmitter including a ternary character shift keying (TCSK) generator for encoding said data as a series of data chips, each said chip comprising four ternary bits, and for transmitting a different frequency for each different state of said ternary bits, one of said frequencies being a center frequency and the other frequencies being offset from said center frequency by an equal amount, said TCSK generator forming said data chips such that the net frequency of the transmitted ternary bits for each said data chip equals said center frequency; and

a receiver coupled to said transmitter over a communication channel for receiving said transmitted data, said receiver including means for decoding said transmitted chips into a baseband data stream.

18. A method of communicating in a load management system including a master computer sending commands to a remote user, said method comprising the steps of:

generating load control commands;

translating said load control commands into a three level logic state system;

transmitting said translated load control commands via a frequency shift keying format wherein each state of said three level logic state system corresponds to a different frequency and the average frequency of all said commands equals the middle one of said different frequencies; and

decoding said frequency shift keyed commands at said remote users.

19. The method of claim 18 wherein said transmitting step includes the step of modulating an SCA channel.

20. The method of claim 19 wherein said modulating step includes the step of modulating said SCA channel to prevent co-channel interference with another user of said SCA channel.

21. The method of claim 20 further including the steps of:

forming chips including four digits of said three level logic state system, and

ensuring that the average frequency of each of said chips is said middle frequency.

22. A method of communicating in a load management system including a master computer sending commands to a remote user, said method including the steps of:

generating load control commands;

translating said load control commands into trinary chips, each chip being composed of four digits from a three level logic system;

said levels being denoted by +, N, and -,

using only chips having the same number of + digits as - digits;

frequency modulating a carrier frequency of an SCA channel according to said translated commands, wherein said + digit corresponds to a frequency f_N +f, said N digit corresponds to a frequency f, and said - digit corresponds to a frequency f_N -f; and

decoding, at said remote user, said frequency modulated commands.

23. The method of claim 22 further including the steps of assigning a different hexadecimal digit to sixteen of said chips having the same number of + digits as - digits and assigning a different control character to each of the other chips having the same number of + digits as - digits.