Method of receiving unsolicited messages on an electrical distribution network communications system

• US 5,486,805 A
• Filed: 07/06/1993
• Issued: 01/23/1996
• Est. Priority Date: 07/06/1993
• Status: Expired due to Term

• Current Assignee: Aclara Software, Inc. (ESCO Technologies, Inc.)
• Original Assignee: Aclara Software, Inc. (ESCO Technologies, Inc.)
• Inventors: Mak, Sioe T.
• Primary Examiner(s): Kostak, Victor R.
• Assistant Examiner(s): Miller, John W.
• Application Number:
  US08/086,085
• Time in Patent Office: 931 Days
• Field of Search: 340/310.01, 340/310.02, 340/310.06, 340/538, 340/825.08, 340/825.12, 340/825.13, 375/36, 375/37, 307/38
• US Class Current: 340/12.37
• CPC Class Codes: H04B 2203/542 using zero crossing information
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5495 having measurements and testing channel
• CPC Class Codes: H04B 3/544 Setting up communications; Call and signalling arrangements

Abstract

A two-way communication system (TWACS) used with an electrical power distribution network N. The TWACS provides both outbound and inbound messages to and from remote network locations. A method of detecting and decoding unsolicited inbound messages from remote locations first involves generating the message in response to a time independent event occurring at the remote location. Formation of the message includes both generating a series of message bits, each of which has a prescribed format, and affixing a preamble to the front end of the message which comprises a plurality of bits arranged in a predetermined pattern. The message is then transmitted over any one of a plurality of communication channels n normal used for two-way communications. Since the event triggering the unsolicited inbound message is independent of time, the time of transmission is random. The message is received at a receiving site, receipt of the message including receipt of the bits comprising the prefix together with bits comprising the message. The bits forming the preamble are detected, their detection signalling the fact an unsolicited message is being received. Preamble bit detection also initiate synchronization of operation of the TWACS to decode the contents of the message.

Claims

1. In a two-way communication system used with an electrical power distribution network, the communication system providing both outbound and inbound messages to and from remote network locations, a method of detecting and decoding unsolicited inbound messages from the remote locations comprising:

forming an unsolicited message at a remote location in response to the occurrence of a time independent event at that location, each message including a series of message bits each of which has a prescribed format, and a series of preamble bits arranged in a predetermined bit pattern at the beginning of the message;

transmitting the unsolicited message over any one of a plurality of selected communication channels normally used for two-way communications, said channels being selected for their relative immunity to noise;

receiving the unsolicited message at a receiving site, receiving the message including a receiver of the system being out of synchronization with the message, receipt of the message including first receiving the bits comprising the preamble, and then the bits comprising the message; and

,

detecting the bits comprising the preamble as an indication an unsolicited message is being received, detecting the bits including forming a matrix comprising a plurality of values derived from the detection of bits comprising the unsolicited message, the bit values within the matrix being arbitrarily set such that bits having a zero value are set at zero, bits having a value between zero and a first predetermined value are set at zero, bits having a value greater than the first predetermined value are set a second predetermined value, and bits having a value less than a fourth predetermined value are set at a fifth predetermined value thereby to compensate for the effects of noise on the power distribution network.

11. The method of claim 1 wherein receiving the message includes being out of synchronization with the message by up to five half-cycles.

2. In a two-way communication system used with an electrical power distribution network, the communication system providing both outbound and inbound messages to and from remote network locations, a method of detecting and decoding unsolicited inbound messages from the remote locations comprising:

forming an unsolicited message at a remote location in response to the occurrence of a time independent event at that location, formation of the message including generating a series of message bits each of which has a prescribed format, and affixing a preamble comprising a plurality of bits arranged in a predetermined pattern to the beginning of the message;

transmitting the unsolicited message over any one of a plurality of communication channels normally used for two-way communications, the time of transmission being random since the event causing generation of the message is time independent;

receiving the unsolicited message at a receiving site, receipt of the message including first receiving the bits comprising the preamble, and then the bits comprising the message; and

,

detecting the bits comprising the preamble as an indication an unsolicited message is being received;

synchronizing operation of the system with the messages based upon detection of the preamble bits detecting the bits including forming an input matrix based upon the bit values of a predetermined number of consecutive detected bits, and forming sequential input matricees with a new input matrix being formed each time the next bit is detected, each new input matrix including the newly detected bit as the lowest order bit with the highest order bit from the previous input matrix being discarded, and, applying a predetermined detection matrix to each input matrix regardless of the communication channel over which the unsolicited message is transmitted to produce a residue matrix, with values in the residue matrix being determined such that all residue values therein having a first value are set to a first predetermined magnitude, all residue values less than a second value are also set to the first predetermined magnitude, all values greater than the second value are set to a second predetermined magnitude, and all value less than a third value are set to a third predetermined value, thereby to adjust the residue values in the residue matrix to compensate for the effects of noise on the power distribution network.

3. The method of claim 2 wherein detecting the bits comprises monitoring pulses imposed on the current waveform of the distribution network when the message is generated.

4. The method of claim 3 wherein size of the input matrix the detection matrix and the resulting residue matrix corresponds to the number of pulses comprising the message preamble.

5. The method of claim 4 further including storing the residue matrix.

6. The method of claim 5 further including comparing the stored residue matrix with each residue matrix created by applying the detection matrix to an input matrix.

7. The method of claim 6 further including initiating synchronization of the network with the bits comprising the message contents when the value of the stored residue matrix compares with that of a residue matrix created when the detection matrix is applied to an input matrix, the comparison indicating a message preamble has been detected.

8. The method of claim 7 wherein the bit values of the stored residue matrix are commonly adjusted with those of the actual residue matricees.

9. The method of claim 7 further including setting the residue matrix bit values to predetermined values as a function of the absolute value of each bit.

10. The method of claim 9 further including setting the residue matrix bit values as a function of a calculated average value of the residue matrix.

12. In a two-way communication system used with an electrical power distribution network, the communication system providing both outbound and inbound messages to and from remote network locations, a method of detecting and decoding unsolicited inbound messages from the remote locations comprising:

forming an unsolicited message at a remote location in response to the occurrence of a time independent event at that location, each message including a series of message bits each of which has a prescribed format, and a series of preamble bits arranged in a predetermined bit pattern at the beginning of the message;

transmitting the unsolicited message over any one of a plurality of selected communication channels normally used for two-way communications, said channels being selected for their relative immunity to noise, and the respective bits comprising the preamble and the message comprising pulses imposed on a current waveform of the distribution network;

receiving the unsolicited message at a receiving site, receipt of the message including first receiving the bits comprising the preamble, and then receiving the bits comprising the message; and

,

synchronizing a receiver of the system with the message by detecting the bits comprising the preamble, said detecting including;

monitoring the pulses imposed on the current waveform;

forming a series of input matricees based upon the bit values of a predetermined number of consecutively detected bits, each input matrix including a predetermined number of bits with a new input matrix being formed each time the next bit is detected whereby the new input matrix includes the newly detected bit as the lowest order bit, the highest order bit from the previous input matrix being discarded;

applying a detection matrix to each input matrix and calculating a residue matrix in response thereto;

storing a residue matrix comprising values corresponding to the residue matrix created when the detection matrix is applied to an input matrix whose contents comprise the message preamble;

comparing the stored residue matrix with each residue matrix created by applying the detection matrix to an input matrix; and

,

initiating synchronization of the system with the bits comprising the message contents when the value of the stored residue matrix compares with that of a residue matrix created when the detection matrix is applied to an input matrix, the comparison indicating a message preamble has been detected wherein values in the residue matrix are determined by arbitrarily assigning bits having a value of zero or a value less than a first predetermined value a value of zero, bits having a value greater than the first predetermined value a second predetermined value, and a value less than a third predetermined value a fourth predetermined value.