Aclara Power-line Systems Inc.

Other

Aclara Technologies, LLC

Distribution Control Systems, Inc.

Quentin H Spencer

David W Rieken

John B Hessling, Jr

Benjamin A Hammond

Dennis L Kelley

William J Davis

Michael R Walker, Ii

A method of detecting a signal transmitted over one phase of a multi-phase power distribution system, components of the signal concurrently appearing on all phases of the system. The method includes detecting the components of each signal appearing on each phase, including neutral, of the system. Detected signals are provided to a signal processor which processes them to produce a detected signal which is a composite of all the components. The signals are combined by a weighted summation scheme that takes into account signal and noise correlation properties to simultaneously maximize signal strength and suppress noise. If other signals are present on other phases of the system, any resulting interference is canceled out from the detected signal to further improve the quality of the detected signal.

Simultaneous detection of communications signals on all phases of a multi-phase power distribution network

Improvements in the detection of TWACS outbound message signals. A first improvement involves matching some (or all) of the intermediate points in an outbound preamble occurring between bits of the preamble currently being detected. This reduces the possibility of a false synchronization and therefore decreases the probability of missing outbound message signals. A second improvement is to require some or all of the known preamble bits to exceed a predetermined threshold where both the thresh-old and which bits are adjustable. An additional approach is using 4-8 additional buffers in a transponder to detect preamble patterns in the outbound message. Each half cycle of the outbound message waveform requires entering a bit only into the buffers active for the particular frame of reference in which the message is being transmitted, since only buffers for that frame of reference are employed. The process continues until all bits specified to be sent, based on the length of the outbound message, are extracted. A CRC is then performed for the message. Using this method eliminates the problem of inbound messages being detected as outbound messages, and the resulting 'blindness' of the transponder. It further makes the transponders less sensitive to noise which currently causes the transponder to detect a preamble when there is none, resulting in a valid outbound message being missed.

Detection of outbound message signals in a power line two-way communications system

A method for use in a power line communication systems for an electrical distribution system () to quickly and accurately poll electrical meters () installed at user facilities to determine if an outage has occurred at a facility. An outbound communications message is transmitted to the meter at the facility requesting a short response consisting of a bit pattern that is either partially or completely known to the receiver. Any perceived response from the meter is then processed to ascertain whether or not the meter actually transmitted a message. Receipt of a message indicates that an outage has not occurred at that site, while an indication the message was not received indicates an outage has likely occurred. In processing the received message, two types of errors can potentially occur; i.e., a false positive or a false negative.

Detection of fast poll responses in a TWACS inbound receiver

A method for producing a set of inbound pulse patterns and detection vectors for lengths longer than 4 cycles in an AC waveform. These are used for generating inbound messages in a two-way automatic communication system (TWACS). The method uses Hadamard matrices adapted to generate a set of detection vectors by permuting rows of a matrix and removing certain columns of the matrix to meet system design requirements. The method can be extended to any length and modified to accommodate multiple pulses per half-cycle to support higher data rates.

General method for low-frequency data transmission on a power line

A method for use in a power line communication systems for an electrical distribution system () to quickly and accurately poll electrical meters () installed at user facilities to determine if an outage has occurred at a facility. An outbound communications message is transmitted to the meter at the facility requesting a short response consisting of a bit pattern that is either partially or completely known to the receiver. Any perceived response from the meter is then processed to ascertain whether or not the meter actually transmitted a message. Receipt of a message indicates that an outage has not occurred at that site, while an indication the message was not received indicates an outage has likely occurred. In processing the received message, two types of errors can potentially occur; i.e., a false positive or a false negative. A false positive occurs when a detection algorithm used to process the response indicates that the meter sent a response when actually it did not. A false negative occurs when the detection algorithm indicates the meter did not send a response when actually it did. The method utilizes a signal processing algorithm to determine if a response was actually sent by the meter and is important because it minimizes the probability of both types of errors.

A method of correcting errors in a message transmitted over a digital communication channel, where the message was encoded using a CRC for purposes of error detection. A parity-check matrix representation of the CRC is computed for any fixed-length message, and that parity-check matrix is combined with the parity-check matrix for any error correcting code that used in conjunction with the CRC. The combined parity-check matrix is extended using sparsification algorithms to allow it to work well under a message passing decoder (MPD). Received messages are decoded using the message passing decoder, making it possible to correct more errors than if the CRC were decoded in a conventional manner.

Method of correcting message errors using cyclic redundancy checks

A method of data compression for use in a data communication's system for an electrical utility or the like to affect the most efficient transfer of data. The data is first formed into a forming a block (B). A parameter (M) is selected from among a group of parameters. Each data value in the block is divided by the selected parameter to produce, for each data value, a quotient (q=&#x2514;n/M&#x2518;) and a remainder (r=n&#x2212;qM). The quotient of each data value is encoded using unary coding in which the value for the quotient is encoded by transmitting an appropriate number of zeroes followed by a one. The remainder of each data value is encoded using binary encoding, and the resultant encoded block of data is then transmitted. The data values comprising the block of data are positive integer values and the encoding employs a Golomb-Rice code defined by a positive integer parameter.

Compression scheme for interval data

A set of irregular LDPC (Low Density Parity Check) codes having a pseudo-random structure and low encoding complexity. A block-cyclic LDPC code has an irregular row or an irregular column weight and includes a parity check matrix and an encoding matrix each of which has a pseudo-random structure. This allows the code to have the irregular row weight or irregular column weight together with an overall randomness to the code structure. Blocks within the code can be shortened, adjacent blocks of code can be overlapped, and adjacent columns within a block can be arbitrarily permuted so to change the weighting of rows and columns. The LDPC codes are particularly useful in two-way communications system for an electrical distribution system () to restore data lost or corrupted during its transmission.

Set of irregular LDPC codes with random structure and low encoding complexity

A 'super-fast' polling method for electrical meters for outage detection. In response to a query, a large group of electric meters (M) all simultaneously transmit reply signals over an electrical distribution network using TWACS&#xae;. The signals are separated by an inbound detector (IB) at a receiving end of the network. This allows a very large number of meters to be polled in a very short period of time to determine whether or not an outage has occurred at the location of each meter. Each meter transmits a bit pattern, and bit patterns are designed so a group of meter units can transmit their patterns simultaneously over a power line (L) to the inbound detector. The presence or absence of a bit pattern in the received signal conveys the presence or absence of the associated meter in the system. The ability to transmit multiple bit patterns in parallel requires that they be orthogonal to each other. The Hadamard matrices are a class of matrices whose rows could be used as a set of bit patterns. In addition to super-fast polling for outage detection, the method of the invention can also be used to poll meters for the presence of an alarm condition, as well as for both outage detection and an alarm condition.

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St. Louis, MO, United States of America

Quentin H Spencer