Method for communication utilizing multi-mode reception

• US 4,559,520 A
• Filed: 06/23/1982
• Issued: 12/17/1985
• Est. Priority Date: 06/23/1982
• Status: Expired due to Fees

• Current Assignee: New England Power Service Company
• Original Assignee: New England Power Service Company
• Inventors: Johnston, Reed H.
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/391,170
• Time in Patent Office: 1,273 Days
• Field of Search: 340/310 R, 340/310 A, 370/19, 370/119, 375/37, 375/58
• US Class Current: 370/203
• 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 2203/5433 Remote metering
• CPC Class Codes: H04B 2203/5466 using three phases conductors
• CPC Class Codes: H04B 2203/5495 having measurements and testing channel
• CPC Class Codes: H04B 3/542 the information being in digital form

Abstract

A method for improving signal quality while simultaneously enhancing the data rate in a communications system in which individual signaling events are, at least in principle, capable of representing a bit of digital intelligence. When the method is applied to power-line communication systems, the pattern of signaling events extends over some integer multiple of four cycles of the power-line wave. Signaling events of each particular type are found in exactly half of the cycles contained in any pattern. Patterns containing but one type of signaling event are arranged into orthogonal patterns--the term orthogonal implying that each pattern can be sensed only by a detection mode that maximizes the signal therefrom, and the application of any detection mode to a pattern for which it is not optimum will result in no net accumulation of signal. When two types of independent signaling events which yield signals of comparable magnitude are achieved they are arranged into pseudo-orthogonal patterns to further expand the data rate without impairing signal quality. Under these conditions quaternary coding proves to be the preferred technique. Examples are given wherein a multiplicity of simultaneous noninterfering messages are transmitted under circumstances where it is possible to transmit them in synchronism. Where multiple messages cannot be synchronized the method can be used to increase the data rate through the use of encoding schemes based on numerical bases greater than binary.

Claims

1. A method, applicable to communicating schemes on electric powerlines wherein a single signaling event of at least one type is in principle capable of representing a binary bit, whereby one may simultaneously improve signal quality and increase data rate, the said method comprising the steps of:

(i) representing every element of digital intelligence in terms of a pattern from a selected family of orthogonal patterns, where such selected family of patterns is comprised exclusively of signaling events of the same, at least one, type and where each pattern extends over an interval corresponding to the same integer multiple of four periods of the powerline frequency, and wherein the signaling events comprising each pattern are located in exactly half of the cycles contained in said pattern, each said pattern of signaling events being impressed upon the electric powerline at a transmitting site;

(ii) for the recognition of a pattern from the selected family of orthogonal patterns, employing at the receiving site a multiplicity of simultaneous detection modes, in number equal to half the number of patterns in the selected orthogonal family, and operating in such fashion that for each detection mode samples from corresponding portions of successive cycles in the pattern are combined in an equal number of additive and subtractive operations so as to accumulate signal from, and distinguished between, the pair of patterns with which that detection mode is uniquely associated, yet fail to accumulate signal from any pre-existing periodic background or from any pattern of the selected orthogonal family other than the pair of patterns with which the detection mode is uniquely associated;

(iii) processing the signals accumulated in the various detection modes so as to recognize the, at least one, transmitted pattern, which represents the element of digital intelligence and thereby to infer each element of digital intelligence conveyed within the interval corresponding to the same integer multiple of four periods of the powerline frequency.

2. The method of claim 1 wherein two independent selected orthogonal families of patterns, formed from two independent types of signaling events, are employed in combination to create a single pseudo-orthogonal family of twice the size of each of the independent families.

3. The method of claim 2 used for the transmission of a succession of single digits of a number system of a base greater than two wherein a single pattern of signaling events is used to represent each such digit.

4. The method of claims 1 or 2 wherein a multiplicity of transmitters operating in synchronism is employed at the same transmitting site for the simultaneous transmission of a plurality of digits.

5. The method of claims 3 wherein a preamble to the message proper is employed to establish the required synchronism between the receiving site and the transmitter.

6. The method of claim 2 wherein one employs quaternary coding in such a manner as to insure that any detection mode which senses a ghost signal will not simultaneously be sensing one of the pair of patterns with which it is properly associated.

7. The method of claim 1 wherein the selected orthogonal family comprises a majority subfamily and at least one minority subfamily so characterized that patterns within the majority subfamily do, and patterns within the minority subfamily do not, exhibit high immunity to noise attributable to a single step in background signaling occurring within the duration of a pattern, with the intent that patterns from the majority subfamily are, and patterns from the minority subfamily are not, used for the representation of elements of digital intelligence.

8. The method of claim 2 wherein the selected pseudo-orthogonal family consists of a majority subfamily and at least one minority subfamily so characterized that patterns within the majority subfamily do, and patterns within the minority subfamily do not, exhibit high immunity to noise attributable to a single step in background signal occurring within the duration of a pattern, with the intent that patterns from the majority subfamily are, and patterns from the minority subfamily are not, used for the representation of elements of digital intelligence.

9. The method of claim 1 wherein step (ii) includes a means for implementing the multiplicity of detection modes whereby the samples from the corresponding portions of successive cycles are digitized, and these digitized samples are then combined in additive and subtractive operations as prescribed in a microprocessor, so as to produce in successive digital outputs from the single microprocessor, digitized quantities which will correspond to the signals resulting from the multiplicity of detection modes.

10. The method of claim 4 wherein a preamble to the message proper is employed to establish the required synchronism between the receiving site and the transmitter.