Inbound interference reduction in a broadband powerline system

• US 7,091,849 B1
• Filed: 05/06/2004
• Issued: 08/15/2006
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Henry, Paul Shala
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): BUGG, GEORGE A
• Application Number:
  US10/840,096
• Time in Patent Office: 831 Days
• Field of Search: 340/538.12
• US Class Current: 340/538.12
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 3/30 Reducing interference caused by unbalanced currents in a normally balanced line
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals
• CPC Class Codes: H04J 1/08 Arrangements for combining channels branching filters H01P1/213, H03H7/46
• CPC Class Codes: H04L 25/028 Arrangements specific to the transmitter end
• CPC Class Codes: H04L 25/10 Compensating for variations in line balance
• CPC Class Codes: H04L 5/0005 Time-frequency

Abstract

Disclosed is a method and apparatus for reducing inbound interference in a broadband powerline communication system. Data modulated on first and second carrier frequencies is received via respective first and second lines of the powerline system. A characteristic of at least one of the carrier signals (e.g., phase or amplitude) is adjusted at the receiver in order to reduce the effects of inbound interference on the transmission system. The adjustment parameters may be determined by adjusting the parameters, during a period of no data transmission, until the output of a differential receiver is zero.

Claims

1. A method for reducing the effects of inbound interference in a powerline transmission system comprising the steps of:

receiving a first signal on a first line of said transmission system, said first signal comprising a modulated carrier signal component and an interference component;

receiving a second signal on a second line of said transmission system, said second signal comprising a modulated carrier signal component and an interference component;

adjusting at least one characteristic of at least one of said first and second signals to reduce the effects of external interference on said transmission system; and

determining adjustment parameters by adjusting said at least one characteristic of at least one of said first and second signals until the output of a differential receiver operating on said first and second signals is zero.

2. The method of claim 1 wherein said step of determining adjustment parameters is performed during a time period when data is not being transmitted via said powerline transmission system.

3. The method of claim 1 wherein said step of determining adjustment parameters is performed during a time period when data is being transmitted via said powerline transmission system.

4. The method of claim 1 wherein said at least one characteristic is signal phase.

5. The method of claim 1 wherein said at least one characteristic is signal magnitude.

6. The method of claim 1 wherein said powerline communication system is a frequency division multiplexed system transmitting data on a plurality of frequency channels.

7. The method of claim 6 wherein said step of adjusting is performed independently for each of said frequency channels.

8. Apparatus for reducing the effects of inbound interference in a powerline transmission system comprising:

means for receiving a first signal on a first line of said transmission system, said first signal comprising a modulated carrier signal component and an interference component;

means for receiving a second signal on a second line of said transmission system, said second signal comprising a modulated carrier signal component and an interference component;

an adjustment module for adjusting at least one characteristic of at least one of said first and second signals to reduce the effects of external interference on said transmission system; and

means for determining adjustment parameters by adjusting said at least one characteristic of at least one of said first and second signals until the output of a differential receiver operating on said first and second signals is zero.

9. The apparatus of claim 8 wherein said at least one characteristic is signal phase.

10. The apparatus of claim 8 wherein said at least one characteristic is signal magnitude.

11. The apparatus of claim 8 wherein said powerline communication system is a frequency division multiplexed system transmitting data on a plurality of frequency channels.

12. A powerline communication system comprising:

a first transmission line;

a second transmission line;

at least one receiver for receiving first and second modulated carrier signals via said first and second transmission lines respectively;

an adjustment module for adjusting at least one characteristic of at least one of said first and second carrier signals to reduce the effects of external interference on said transmission system;

wherein adjustment parameters are determined by adjusting said at least one characteristic of at least one of said first and second carrier signals until the output of a differential receiver operating on said first and second carrier signals is zero.

13. The powerline communication system of claim 12 wherein said at least one receiver is a differential receiver.