Power line communication system using anti-resonance isolation and virtual earth ground signaling

• US 6,417,762 B1
• Filed: 03/30/2001
• Issued: 07/09/2002
• Est. Priority Date: 03/30/2001
• Status: Expired due to Fees

• Current Assignee: C.O.B. Cybercircuits
• Original Assignee: Comcircuits
• Inventors: Comer, Donald T.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Previl, Daniel
• Application Number:
  US09/822,695
• Time in Patent Office: 466 Days
• Field of Search: 340/310.01, 340/310.02, 340/310.03, 340/310.05, 340/310.07, 340/310.08, 340/538, 375/259
• US Class Current: 375/260
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5441 Wireless systems or telephone
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines

Abstract

A method and system for transmitting and receiving high-frequency electrical communication signals over a previously installed building power line network is presented, in which minimal or no electrical modifications of the power line network are required. A high-frequency signal is impressed between earth ground/neutral and building ground power lines that are tied into a common ground bar at a service panel. The high-frequency signal isolates the earth ground line/neutral and building ground lines by creating an “anti-resonant” condition. Since building ground is required by electrical safety codes to be present at all electrical outlets within the building, the carrier signals can be transmitted and received from any electrical outlet within the building. The high-frequency communication signals are not impressed on load carrying wires of the power line network, and are consequently not subject to the bandwidth, noise and high-voltage problems associated with other power line communication methods.

Claims

1. A method for carrying a signal in a building power line network that includes a neutral line of the building power line network and a building ground line of the building power line network, wherein the neutral line and the building ground line are capacitively coupled together and connected to an earth ground, the method comprising the acts of:

selecting a frequency that is capable of electrically isolating the first line from the second line by creating an anti-resonant condition between the first line and the second line;

generating a carrier signal that has the selected frequency with a transmitter that is electrically coupled with the neutral line and the building ground line;

applying a first tuning function between the neutral line and a hot line included in the building power line network; and

applying a second tuning function between the neutral line and the building ground line, the first tuning function and the second tuning function being selected to increase the capacitance between the neutral line and the earth ground and to decrease the capacitance between the building ground line and the earth ground at the selected frequency;

modulating the carrier signal with an information signal such that the carrier signal carries information; and

impressing the modulated carrier signal between the first line and the second line, such that the anti-resonant condition is established between the first line and the second line.

2. A method as recited in claim 1, further comprising the acts of:

applying a third tuning function between the building ground line and a chassis of the transmitter; and

applying a fourth tuning function between the neutral line and the chassis, the third tuning function and the fourth tuning function being selected to increase the capacitance between the neutral line and the earth ground and to decrease the capacitance between the building ground line and the earth ground at the selected frequency.

3. A method for carrying a signal in a building power line network that includes a neutral line and a building ground line that are capacitively coupled together and connected to an earth ground, and a conductive conduit system that is electrically connected to the building ground line, the method comprising the acts of:

selecting a frequency that is capable of electrically isolating the neutral line from the building power line by creating an anti-resonant condition between the neutral line and the building power line;

generating a carrier signal that has the selected frequency;

applying a first tuning function between the building ground line and the conduit system, the first tuning function being selected to electrically isolate the building ground line from the conduit system at the selected frequency; and

applying a second tuning function between the neutral line and the conduit system, the second tuning function being selected to increase the capacitance between the first line and earth ground at the selected frequency;

modulating the carrier signal with an information signal such that the carrier signal carries information; and

impressing the modulated carrier signal between the neutral line and the building ground line, such that the anti-resonant condition is established between the first line and the second line.

4. A method for carrying a signal in a building power line network that includes a neutral line, a building ground line, and an earth ground that are connected one to another with a bus and further includes a conductive conduit system that is electrically connected to the building ground line, the method comprising the acts of:

providing a first tuning element that applies a first tuning function between the building ground line and the conduit system;

providing a second tuning element that applies a second tuning function between the neutral line and the conduit system;

selecting a frequency that, in combination with the first tuning element and the second tuning element, is capable of electrically isolating the neutral line from the building ground line by creating an anti-resonant condition between the neutral line and the building ground line;

generating a carrier signal that has the selected frequency;

modulating the carrier signal with an information signal such that the carrier signal carries information; and

impressing the modulated carrier signal between the neutral line and the building ground line, such that the anti-resonant condition is established between the neutral line and the building ground line.

5. A method as recited in claim 4, wherein the second tuning element comprises a capacitor positioned between the neutral line and the conduit system.

6. A method as recited in claim 5, wherein the first tuning element comprises an inductor positioned between the building ground line and the conduit system.

7. A method as recited in claim 5, wherein the first tuning element comprises a transformer positioned between the building ground line and the conduit system.

8. A method as recited in claim 5, wherein:

the act of generating the carrier signal is performed by a transmitter electrically coupled with the neutral line and the building ground line through a first power outlet in a building that includes the building power line network; and

the act of demodulating the carrier signal is performed by a receiver electrically coupled with the neutral line and the building ground line through a second power outlet in the building.

9. A method as recited in claim 4, wherein the act of impressing the modulated carrier signal is performed at a first location in the building power line network, the method further comprising the act of demodulating the carrier signal at a second location in the building power line network so as to obtain the information carried thereby.

10. A method as recited in claim 4, wherein the first tuning element and the second tuning element enhance one of a transmission line effect and an antenna effect.

11. A transmitter for transmitting a modulated carrier signal onto a building power line network that includes a neutral line, a building ground line, and an earth ground that are connected one to another with a bus such that the modulated carrier signal can be received at another location in the building power line network, the transmitter comprising:

a carrier signal generator that generates a carrier signal having a selected frequency that is capable of creating an anti-resonant condition between the neutral line and the building ground line;

a first tuning element for applying a first tuning function between the neutral line and a hot line included in the building power line network; and

a second tuning element for applying a second tuning function between the neutral line and the building ground line, the first tuning function and the second tuning function being selected to increase the capacitance between the neutral line and the earth ground and to decrease the capacitance between the building earth line and the earth ground at the selected frequency, whereby the first tuning function and the second tuning function enhance an antenna effect;

a modulator that modulates the carrier signal with an information signal such that the carrier signal includes information encoded in the information signal; and

electrical conductors adapted to be electrically coupled with the neutral line and at the building ground line for impressing the modulated carrier signal between the neutral line and the building ground line, the selected frequency electrically isolating the neutral line from the building ground line by creating the anti-resonant condition.

12. A building power line network that is capable of transmitting information signals between a first location and a second location of a building in which the building power line network resides without requiring a service panel of the building power line network to be modified to electrically isolate a first line of the building power line network from a second line of the building power line network, the building power line network comprising:

a neutral line;

a building ground line;

an earth ground;

a service panel at which the neutral line, the building ground line, and the earth ground are conductively connected one to another with a bus;

a transmitter electrically connected with the neutral line and the building ground line, the transmitter including;

a first tuning element for applying a first tuning function between the neutral line and a hot line included in the building power line network;

a second tuning element for applying a second tuning function between the neutral line and the building ground line, the first tuning function and the second tuning function being selected to increase the capacitance between the neutral line and the earth ground and to decrease the capacitance between the building ground line and the earth ground at the selected frequency, whereby the first tuning function and the second tuning function enhance an antenna effect; and

means for impressing a modulated carrier signal between the neutral line and the building ground line, the modulated carrier signal having a frequency that is selected to electrically isolate the neutral line and the building ground line by creating an anti-resonant condition between the neutral line and the building ground line.

13. A building power line network as recited in claim 12, further comprising:

a third tuning element for applying a third tuning function between the building ground line and a chassis of the transmitter; and

a fourth tuning element for applying a fourth tuning function between the neutral line and the chassis, the third tuning function and the fourth tuning function being selected to increase the capacitance between the neutral line and the earth ground and to decrease the capacitance between the building ground line and the earth ground at the selected frequency, whereby the third tuning function and the fourth tuning function further enhance the antenna effect.

14. A power outlet associated with a building power line network having a neutral line, a building ground line, and an earth ground that are connected one to another with a bus, the power outlet enabling a transmitter to impress a modulated carrier signal between the neutral line and the building ground line so as to transmit the modulated carrier signal to another location in the building power line network, the power outlet comprising:

a receptacle having at least a neutral contact and a ground contact;

a building ground line electrically coupled with the ground contact;

a neutral line electrically coupled with the neutral contact;

a conduit system including at least a conductive conduit containing at least a portion of the building ground line and the neutral line;

a first tuning element for applying a first tuning function between the building ground line and the conduit system, the first tuning function being selected to electrically isolate the building ground line from the earth ground when a carrier signal having a selected frequency is impressed between the neutral line and the building ground line; and

a second tuning element for applying a second tuning function between the neutral line and the conduit system, the second tuning function being selected to increase the capacitance between the neutral line and earth ground when the carrier signal having the selected frequency is impressed between the neutral line and the building ground line.

15. A power outlet as recited in claim 14, further comprising a conductive receptacle mounting frame associated with the receptacle, the conductive receptacle mounting frame being electrically coupled with the building ground line.

16. A power outlet as recited in claim 15, further comprising a transmitter having electrical contacts connected with the neutral contact and the ground contact of the receptacle, wherein the transmitter generates the modulated carrier signal and impresses the modulated carrier signal between the neutral line and the building ground line.

17. A power outlet as recited in claim 14, wherein the second tuning element comprises a capacitor positioned between the neutral line and the conduit system.

18. A power outlet as recited in claim 17, wherein the first tuning element comprises an inductor positioned between the building ground line and the conduit system.

19. A power outlet as recited in claim 17, wherein the first tuning element comprises a transformer positioned between the building ground line and the conduit system.

20. A power outlet as recited in claim 14, wherein the first tuning element applying the first tuning function and the second tuning element applying the second tuning function enhance one of a transmission line effect and an antenna effect.