Optimum impedance system for coupling transceiver to power line carrier network

• US 4,973,940 A
• Filed: 07/08/1987
• Issued: 11/27/1990
• Est. Priority Date: 07/08/1987
• Status: Expired due to Term

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Colin Electronics Co., Ltd.
• Inventors: Nishibayashi, Hideo, McGinnis, William H., Sakai, Hiroshi
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Lee, Benny T.
• Application Number:
  US07/071,641
• Time in Patent Office: 1,238 Days
• Field of Search: 333/101, 333/109, 333/124, 333/129, 333/131, 333/132, 340/310 R, 340/310 A, 455/78, 455/88, 455/5, 455/14, 375/7, 375/36
• US Class Current: 375/258
• 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 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

A method and apparatus for efficiently coupling a transceiver to an AC power line transmission system. The preferred embodiment of the coupling system comprises a line coupling network and first and second filter ports. The first filter port is connected to a resonant circuit having bandpass filtering characteristics adapted to the specific needs of the transmitter portion of the transceiver. The second filter port is isolated from the low impedance of the AC power line and is connected to a high quality factor filter having bandpath filtering characteristics adapted to the specific needs of the receiver portion of the transceiver.

Claims

1. An apparatus for coupling a transceiver to an AC power line, said transceiver comprising a transmitter portion for providing a first data signal to said AC power line and a receiver portion for receiving a second data signal from said AC power line, comprising:

a coupling circuit having first and second primary terminals and first and second secondary terminals, said primary terminals being electrically coupled to said power line, said secondary terminals being electrically coupled to said transceiver;

means for providing a first impedance between said first and second primary terminals and said first and second secondary terminals of said coupling circuit when said transceiver is transmitting said first data signal to said power line and means for providing a second impedance between said first and second primary terminals and said first and second secondary terminals of said coupling circuit when said transceiver is receiving said second data signal from said power line, said means for providing said first and second impedances each comprising at least one winding of a transformer electrically coupled to a means of switching, wherein said means for providing said first impedance, said means for providing said second impedance, at least one capacitor and one inductive element are arranged in a series connection between said first and second primary terminals of said coupling circuit; and

said means for switching connecting said means for providing said first impedance and said means for providing said second impedance to said first and second secondary terminals, respectively, wherein said means for switching is operable to switch respectively between said first and second impedances when said transceiver is transmitting and when said transceiver is receiving, wherein the optimum combined impedance between said first and second primary terminals is between one and ten ohms when said transceiver is switched to operate in said transmit mode and between 350 and 400 ohms when said means for switching is set to operate in said receive mode.

2. An apparatus according to claim 1, further comprising high impedance isolation means electrically connected between said secondary terminals and said receiver portion of said transceiver.

3. An apparatus according to claim 2, further comprising tunable filter means electrically connected between said high impedance isolation means and said receiver portion of said transceiver.

4. An apparatus for coupling a transceiver to an AC power line, said transceiver comprising a transmitter portion for providing a first data signal to said AC power line and a receiver portion for receiving a second data signal from said AC power line, comprising:

a first transformer having a primary winding and a secondary winding, said primary winding defining first and second primary terminals, said first primary terminal being electrically connected to said power line, said secondary winding defining first and second secondary terminals, said first and second secondary terminals of said first transformer being electrically connected to said receiver portion of said transceiver;

a tuning capacitor connected between said first and second secondary terminals of said first transformer;

a second transformer having a primary winding and a secondary winding, said primary winding defining first and second primary terminals, said first primary terminal of said second transformer being electrically connected to said second primary terminal of said first transformer and said second primary terminal being electrically coupled to said power line, said secondary winding defining first and second secondary terminals, said first and second secondary terminals of said second transformer being electrically connected to the transmitter portion of said transceiver;

at least one inductor in series connection with at least one capacitor comprising the electrical connection between said first primary terminal of said first transformer and said power line; and

switching means providing a switchable connection between said transmitter portion and said receiver portion and said secondary terminals of said first and second transformers, respectively, said switching means being disposed between said tuning capacitor and said second secondary terminal of said first transformer, said switching means operatively disconnecting said tuning capacitor and receiver portion from the first transformer during the time that said transmitter portion is connected to the second transformer, and said transceiver is transmitting said first data signal on said power line, said switching means operatively connecting said tuning capacitor and receiver portion to the first transformer while disconnecting the transmitter portion from the second transformer during the time that said receiver portion is receiving said second data signal from said AC power line.

5. An apparatus according to claim 4 further comprising high impedance isolation means as electrically connected between said secondary terminals of said first transformer and said receiver portion of said transceiver.

6. An apparatus according to claim 5, further comprising tunable filter means as electrically connected between said high impedance isolation means and said receiver portion of said transceiver.

7. An apparatus according to claim 6, the impedance between said first primary terminal of said first transformer and said second primary terminal of said second transformer being between one and ten ohms when said transceiver is switched to operate in said transmit mode and being between 350 and 400 ohms when switched to operate in said receive mode.