Receiver apparatus for three-phase power line carrier communications

• US 4,668,934 A
• Filed: 10/22/1984
• Issued: 05/26/1987
• Est. Priority Date: 10/22/1984
• Status: Expired due to Fees

• Current Assignee: ABB Power T&D Co Inc (ABB Limited)
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Shuey, Kenneth C.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Kuntz, Curtis
• Application Number:
  US06/663,251
• Time in Patent Office: 946 Days
• Field of Search: 340/310 A, 340/310 R, 340/870.03, 340/870.02, 340/825.01, 340/825.44
• US Class Current: 370/464
• 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 2203/5466 using three phases conductors
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5487 cables
• 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 transceiver is provided with both voltage and current coupling to a three phase transmission line system. Each phase conductor is coupled to a common point which is connected in signal communication with an input to a receiver. Another input of the receiver is coupled to the neutral conductor of the power line system by an H-field coupler. A signal coupling unit is associated with the voltage couplers between the common connection point and the first receiver input. The receiver is provided with the capability of comparing the voltage signal with the current signal and selecting the stronger of the two. Therefore, the transceiver of the present invention is less adversely affected by standing wave problems since the voltage and current signals are out of phase and voltage nodes are associated with current antinodes and vice versa. Therefore, regardless of the location along the standing wave that the transceiver is located, the best signal available will be used for demodulation purposes.

Claims

1. A transceiver for use with a three phase power line communication system, comprising:

a receiver having a first input connectable in signal communication with all three phases of said three phase power line and a second input connectable in signal communication with a neutral conductor of said three phase power line;

first means for coupling voltage signals from said three phases to said first input;

second means for coupling a current signal from said neutral conductor to said second input;

means for forming a first voltage signal from said voltage signals from said three phases, said forming means being connected in signal communication with said three phase power line and said first input;

means for selecting one of said first voltage signal and said current signal, said selecting means being connected in signal communication with said first and second inputs;

means for demodulating said selected signal, said demodulating means being connected in signal communication with said selected means; and

a transmitter having an output that is connectable in signal communication with said three phases of said power line.

2. The transceiver of claim 1, wherein:

said first coupling means comprises three capacitors, each of said three capacitors being operatively associated with one of said three phases of said power line.

3. The transceiver of claim 1, wherein:

said demodulator comprises a microprocessor.