Carrier transmission system utilizing commercial power lines as transmission lines

• US 3,909,618 A
• Filed: 01/18/1974
• Issued: 09/30/1975
• Est. Priority Date: 01/19/1973
• Status: Expired due to Term

• Current Assignee: Masaru Fujii, Tatsuhiro Yasunaga
• Original Assignee: Masaru Fujii, Tatsuhiro Yasunaga
• Inventors: Fujii, Masaru, Yasunaga, Tatsuhiro
• Primary Examiner(s): Schaffer, Robert K.
• Assistant Examiner(s): Ginsburg, M.
• Application Number:
  US05/434,832
• Time in Patent Office: 620 Days
• Field of Search: 307/3,27 340/31R,31A 179/2.5R,2.5A
• US Class Current: 307/3
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 2203/545 Audio/video application, e.g. interphone
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines

Abstract

A transmitter circuit and a receiver circuit couplied to such other via commericial A.C. power lines both include a phase locked loop (PLL) arrangement. In the PLL arrangement associated with the transmitter circuit, sound signals are applied to a voltage-controlled oscillator included therein to produce frequency-modulated carrier signals, which in turn are transmitted to the A.C. power lines. On the other hand, the PLL arrangement within the receiver accepts the frequency-modulated carrier signals transmitted via the A.C. power lines. Demodulation of the frequency-modulated carrier signals is provided by such PLL arrangement.

Claims

1. A frequency modulated carrier transmission system using commercial power lines comprising:

at least a pair of power lines;

a transmitter including a source of sound signals, a first voltage controlled oscillator means having a predetermined free-running center frequency driven by said source of sound signals to provide a frequency modulated carrier signal representative of said sound signals, amplifying and first matching means driven by said frequency modulated carrier signal for coupling the latter to said power lines; and

receiver means including second matching means coupling said receiver means to said power lines to receive said frequencymodulated carrier signal, a phase locked loop circuit including a second voltage controlled oscillator having a substantially identical free-running frequency as said first oscillator and driven by said Matching means to provide a demodulated output signal and a lock detection output signal, low frequency amplifier means receiving and amplifying said demodulated output signal in response to the existence of a said lock detection output signal to provide a driver output signal, and sound reproducing means responsive to said driver output signal.

2. The carrier transmission system defined in claim 1, wherein said receiver means and transmitter each include a power plug means connecting said first and second matching means to said power lines.

3. The carrier transmission system defined in claim 2, wherein said receiver means and said transmitter each include a power supply connected across said power plug means energized by said power lines and supplying operating bias to said receiver means and said transmitter.

4. The carrier transmission system defined in claim 2, wherein said receiver means further includes an electric instrument connected across said power plug means for energization by the power lines.

5. The carrier transmission system defined in claim 4, wherein said electric instrument comprises a housing for said receiver means.

6. A frequency-modulated carrier transmission system using commercial power lines comprising:

a pair of power lines;

transmitter means including an information signal source and modulator means responsive to information signals from said source for generating frequency-modulated signals, representative of the information contained in said signals, about a predetermined center carrier frequency and coupling said modulated signals with said power lines; and

receiver means coupled with said power lines and including a phase locked loop demodulator receiving and responsive to said modulated signals to provide a demodulated output signal and an output level signal indicative of the strength of the received signals, low frequency amplifier means, responsive to a predetermined minimum value of said output level signal for amplifying said demodulated output and output means driven by said low frequency amplifier means to reproduce said information.

7. The frequency-modulated carrier transmission system of claim 6, wherein said phase-locked loop demodulator includes:

first and second phase comparator circuits each having first and second inputs and an output receiving at their respective first inputs said frequency-modulated signals;

first and second low pass filter means driven, respectively, by said outputs of said first and second phase comparator circuits;

a voltage-controlled oscillator means with substantially the same free-running frequency as said center frequency having an input driven by said first low pass filter means and an output driving said second input of said first phase comparator circuit;

a 90* phase shift circuit having an input driven by said oscillator output and an output driving said second input of said second phase comparator circuit;

said first low-pass filter means providing a demodulated information signal at its output and said second low pass filter means providing a second demodulated information signal at its output; and

level detection means responsive to a predetermined minimum signal strength of said second demodulated information signal to generate said output level signal.