Power line communication system utilizing a local oscillator

• US 4,538,136 A
• Filed: 03/30/1981
• Issued: 08/27/1985
• Est. Priority Date: 03/30/1981
• Status: Expired due to Term

• Current Assignee: Amtel Systems Corp.
• Original Assignee: Amtel Systems Corp.
• Inventors: Drabing, Richard B.
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/248,728
• Time in Patent Office: 1,611 Days
• Field of Search: 340/310 R, 340/310 A, 340/825.71, 340/825.58, 340/825.52, 340/825.53, 375/65, 331/1 A, 332/19, 332/16 R, 329/50, 329/122
• US Class Current: 375/306
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 2203/5441 Wireless systems or telephone
• CPC Class Codes: H04B 2203/545 Audio/video application, e.g. interphone
• CPC Class Codes: H04B 2203/5466 using three phases conductors
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence

Abstract

Disclosed is a power line transmission system which generates a narrow band multi-frequency shift keyed signal having a first predetermined frequency representing a first state of information (e.g., a "0") and a second predetermined frequency representing a second state of information (e.g., a "1"). The system includes a power line connected between a transmitter and a receiver and the FSK narrow band signal is transmitted from the transmitter over the power line to the receiver which recovers the transmitted information. The system provides improvement over noise problems present in a power line and in addition provides multi-channel capability.

Claims

1. In a communication system, a transmitter for generating a narrow band RF frequency shift keyed signal on a powerline including a first and a second frequency in each of a plurality of channels corresponding to a first and a second logical data bit from a source of data, respectively, comprising:

an oscillator having an output;

a phase detector having a first input coupled to said output of said oscillator, a second input and an output;

an operational amplifier having a first input coupled to said output of said detector, a second input and an output;

a first RC network coupled between said first input and said output of said amplifier;

a voltage controlled oscillator (VCO) having an input coupled to said output of said amplifier and an output;

a multi-channel select circuit having an input coupled to said output of said VCO, an output coupled to said second input of said detector and a data input for providing a plurality of channels;

a second RC network coupled to said second input of said amplifier;

first means for providing each of said data bits to said data input of said multi-channel select circuit; and

second means for providing each of said data bits to said second input of said amplifier and said second RC network for controlling the magnitude and speed of change in the frequency of the output of said VCO in response to said first and said second data bits whereby said output of said VCO undergoes smooth transitions between said first and said second frequencies in each of said channels.

2. A transmitter according to claim 1 wherein said second RC network comprises a first resistor and a capacitor coupled in parallel between said second input of said detector and a reference potential and said second means for providing comprises a second resistor, the magnitude of the change of the frequency of said output of said VCO in response to each bit of data from said source is a function of the ratio of the magnitudes of said first and said second resistors and the speed of the change in the magnitude of the frequency of said output of said VCO in response to each bit of data from said source is a function of the magnitude of said capacitor.