Power line communication system utilizing a local oscillator

Claim 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.