Method and apparatus for the cancellation of interference in electrical systems

An improvement in a phase tracking system including a first phase-locked loop and a phase tracking circuit, the first phase-locked loop for providing a first output and a second output, the first output being demodulated from a carrier signal, the second output being a voltage-to-frequency conversion of the first output, the phase tracking circuit including an amplifier, and a second phase-locked loop, the second phase-locked loop in part for phase demodulation of the second output to provide a phase-detected second output, the second phase-locked loop including a summing circuit, the improvement comprising:

• a separation circuit coupled between the first phase-locked loop and the phase tracking circuit, the separation circuit including an isolation circuit and an integrator circuit, the separation circuit coupled to the first phase-locked loop for receiving the first output, the first output including interference voltage, the isolation circuit for isolating any message signal in the first output from the interference voltage, the isolation circuit for providing an approximation of any message signal and the interference voltage as separate outputs, the separation circuit for providing the approximation of any message signal to the summing circuit through the amplifier of the phase tracking circuit, the separation circuit for integrating with the integrator circuit the interference voltage from the isolation circuit to provide an integrated interference voltage;
• and
• a differencing circuit disposed in the second phase-locked loop of the phase tracking circuit, the differencing circuit coupled for receiving the phase-detected second output and the integrated interference voltage from the separation circuit.