A novel method for power line interference suppression

A novel method to suppress the power line interference induced into telephone lines that are in proximity to power conductors is proposed. A phase-locked loop is used to synchronize the interference signal with an anti-phase waveform, which is stored in a buffer. The anti-phase signal is injected on the line and the samples of the residual signal are used to update the anti-phase waveform. Computer simulations are used to compare the novel adaptive phase-locked buffer (APLB) approach with the traditional least mean squares (LMS) algorithm in an adaptive noise cancellation configuration. The new technique achieves 15 dB further suppression compared to LMS and since it can be implemented on a single digital signal processor (DSP) chip it proves to be a very efficient solution to the power line interference problem.