Improved narrowband interference rejection using frequency domain DC offset compensation

Discrete frequency domain adaptive filtering is often used for the restoration of signals in the presence of interference. Often, this is achieved by an approximate Wiener filter implementation. Sometimes, a desired response signal is derived from the received signal and so may be itself, contaminated by interference. If an interferer is narrowband and approximately bin centred, it constitutes a DC offset within that bin. This can reduce the quality of a Wiener filter restoration of the signal, irrespective of whether the interference contaminates either the primary, reference, or both signals. However, the DC offset can be readily removed using a simple technique. We outline this technique and demonstrate the considerable performance improvement through examples.