Conclusions

Frequency-domain methods can be used to attack unwanted sources in array data if we have an estimate of the signal of the unwanted source and if energy from this source is uncorrelated with that from other sources. If the interfering source is not too strong, a single-channel least squares method can do an effective job of removing the interfering source. For more difficult cases, I have demonstrated a multichannel method that looks promising. More work is needed to understand the theoretical basis of the multichannel method and to better understand when to use it.