Deep zeros in the spectrum of the input data? I wanted to know the meaning of "deep zeros" in the spectrum of the input data. I came across this terminology while going through the introduction of chapter 2 (Bussgang techniques for blind deconvolution and equalization) of the book named "Blind Deconvolution" by Simon Haykin.

Thanks,
JK
"Deep zeros" in the input spectrum are caused by a channel which strongly attenuates one or several frequencies, often due to multipath fading. This causes problems for a (linear) equalizer because it tries to compensate for these "deep zeros" by strong amplification of the corresponding frequency bands, which leads to noise enhancement. Non-linear equalizers are better at dealing with such problematic channel conditions.