A channelized cross spectral method for improved frequency resolution

A common problem in signal processing is the detection of weak tones in noise. Most tone recovery methods assume the presence of a single tone, or that the existing tones are sparse and well separated in frequency. In this paper, it is shown that tones may be detected and accurately estimated by first estimating a frequency error using the cross-spectral phase. The signal is then heterodyned by the error to translate it to the frequency of a Fourier basis element. The method has high gain, and may be used to isolate and recover tones which are not well separated.