Excision of a discontinuous-frequency interference signal with harmonic structure

We consider the problem of excising a sinusoidal signal which is piecewise constant in frequency with random transition times, and which is duplicated at fixed frequency offsets. This signal interferes with a signal of interest. To remove this interfering signal, the most likely interfering frequencies at each point in time are estimated using a pair of sliding estimation windows obtained using compressed likelihood techniques, which account for all shifted versions of the interfering signals. This two-window approach avoids line broadening. The exact transition times are then estimated using median filtering, a sliding two-window scan of changes in frequency, and fine-tuning by comparison with the original signal. After identifying frequency transition times and the local interfering frequency, the interference is excised from the band of interest.