Range sidelobe suppression in a desired Doppler interval

Sidelobe suppression in a desired range/doppler interval

“…In this section, we review the key results of [7]- [9] to lay a foundation for our new developments, which will be discussed in Section III. …”

“…The range sidelobes in the ambiguity function can cause masking of a weak target that is situated near a strong reflector. The reader is referred to [7]- [9] for more details and numerical results that show the sensitivity of Golay complementary waveforms to Doppler.…”

“…We have shown [7]- [9] that the spectrum of a binary sequence, called the Prouhet-Thue-Morse (PTM) sequence [17], [18], has a high-order null around zero and hence it suppresses range sidelobes along modest Doppler shifts.…”

“…Recently, we showed [7]- [9] that by proper sequencing of only two complementary waveforms across time it is possible to achieve an ambiguity response that is free of range sidelobes inside a desired Doppler interval. The complementary codes used are Golay complementary codes [10]- [12] invented Marcel Golay, which have the property that the sum of their autocorrelation functions is an impulse in delay.…”

“…The key idea is to view the PTM pulse trains of [7]- [9] as pulse amplitude modulation (PAM) waveforms and to exploit the time-frequency duality between PAM and orthogonal frequency division multiplexing (OFDM). The pulse trains reported in [7]- [9] are indeed PAM designs, and they are constructed by amplitude modulating a narrow pulse shape by a PTM sequence of Golay codes. Depending on the choice of the PTM sequence, the PAM waveform produces an impulse-like ambiguity response in delay (time shift) over a particular Doppler interval.…”