Note from Figure 1(c) that for this particular complementary pair the peak sidelobe ratio of the recurrent delay lobes is 20log10(8/52) = −16.25 dB. Selecting a reference containing only one complementary pair, namely only N (= 2) pulses, was done to simplify the drawings. Such a short CPI (CPI = 2 Tr ) yields insufficient Doppler resolution. When meaningful Doppler resolution is desired, N would usually be a large even number. As pointed out earlier in this introduction section, Doppler spoils the zero near-sidelobes property of complementary pairs waveform. How bad the degradation is, is the subject of the next section, which presents the delay-Doppler response (without a pulse canceller). DELAY-DOPPLER RESPONSE WITHOUT PULSE CANCELLER The signal used is a periodic train of N=64 pulses constructed from 32 identical complementary pairs with L =26 elements in each pulse. The element duration is tb implying a pulse duration tp = 26tb. In order to simplify the drawings the duty cycle is d = 0.2. This implies PRI (between individual pulses, not between pairs): Tr = 5tp = 130tb. The weight window preceding the DFT was DolphChebyshev with sidelobe level of -62 dB [in MATLAB terminology: chebwin(64,62)]. Figure 2 displays the delay-Doppler response of a matched filter processor without pulse canceller. The response is given in dB with a floor of -65 dB. The peak of the response, at the ori- Figure 1. (a) ACF of first coded pulse. (b) ACF of second coded pulse. (c) Periodic cross-correlation between the repeated pulse pair and a reference containing one pair. MARCH 2017 IEEE A&E SYSTEMS MAGAZINE 41