Acquisition of GNSS Signals with Secondary Code Figure 22. Timing diagram of the implementation of the post-FFT secondary code removal using a memory followed by a parallel circular correlation (Figure 9) with NS = 4. The processing time to compute K times the full correlation is NFFT + L + NFFT + L + K[NFFT(NS - 1) + NSNP)] = NP[K(3NS - 2) + 4] + NZ[K(NS - 1) + 2] + 2L. Figure 23. Timing diagram of the implementation of the post-FFT secondary code removal using a memory followed by an FFT-based circular correlation (Figure 10) with NS = 4. The processing time to compute K times the full correlation is NFFT + L + NFFT + L + K[NFFT(NS - 1) + N FFTSNP] + 2LS + NS = NP[K(4NS + NZ,S - 2) + 4] + NZ [K(NS - 1) + 2] + 2L + 2LS + NS. 62 IEEE A&E SYSTEMS MAGAZINE AUGUST 2017