Tham khảo tài liệu 'radar technolog part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Wideband Noise Radar based in Phase Coded Sequences 47 Fig. 8. PSL SSL and ISL comparison for 2048-Golay and 4096-PRBS sequences. Fig. 9. PSL SSL and ISL comparison including ideal dynamic ranges. The figure also shows ISL level vs. Eb N0 ratio for PRBS and Golay sequences. It can be observed that the ISL level for PRBS sequence is almost 50dB larger than the ISL level for Golay case. Moreover as the Eb N0 ratio increases the ISL level difference between Golay and PRBS sequences decreases. Whereas as the Eb N0 ratio level is increased to 16dB the Golay case shows slightly larger ISL level than PRBS sequence. At this same point the PSL level is zero. It is produced when the AWGN power is larger than the sequence power so the noise masks the signal. In plots of Figure 9 we have included the ideal dynamic ranges corresponding to both codes. We can notice that the cross point between the DR and SSL lines for the Golay case is 3dB larger than for the PRBS case. 4. Estimation of improvement achieved by using Golay codes in noise radar A controlled experiment of propagation was conducted in order to estimate the improvement achieved in the estimation of channel parameters. Two signals one based in 48 Radar Technology PRBS and other resulting from Golay codes were generated with a general purpose pattern generator with chip period Tc 20 ns. The signals were generated with two different values of Eb N0 ratio which are 20dB and 5dB. Signals were captured with a digital oscilloscope. In order to reduce the effect of system noise one hundred captures are taken for each signal and then averaged. These measured signals were correlated off-line with a replica of the original one. The obtained impulse response was used to estimate the mean delay Tmean and rms delay Trms. Applying a Fourier transform to the averaged power-delay profile an estimation of the frequency correlation function and the coherence bandwidth CB were calculated. From each code Golay and PRBS six signals were .
