slide 18

The cross-correlation starts with the last received signal and the first template signal. When using the chirped signal, the correlation between high and low-frequency signals is low. This is evident in the left figure. The correlation only increases when the signals are completely overlapped, as shown in the right figure. The output of the matched filter is narrow, a significant difference from the original test. The implementation of the cross-correlation starts with the last of the received signals and the first of the template signals. So, in the test of using the chirped signal, it computes the correlation between the high-frequency signal and the low-frequency signal. The correlation between two signals with different frequencies is low. You can observe it obviously in the left figure. The correlation only becomes higher when the received signal and the template signal are completely overlapped. You can look at the right figure. The output of the matched filter is pretty narrow. Compared to slide 15 about the original test, you can see the difference is huge.