The related detection is very classic. For a time series, by multiplying and summing it with a copy that slides, we search for the maximum value to determine the waveform’s burst position, completing the detection synchronization. This is a fundamental algorithm commonly used in the fields of communication and radar. In this issue, we utilize Matlab to dynamically simulate the correlation detection process using OFDM communication signals and LFM radar pulse signals. First, let’s look at the detection video of the real OFDM signal:In the video, the transmitted OFDM baseband signal consists of a synchronization segment waveform (marked in red) and a data segment waveform (marked in green). Simultaneously, the received baseband waveform without noise and the baseband waveform with added noise are plotted. During correlation, the synchronization segment waveform is used as a copy, sliding to the right along the time axis, extracting the corresponding waveform from the receiving end, multiplying and summing to calculate the correlation value. When it slides to the position where the OFDM signal appears, the correlation value suddenly increases, significantly higher than the nearby values, indicating a maximum value. By searching for the maximum value, we can confirm the burst position and complete the detection synchronization. Similarly, we continue to provide the detection video of the real LFM radar pulse signal:In the video, the transmitted baseband waveform consists of four LFM pulses, while the received baseband waveform without noise and the baseband waveform with added noise are also plotted. During correlation, one LFM pulse is used as a copy, sliding for correlation to calculate the correlation value. When it slides to the position where the LFM pulse appears, the correlation achieves a maximum value. By searching for the maximum value, we can confirm the burst position and complete the detection synchronization.The correlation detection process for real signals is relatively simple, but there is a significant issue: it is very sensitive to phase and can only be used on the basis of phase synchronization. Therefore, in practice, correlation detection is generally performed on complex signals, as correlation detection of complex signals is not sensitive to phase. We continue to provide the detection process video for OFDM and LFM complex signals:In the video, to visualize the complex signals, the real part and imaginary part of the complex signal are plotted on the y-axis and z-axis, respectively. The correlation detection process is consistent with that of real signals. Observant viewers may notice that the correlation detection operation is very similar to filtering operations, and indeed it is! Correlation detection is a special type of filtering, and its operations can be fully implemented using filtering.