Adaptive line enhancer (ALE) is an adaptive filter, it is a special type of adaptive noise cancellation (ANC) filter in which only one signal (noisy) is used to filter out the desired signal. As we known that the noise is uncorrelated to itself and ideally the auto correlation of noise is zero. The ALE filter the noise by correlating the noisy signal with its delayed version.
Shujaat Khan (2020). Auto/Adaptive Line Enchancement (ALE) using least mean square (LMS) algorithm (https://www.mathworks.com/matlabcentral/fileexchange/61764-auto-adaptive-line-enchancement-ale-using-least-mean-square-lms-algorithm), MATLAB Central File Exchange. Retrieved .