A tracking system for optical storage media e.g. an optical disk, comprising a matrix (14) of four sensors (A, B, C, D) receiving a beam reflected by the disk; one processing channel for each sensor signal, including means (20, 21) for producing a binary signal from the sensor signal, and an adjustable edge delay circuit (23, 23') operating on the binary signal; one adder (25, 27) for each pair of channels corresponding to diagonal sensors of the matrix; and a phase detector (29) comparing the outputs of the adders.