Left: closed-loop repetition time and time delay in the loop as a function of target K magnitude. For stars fainter than K = 6, the loop repetition time is increased (i.e., its frequency decreased) to ensure a sufficient SNR on the detected fringes in each individual measurement (until the specified SNR cannot be reached any more whatever the integration time). Right: noise residuals at the output of the closed loop, for the three main contributors: fringe sensing (FSU), delay line (DL) and atmospheric noises.