An apparatus recovers synchronous data samples from an asynchronously over-sampled stream of data samples derived from an input signal the spectral characteristic of which is subject to variation. The apparatus comprises an FIR filter having an input for receiving the asynchronously over-sampled stream of data samples and for producing equalised asynchronous samples. A signal sample reconstruction means reconstructs the synchronous data samples from the equalised asynchronous data samples. An automatic gain control loop is responsive to the reconstructed data samples to apply gain control for producing gain controlled reconstructed samples. A timing recovery means is responsive to the gain controlled reconstructed samples to provide timing information to the signal sample reconstruction means. A coefficient adaptation control loop is responsive to equalised reconstructed asynchronous data samples substantially unaffected by the automatic gain control for adapting the FIR filter coefficients to the variations in the spectral characteristics of the input signal.