A receiver comprising: one or more variable gain elements; an automatic gain control (AGC) for controlling a gain of one or more of the one or more the variable gain elements; and a frame detector configured to detect the presence of a frame in a signal received by the receiver and to output a signal to the AGC on detection of a data frame, wherein the AGC is configured to estimate a signal to noise ratio (SNR) of the received signal on receiving an input signal from the frame detector, to calculate a SNR margin between the estimated SNR and a target SNR and to adjust the gain of one or more of the one or more variable gain elements to maintain a positive SNR margin such that in the event of interference with the received signal the one or more variable gain elements do not saturate.