Abstract: A null-pilot symbol assisted fast automatic frequency control (AFC) system for coherent demodulation of carrier phase modulation (CPM) includes (209) a pilot clock driven phase differentiator (252,253,255) for operating once every pilot clock cycle to determine the difference between the phase at a current pilot symbol location and the phase at a previous pilot symbol location. A frequency offset selector (256) is then used for choosing the most likely frequency offset from amongst a set of all frequency offsets that give rise to the same phase difference.