The present invention relates to a method and circuitry for determining a spreading factor in a communication system with variable data rates. In such a system the received signal may include a plurality of data symbols that are spread in the transmission signal in a manner that is defined by a spreading code and a spreading factor, the spreading factor being one of a plurality of possible spreading factors. In accordance with the method, the received signal is processed so as to produce signal outputs which are cleared from the effects of the spreading code, autocorrelation values are computed for the signal outputs, and the spreading factor is determined based on the computed autocorrelation values.