A method for processing a signal envelope generated by demodulating a received signal that includes a train of pulses that is transmitted at a carrier frequency and is modulated at a given baud rate with data symbols in accordance with a predetermined communication protocol, which defines features of the modulated signal. The method includes measuring a duration of a selected feature in the signal envelope as defined by the communication protocol. The baud rate of the signal is estimated based on the measured duration without counting the pulses in the received signal. The data symbols are decoded by processing the signal envelope responsively to the estimated baud rate.