Abstract: Receiver apparatus is provided for processing frequency hopped signals produced by frequency hopping or hybrid spread spectrum communication systems. A received frequency stepped carrier input signal is applied to dispersive delay lines connected in parallel branches and squaring circuits square the outputs of the dispersive delay lines. A comparator compares the outputs of the squaring circuits and produces an output related to the difference between the these outputs while an integrator integrates, over time, the comparator output and produces a corresponding output voltage signal. A voltage controlled oscillator connected to the output of the integrator produces an output signal whose frequency is related to the output voltage of the integrator. This signal is representative of the instantaneous frequency of the carrier input and can thus be used to demodulate the received signal.