An electrical signaling system is disclosed. A modulator is arranged to accept information and encode that information in an alternating signal containing repeated rising and falling edges, by way of the time between consecutive rising or consecutive falling edges. A transmission path transmits the signal from the modulator to a demodulator. The demodulator is arranged to detect a signal edge and store a record of the signal around that edge and compare a subsequent part of the signal with that record thereby to detect a like edge and detect the time difference between like edges.