Abstract: A circuit which has two inputs at which respective ones of two time-displaced pulses may be received. The circuit also has an output at which a signal is produced if the pulses arrive in one order but not if they arrive in the opposite order. The circuit may have a second output at which a signal is produced if they arrive in said opposite order but not if they arrive in said one order. If spaced apart movement sensors are used to provide the two input signals, the circuit having two outputs indicates in which of two directions an object such as a vehicle passes the sensors. If only a single output is employed the circuit indicates each object passing in one direction but ignores objects passing in the opposite direction. Further applications of the circuit are disclosed.