Abstract: Apparatus for measuring the angular movement of a body comprises a tranducer for providing a signal the frequency f.sub.i of which is dependent on the angular velocity of the body and a reference frequency source providing a reference frequency f.sub.r. An (n + m) stage binary counter is provided for counting the number of reference pulses in time period 1/f.sub.i and an (n + m) stage binary store receives a count from said counter when the latter receives a signal from the transducer. The apparatus also includes an n-stage binary rate multiplier having a first input for receiving the n least significant figures of the store, and a second input for receiving an output signal from the apparatus, the rate multiplier being arranged to generate, during the period in which the rate multiplier receives 2.sup.n binary pulses at said second input, a number of output pulses which is equal to the number of pulses applied to said first input,.