AC to DC converter for antiskid systems

摘要

A circuit for converting AC signals from a wheel speed transducer to a varying DC level indicative of the instantaneous rotational speed of the wheel of a vehicle. The invention includes a squaring circuit receiving a sinusoidal input from a wheel speed transducer and producing a fixed amplitude square wave of a frequency equivalent to that of the sinusoidal input. A pulsing circuit receives the square wave signal and produces a series of fixed duration pulses of a frequency double that of the sinusoidal signal. These pulses are applied to an integrator which produces a DC output of an amplitude characteristic of the frequency of the sinusoidal input. The integrator has a characteristic phase lag associated therewith resulting in a tendency of the phase of the superimposed AC output, caused by cyclic changes in the frequency of the transducer output, to lag the phase of the associated wheel speed change. A lead network is designed into the integrator to compensate for such phase lag and to cause the instantaneous amplitude of the DC output to more closely correlate with the associated change in wheel speed.