Resolver with sequential frequency and phase correction

Apparatus for adjusting the speed of recording media moving past a playback device such that the frequency of a reference signal provided by the media is in synchronism with a master signal, comprising:

• a first frequency-to-voltage converter coupled to said playback device and responsive to said reference signal for generating a first voltage having a magnitude proportional to the frequency of said reference signal;
• a second frequency-to-voltage converter responsive to said master signal and generating a second voltage having a magnitude proportional to the frequency of said master signal;
• comparator means responsive to said first and second voltages for detecting the difference between said first and second voltages and for generating a difference signal corresponding to the difference therebetween;
• means for detecting when said difference signal is within a predetermined range and for inhibiting the operation of said comparator means when said difference signal is within the predetermined range;
• a storage device having first and second input means, said difference signal being coupled to said first input means, and means for detecting when said comparator is inhibited and for applying a voltage to said second input means when said comparator means is inhibited, said storage device storing a signal at its output having a magnitude proportional to the voltage which has been applied to said first and second input means;
• and
• a summing amplifier having a first input connected to the output of said storage device;
• the output of said summing amplifier being coupled to means for driving said recording media past said playback device at said adjusted speed.