Velocity control system for a data storage apparatus

A velocity control system, for controlling the velocity of a head assembly in a disc drive in moving from one position of said head assembly to a desired position, said system comprising:

• counting means for generating a distance value, said distance value being an integer number, representing the number of tracks between said one position and said desired position;
• memory means for storing a plurality of velocity values, a first velocity value corresponding to said distance value, a second velocity value corresponding to an integer number obtained by subtracting an integer of one from said distance value;
• integrator means for producing a signal corresponding to the movement of said assembly across one track;
• oscillating means for generating a plurality of signals, all having the same frequency;
• comparator means for comparing each of said plurality of signals from said oscillating means to the signal from said integrator means and for producing a plurality of pulses, with each pulse having two states;
• said memory means for generating a modulated velocity signal in response to each pulse, said modulated velocity signal being said first velocity value in response to one state of each pulse, and said modulated velocity signal being said second velocity value in response to the other state of each pulse;
• and
• digital to analogue conversion means for converting said modulated velocity signal to an analogue signal, whereby said analogue signal being used to control the velocity of said head assembly.