Tape transport

An improvement in a capstanless magnetic tape transport for controlling the movement of the magnetic tape, said tape having a reference clock signal recorded thereon and a data signal simultaneously recorded thereon, a supply reel containing said magnetic tape, a take-up reel, said supply reel and take-up reels being coupled by magnetic tape connected therebetween for movement between said supply and take-up reels, means forming a pair of spaced hubs for supporting and turning each of said reels, a take-up variable speed motor connected to said take-up reel, a supply variable speed motor connected to said supply reel, said improvement comprising:

• a current drive amplifier connected to each of said supply and take-up motors for supplying driving power to each motor;
• a phase lock loop (PLL) servo means for controlling said take-up drive amplifier and including a PLL clock for generating a PLL clock signal;
• a first tape reference input means connected to said PLL servo means, said first reference input means for measuring the speed of movement of said tape between said supply and take-up reels, said PLL servo means being responsive to said first tape reference means and connected thereto, said first tape reference means linearly driving said PLL servo means from a start-up speed to a selected speed;
• a second tape reference input means connected to said PLL servo means for reading said reference clock signal recorded on said magnetic tape and for controlling said PLL servo means so that the speed of said tape from said supply reel to said take-up reel is controlled so that said PLL clock signal and said reference clock signal on said magnetic tape are synchronized;
• and
• tensioning means for providing a tape tension servo loop said tensioning means being responsive to said driving power supplied to said take-up and to said supply motors by said corresponding current drive amplifiers, and the output of said tensioning means connected to said supply reel drive amplifier whereby tension is supplied to said tape in response to a continuously varied speed during playback, and whereby said tape speed is continuously varied during playback to exactly cancel any speed variation which occurs during original recording.