A dither-controlled automatic scan tracking system for television signal playback includes a field-store memory for storing a scan track control signal related to the average amplitude-tune "shape" of the transducer deflection control signal. The memorized scan track signal is added to a wideband scan track feedback signal to produce a composite signal which improves tracking error. Anomalous errors can result from memorizing signals which are systematic but unrelated to transducer or head deflection from the track. The errors are reduced by reversing the dither phase each television field, thereby allowing those signals unrelated to deflection to be identified and cancelled. The dither phase reversal can be switched or a continous phase progression.
In a magnetic recording reproduction apparatus, electro-mechanical transducing element supply voltage to maximize output read from a standard defining tape by a rotary magnetic head is stored in a memory disecretely corresponding to position of a head in the rotational direction per each mode such as still reproduction, slow reproduction or speed search, and the supply voltage corresponding to the position of the rotary magnetic head in the rotational direction is read from the memory during the use state, and the electro-mechanical transducing element is supplied with the supply voltage read from the memory and the position of the rotary magnetic head in the rotational axis direction is controlled.
It is difficult to read data from curved helical data tracks in a helical scan tape drive. Curved helical tracks can be caused by improper tape tension, tape damage, tape path misalignment, tape head offset between different head systems, and debris. The present invention solves the problem of recovering data from curved helical tracks by providing a table of different curve offset signals. Each curve offset signal represents a curve track profile of a typical curved track. The position of the helical read head reading a curved data track is controlled as a function of one of the curve offset signals such that the read head is positioned properly with respect to the helical data track to provide a proper read back signal. The curve offset signals are selected one at a time to control the position of the helical read head until the helical read head provides a proper read back signal.
A drive circuit apparatus for use in generating a drive signal for energizing an actuator about a natural resonant frequency is disclosed. The circuit has a counter that generates a count sequence derived from a drive sense signal. Additionally, a demodulator is further coupled to the counter and generates a voltage level signal from the drive sense signal based on the count sequence. A digital to analog (D/A) converter is coupled to both the counter and demodulator. The D/A converter generates the drive signal in a substantially constant phase relationship with respect to the drive sense signal as derived from the voltage level signal and based on the count sequence. In addition, a method of generating a drive signal for energizing an actuator about a natural resonant frequency is provided.
