Deutsche Thomson-brandt Gmbh

Franz Bigge

Jurgen Kaaden

Dietmar Uhde

Paul A Gillot

A regulating circuit for controlling the speed of a rotating disc to provide a constant frequency signal from the disc includes a signal pickup device which moves radially along the disc and provides a velocity signal the frequency of which changes by a factor .DELTA.f as the position of the pickup device on the disc changes. A processor receives the velocity signal and produces a control signal in accordance with the factor .DELTA.f. A change-over switch provides a fine range voltage and a coarse range voltage which are used to control the speed of the disc in a fine range mode and a coarse range mode, respectively.

Regulating circuit as for controlling the speed of a motor

In a calibration operation mode of a magnetic tape recorder for helical track recording, employing the R-DAT standard, a first magnitude of a pilot signal reproduced in a first magnetic head from a pilot signal recorded in a center track with respect to the first magnetic head is obtained. A second magnitude of a pilot signal reproduced in a second magnetic head from a pilot signal recorded in a center track with respect to the second magnetic head is also obtained. A ratio between the first and second magnitudes is calculated and stored prior to normal playback mode of operation. During normal playback mode of operation, the stored ratio is used for normalizing a first difference signal, between crosstalk pilot signals that are reproduced in one of the first and second magnetic heads relative to a second difference signal, between crosstalk pilot signals that are reproduced in the other one of the first and second magnetic heads. The first and second difference signals are applied to a capstan motor for reducing a head-track misalignment error.

Head track alignment arrangement in a magnetic tape recorder

A digital signal, such as obtained during playback from a DAT machine, includes a first component containing e.g. the audio content and a second component containing error recognition code. A signal processor derives in accordance with the second component an error signal representative of errors in the digital signal. A microcomputer then calculates an error rate signal. The error rate signal may be visually displayed or the error rate signal may be applied to the pre-amplifier circuits in the playback transducer stage to minimize the errors.

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Villingen, Germany

Franz Bigge