Abstract: A PCM digital audio signal playback apparatus is provided for multiplying a PCM digital audio signal to n times the sampling rate, interpolating extra sampling points with zero signals, and spline-function interpolating with an FIR digital filter. Accordingly, a sound reproduced from the output audio signal of the apparatus will be more natural as compared with common high-cut filtering with a high-cut filter.

Abstract: A PCM digital audio signal playback apparatus is provided for extracting from the digital audio signal read out from a recording medium an original signal component ranging lower than 1/2 of its sampling frequency fs, producing a harmonic from the original signal component, extracting a harmonic component ranging higher than fs/2 from the harmonic, and adding the harmonic component to the original signal component. Accordingly, a high-frequency carrying signal, e.g. an impulse, is processed without causing ringings in the waveform response.

Abstract: A control circuit for a helical scan playback, in which a rotary head is moved transversely by a varying amount. The transverse movement can be either a multi-valued tracking position error correction signal or a saw-tooth waveform, effective during a location data strip, for compensating for the fast movement of the tape during a scan operation.

Abstract: In a waveform reshaping circuit for a digital signal which has become distorted, the threshold level is varied according to the codes of bits preceding each bit in a bit string forming data in the digital signal so that, even if coding interference takes place, a reshaped, undistorted digital signal outputted by the circuit is substantially the same in waveform as the original digital signal.

Abstract: A device for setting the start position for recording on a magnetic tape includes a leader tape detector, a signal detector for determining whether or not a prerecorded signal exists on the tape, and mechanisms for setting the recording start location at a position following the prerecorded data by a predetermined amount. The device also functions to automatically set the recording start position at a correct position on the reverse side of the tape if it is determined that the originally scanned side is fall.

Abstract: This invention relates to a magnetic recording and reproducing device in which automatic settings of optimum recording bias current, optimum recording level and optimum recording equalization characteristic are successively accomplished in this order. The settings of the optimum recording conditions are achieved with high accuracy within short period of time by a computer control using a microprocessor.

Abstract: A magnetic-tape sound recorder which features a computer-controlled adjusting device capable of automatically adjusting the recording signal level and the recording bias current depending upon the magnetic tape to be put to use on the sound recorder.

Abstract: A method and an apparatus for detecting and automatically setting optimum recording bias in a tape recorder in which first and second test signals of low and high audio frequencies, respectively, are alternately recorded on a recording medium. While these are being recorded, the recording bias applied to the recording medium is varied in a plurality of steps between upper and lower limits. The tape is then rewound and the reproduced first and second signals are compared to determine at which recording bias step the reproduced levels of the first and second signals are equal to one another. The recording bias for normal recording is then set in accordance with the bias level present at the selected step.

Abstract: A device for adjusting the frequency response characteristic of a magnetic sound recorder at relatively low and high frequencies, wherein the signal level of the recording signal to be supplied to the recording head of the recorder and the amount of compensation for the frequency response characteristic of the recording signal are adjusted by visual observation of a visible signal produced by one of electrically actuated light-emissive semiconductor elements which are to be selectively energized depending upon the relationship between the signal level of the playback signal and a reference signal which may be one of a plurality of predetermined reference signals or may be variable with the level of the recording signal.

Abstract: This invention relates to a magnetic recording and reproducing device in which automatic settings of optimum recording bias current, optimum recording level and optimum recording equalization characteristic are successively accomplished in this order. The settings of the optimum recording conditions are achieved with high accuracy within short period of time by a computer control using a microprocessor.