US 4,290,090 AGranted

Apparatus for and method of noise-free detection of inter-feature pauses to control selective replay in tape recording/reproduction systems

AssigneeSoundesign Corporation

InventorsRyuji Yamamoto, Kiyotaka Ohsawa

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Abstract

Recorded features on a recording medium have inter-feature pauses which must be reliably detected in order to control the selective replay of the features. Certain noise signals located within an inter-feature pause complicate the detection of the latter. These noise signals include low-frequency signals which have high voltage levels at playback speed, and middle- and high-frequency signals which have high voltage levels at fast forward or rewind speed. These high voltage levels of the noise signals could be mistaken for audio signals. A signal-processing circuit filters the noise signals from the audio signals. A control circuit changes the impedance of the signal-processing circuit such that the signals are filtered according to a first predetermined filter characteristic when the recording medium advances at playback speed, and according to a different second predetermined filter characteristic when the recording medium advances at fast forward or rewind speed. The filter characteristics attenuate the high voltage levels of the noise signals to low voltage levels, thereby preventing the noise signals from being mistaken for audio signals at the playback or fast forward or rewind speeds.

Claims10

Dependent claims

In a recording/reproduction system for selectively replaying features recorded on a recording medium, and for advancing the recording medium at any one of a selected playback speed, fast forward speed and rewind speed,

an improved apparatus for reliably detecting interfeature pauses between features to control the selective replay of the recorded features, said apparatus including recording head sensor means operative for detecting
audio signals whose voltage amplitudes are above a predetermined voltage value to indicate the presence of features,
non-audio signals whose voltage amplitudes are below the predetermined voltage value to indicate the presence of inter-feature pauses, and
noise signals located within the inter-feature pauses and having voltage amplitudes above the predetermined voltage value at all advancement speeds of the recording medium, thereby resulting in apparatus malfunction in distinguishing between an inter-feature pause and a feature itself,
the improvement comprising:
(a) first signal-processing means for attenuating the noise signals to voltage amplitudes less than said predetermined voltage value in accordance with a first predetermined frequency response characteristic;
(b) second signal-processing means for attenuating the noise signals to voltage amplitudes less than said predetermined voltage value in accordance with a second predetermined frequency response characteristic;
and
(c) control means for selecting said first signal-processing means when the recording medium advances at playback speed, and for alternately selecting said second signal-processing means when the recording medium advances at fast forward or rewind speed to thereby eliminate the aforementioned apparatus malfunction.

6 more elements

an improved method of reliably detecting inter-feature pauses between features to control the selective replay of the recorded features, said improved method including the step of detecting
audio signals whose voltage amplitudes are above a predetermined voltage value to indicate the presence of features,
non-audio signals whose voltage amplitudes are below the predetermined voltage value to indicate the presence of inter-feature pauses, and
noise signals located within the inter-feature pauses and having voltage amplitudes above the predetermined voltage value at all advancement speeds of the recording medium, thereby resulting in system malfunction in distinguishing between an inter-feature pause and a feature itself,
the improved method comprising the steps of:
(a) attenuating the noise signals to voltage amplitudes less than said predetermined voltage value in accordance with a first predetermined frequency response characteristic;
(b) attenuating the noise signals to voltage amplitudes less than said predetermined voltage value in accordance with a second predetermined frequency response characteristic;
and
(c) selecting step (a) when the recording medium advances at playback speed, and alternately selecting step (b) when the recording medium advances at fast forward or rewind speed to thereby eliminate the aforementioned system malfunction.

6 more elements

Dependencies are inferred from the claim text.