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Slow Speed Readout of Magnetic Recordings from Cyclic Memory

IP.com Disclosure Number: IPCOM000095798D
Original Publication Date: 1964-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kerby, HR: AUTHOR

Abstract

This system is for the slow speed readout of magnetically recorded information from a cyclic memory device, such as a disk or a drum, without mechanical speed change. A reproducing head is controlled to reproduce equally spaced samples of the recorded waveform during each cycle of the record medium. On each successive rotation cycle, the sampling interval is advanced with respect to the sampled waveform by one Nyquist sample interval, one-half the period of the highest frequency component present in the waveform. When the span between consecutive original samples has thus been read out, the recorded waveform can be completely and accurately reconstructed.

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Slow Speed Readout of Magnetic Recordings from Cyclic Memory

This system is for the slow speed readout of magnetically recorded information from a cyclic memory device, such as a disk or a drum, without mechanical speed change. A reproducing head is controlled to reproduce equally spaced samples of the recorded waveform during each cycle of the record medium. On each successive rotation cycle, the sampling interval is advanced with respect to the sampled waveform by one Nyquist sample interval, one-half the period of the highest frequency component present in the waveform. When the span between consecutive original samples has thus been read out, the recorded waveform can be completely and accurately reconstructed.

Using this technique, sufficient information can be obtained from the sampled waveform to completely reconstruct it. The rate at which sampling information is extracted for transmission or processing can be controlled by the number of samples taken during one cycle of the record medium and by its rotational speed.

This system is useful in applications where high speed recording and short access time characteristics of magnetic recording systems need to be coupled with the ability to read out recorded information more slowly. Some areas of application are in the (1) slow speed readout of stored documents for transmission over narrow-band communication facilities, (2) slow speed readout of wide-band analog instrumentation data, and (3) readout of stored...