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Optimal Time Domain Filters for Recording Channels

IP.com Disclosure Number: IPCOM000094803D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Fan, GJ: AUTHOR [+2]

Abstract

A digital magnetic tape recorder can be regarded as a band limited communication channel. For every transition recorded, a unit pulse is transmitted through such a channel. A pulse is obtained from the output which is usually spread out in time. At a high bit rate, the output pulses tend to crowd together and become an analogue waveform. As the recording resolution is better than that of the playback process, there exists a range of densities where the output waveform, although crowded, can be accurately constructed by superimposing unit pulse responses.

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Optimal Time Domain Filters for Recording Channels

A digital magnetic tape recorder can be regarded as a band limited communication channel. For every transition recorded, a unit pulse is transmitted through such a channel. A pulse is obtained from the output which is usually spread out in time. At a high bit rate, the output pulses tend to crowd together and become an analogue waveform. As the recording resolution is better than that of the playback process, there exists a range of densities where the output waveform, although crowded, can be accurately constructed by superimposing unit pulse responses.

The main advantages of the types of time-domain matched filters described here are that the amount of intersymbol interference can be minimized and the amount of noise amplification can be controlled. The filters have the configuration shown in drawing 1. The sampled output of the tape system a(t) is the input of a tapped delay line. The n-1 stage delay line has time delays equal to the separation of two adjacent samples. The signals at these taps are amplified with controlled gains before they are summed up to yield the output y(t).

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