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Parallel Filter Detection With Pulse-Width Discriminator

IP.com Disclosure Number: IPCOM000044614D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Gardner, HJ: AUTHOR [+2]

Abstract

The present detection circuit is used in a magnetic recording application. It features two separate filter paths with different filter functions in each path. Also, the filter in each path is followed by a pulse-width discriminator which takes advantage of the individual characteristics of each filter to enable accurate detection of signals containing large amounts of third harmonic distortion. Analog data from a magnetic recording head is amplified by preamplifier 10 and possibly has some filtering of the signal by filter 11. At this point, the analog data stream is divided into two paths which separately process the analog signal in parallel. The first path through filter 12, comparator 13, pulser 14, and delay 15 is the same as would exist in a normal detection design.

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Parallel Filter Detection With Pulse-Width Discriminator

The present detection circuit is used in a magnetic recording application. It features two separate filter paths with different filter functions in each path. Also, the filter in each path is followed by a pulse-width discriminator which takes advantage of the individual characteristics of each filter to enable accurate detection of signals containing large amounts of third harmonic distortion. Analog data from a magnetic recording head is amplified by preamplifier 10 and possibly has some filtering of the signal by filter 11. At this point, the analog data stream is divided into two paths which separately process the analog signal in parallel. The first path through filter 12, comparator 13, pulser 14, and delay 15 is the same as would exist in a normal detection design. Filter 12 has a bandwidth, which is wide, allowing third harmonic signals to pass but maintaining phase linearity and thus accurate time of zero crossings. This results in accurately timed pulses for each peak. This path may have some erroneous pulses due to waveform droop caused by third harmonic distortion combined with the differentiating nature of the filter. The second path through filter 16 and comparator 17 has a lower bandwidth which reduces the third harmonic. With the third harmonic reduced, the resulting output has no extraneous switching due to droop but may have timing inaccuracy due to the low bandwidth and phase nonlinearity...