Appeal No. 97-1167 Page 8
Application No. 08/475,062
harmonic distortion of the reproduced signal.
Decision circuit 26 compares the second harmonic
distortion with a reference 28. Current driver 12
adjusts the bias current based on the output of
decision circuit 26. (Id.)
He concludes that it would have been obvious to combine
Ottesen with Admission “to provide dynamic control of a
reproducing head, to maintain it at an optimum operating point
....” (Id. at 5-6.)
The examiner admits that the combination of Admission in view
of Ottesen “lacks a circuit for measuring the signal to noise
ratio of the reproduced signal.” (Id. at 6.)
He notes that Shimotashiro “selects the bias current
value as an optimum value for maximizing an overall S/N ratio.
Adder 12 combines the S/N ratio resulting from noise with a
S/N ratio resulting from distortion. In this way,
Shimotashiro ... teach[es] combining noise and distortion
measurement to optimize bias current.” (Id.) The examiner
concludes that it would have been obvious to combine
Shimotashiro with Ottesen in view of Admission “to enable a
higher recording rate and increase efficiency ....” (Id.)
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Last modified: November 3, 2007