Appeal No. 1998-1365 Page 11
Application No. 08/663,969
determines the alignment between the sample clock and the 1PPS
signal, the latter which serves as a reference clock signal.
Vanderspool not only teaches determining alignment
between a clock signal and a reference clock signal, but also
teaches determining the alignment by counting the number of
cycles of the clock signal occurring in a predetermined period
of time. The reference’s “phase comparator and offset
quantifier 717 measures the number of incoming clock cycles
difference from the rising edge of the 1PPS signal to the
rising edge of the sampled clock.” Col. 8, ll. 15-18. By
measuring the number of incoming clock cycles difference from
the rising edge of the 1PPS signal to the rising edge of the
sampled clock, Vanderspool counts a number of cycles of the
sampled clock occurring in a predetermined period of time.
In view of the aforementioned teachings, we are persuaded
that either Marshall or Vanderspool, in combination with the
prior art as a whole, teaches the claimed limitation of
“determining if ... said clock signal and said reference clock
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