Appeal No. 1999-1449
Application 08/640,351
synchronized to the error values e(k) (52). There is no
reason to interpolate to generate the error values
synchronous to the channel rate.
In the present invention, the read signal 62 of FIG. 3
is sampled asynchronous to the baud rate. The asynchronous
samples 32 are processed by an interpolated timing recovery
circuit B100 to generate interpolated sample values B102
that are synchronous to the baud rate. As shown in FIG. 8B,
the synchronous sample values B102 are used to generate an
error value ek+t C104 that is also synchronous to the baud
rate. However, the coefficient update circuit C114 requires
the error values ek to be synchronous to the channel samples
Xk 25 rather than synchronous to the baud rate. Therefore,
as shown in FIG. 8B, the present invention provides an
interpolation circuit C106 for interpolating the baud rate
synchronous error values ek+t C104 to generate error values
ek C112 synchronous to the channel samples Xk 25. Again,
Nowak does not discloses or suggest this aspect of the
invention because in Nowak, the input sample values X(k)
(48) are synchronous to the baud rate and thus already
synchronous to the error values e(k) (52). Therefore, there
is no need to interpolate the error values e(k) (52) in
order to synchronous the error values e(k) to the channel
samples X(k) (48) as in the present invention. The same
argument applies to the alternative embodiment of the
present invention shown in FIG. 8C.
In order for us to decide the question of obviousness,
“[t]he first inquiry must be into exactly what the claims
define.” In re Wilder, 429 F.2d 447, 450, 166 USPQ 545, 548
(CCPA 1970). “Analysis begins with a key legal question-- what
is the invention claimed ?” . . . Claim interpretation . . .
will normally control the remainder of the decisional process.”
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