Appeal No. 1998-0220
Application No. 08/297,437
We find the teachings of Thompson to be representative of the well-known
advantages and tradeoffs with respect to the use of multiplexers in digital processing. We
further find that the artisan would have been motivated to replace the redundant circuitry as
shown in appellants’ prior art Figure 2 for the purpose of decreasing hardware
requirements, with full awareness of the tradeoffs associated with reduction in speed of
processing. The examiner, on page 6 of the Answer, explains how the artisan would have
found the particular refinements of the independent claims to be rendered obvious by the
knowledge of the prior art.
Appellants’ arguments on pages 22 through 24 of the Brief, concerning Thompson’s
lack of disclosing a “real-time” filter system, are not well taken. The arguments fail to take
into account the admitted prior art as represented by instant Figure 2. As admitted at the
bottom of page 23 of the Brief, prior art Figure 2 is directed to a parallel channel, “real-
time” filter system. Thompson teaches that in his invention speed of processing is a
concern, and indeed is improved over the prior art. See, for example, column 1, lines 28
through 32, wherein prior art software implementations were considered to lack speed and
efficiency. Appellants’ characterization of Thompson as disclosing a “sequential” filter is of
little import. Instant prior art Figure 2 also discloses filters which are effectively
“sequential,” since the outputs of filter 1 and filter 2 are selected one at a time by means of
multiplexer 72. Appellants’ invention, as shown in instant Figure 3, is in a similar sense
“sequential,” as the ultimate output is selected from one filter and then another. Moreover,
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