Appeal No. 1999-1935
Application No. 08/754,270
pattern signal and a finite impulse response filter converts the output of the switch into an
analog signal. Spectrum characteristics of the pre-set muting pattern signal are selected
to coincide with a plurality of stop-band frequencies of the filter and to include stop-band
frequencies below a cut-off frequency of ½ Fs of the filter.
Representative independent claim 5 is reproduced as follows:
5. A digital signal muting method for muting a digital signal digitized with at
least one bit using a muting command at a time of transmission of said
digital signal, comprising:
selecting a pre-set muting signal generated in response to said
muting command so that a spectrum distribution of said pre-set muting
signal coincides with a plurality of stop-band frequencies of a finite impulse
response filter configured for converting said digital signal into an analog
signal and to include stop-band frequencies below a cut-off frequency of ½
Fs of said finite impulse response filter, and
wherein said pre-set muting pattern signal is 96 HEX.
The examiner relies on the following references:
Ahamed 4,142,066 Feb. 27, 1979
Miyakoshi et al. (Miyakoshi) 4,812,815 Mar. 14, 1989
Nishio et al. (Nishio) 5,574,453 Nov. 12, 1996
In addition, the examiner relies on the preamble of the original claims, since
amended, as admitted prior art [APA].
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