Appeal No. 2006-1607
Application 10/062,894
BACKGROUND
Figures 1A-1D are said to illustrate "a conventional prior art digital pulse position
modulation (PPM) method where data is encoded by a pulse 120 located in one of four pulse
positions 110" (¶ 0023). "The four pulse positions 110 can also be viewed as being located in a
group of four slots. By changing the position of the pulse 120 within the group of slots over a
discrete span of time the data or information in the sample is transmitted." (¶ 0024-0025.)
"Referring again to FIGS. 1A-1D and FIG. 2, one group of four slots permits the transmission of
only binary bits of data when conventional PPM techniques are employed." (¶ 0030.) What is
described is "digital pulse position modulation," where a group of binary digits is represented by
a single pulse occurring in one of a series of time slots, as opposed to ordinary PPM where the
pulse can occur at any time within a range to represent an analog value. PPM may be
understood from the description of the prior art in Fig. 1 of Devon.
Appellant's invention has two aspects: (1) pulse code modulation (PCM) instead of PPM;
and (2) alternating phase encoding. In PCM, binary digits are represented by a time period
divided up into a group of time slots, where each time position of a slot may have either a pulse
(representing a binary "1") or no pulse (representing a binary "0"). The pulses within a time
period encode digital data. See W. David Gregg, Analog and Digital Communication (John
Wiley & Sons, Inc. 1977), p. 377, Fig. 11(a), (b). The digital data could represent an analog
signal or any digital data. PCM has been well known for a long time.
Pulses are normally shaped so that the skirt of a pulse is zero at multiples of the time
period Tmin so that the peak of a pulse being measured is unaffected by neighboring pulses,
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