Appeal No. 2000-0519
Application 08/800,627
Vertical Blanking Interval (VBI) line of a commercial TV
broadcast, both VHF and UHF" (footnote omitted) (p. 45).
The signal was synchronously demodulated and the in-phase
and quadrature components recovered (p. 46). The components
were crosscorrelated against the PN sequence and a function
of the results was plotted (p. 46). "Multipath signals are
indicated by peaks in the crosscorrelations" (p. 46) along a
time axis (figures 3 and 4). Hershey discloses a bistatic
radar based on this example, i.e., Hershey "consider[s] some
of the key parameters of a TV-base bistatic radar using a PN
sequence in a single VBI line" (p. 47). The system includes
matched filters (p. 47; figure 7) and carries out distance
processing (the position of the target in three dimensional
space) using time difference of arrival (p. 46). Although
Doppler processing is not expressly discussed in Hershey,
one of ordinary skill in the art would have been motivated
to perform Doppler processing in Hershey in view of the
teachings in Griffiths.
Thus, both Hershey and Griffiths expressly teach using
a modified television signal with a repeating sequence (the
PN sequence and its copy on a VBI line in Hershey and the
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