Appeal Number: 2006-1385
Application Number: 10/452,753
Appellants assert (Br. 5) that neither Shridhara nor Beesley show a blanking
signal having a pattern similar to the jamming signal and synchronized with the
jamming signal. Appellants further argue (id.) that there is no reason to combine
Shridhara and Beesley. According to Appellants, “there is no need to generate a
variable amplitude/duration blanking signal as disclosed by Beesley, since
Shridhara teaches turning off the receiver or suppressing GPS readings or notifying
the user that the GPS position determination may be inaccurate in the presence of a
jamming signal” (id.). Additionally, Appellants assert that Beesley does not teach
a jamming signal having a known pattern due to the random nature of noise
generated by an ignition system (id.).
Accordingly, the issue before us is whether the combined teachings and
suggestions of Shridhara and Beesley would have taught or suggested to an artisan
a jamming signal having a known pattern and reducing the jamming signal with a
blanking signal having a pattern similar to the jamming signal and synchronized
with the jamming signal, as recited in claim 1.
From our review of the record, we find that Shridhara is directed to a method
for jamming detection and blanking for GPS receivers (col. 1, ll. 1-2). Shridhara
discloses detecting the presence of a jamming signal in the GPS receiver using any
one of several methods (Fig. 9). These methods include analyzing a rise in the
output from a correlator chain within the GPS unit (col. 4, ll. 34-36), determining if
clock drift is present without a corresponding increase in temperature (col. 4, ll.
46-48), detecting sudden changes in signal to noise ratio (col. 4, ll. 53-55), and
monitoring received signal strength to determine a sudden increase (col. 8, ll. 30-
31). Shridhara characterizes the jamming signal as noise that is generated from a
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