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Kustom Signals, Inc. v. Applied Concepts, Inc.

United States Court of Appeals for the Federal Circuit

September 5, 2001, Decided



 [***1136]   [*1328]  NEWMAN, Circuit Judge.

Kustom Signals, Inc. appeals the judgment of the United States District Court for the District of Kansas, granting summary judgment of noninfringement of United States Patent No. 5,528,246 issued June 19, 1996, entitled "Traffic Radar with Digital Signal Processing." We affirm the judgment of the district court. 1


Traffic radar equipment emits radio signals that bounce off target surfaces and return to a receiver that determines target speed upon measurement of various characteristics of the signals. If the radar equipment or the target is moving, the returning signals have a different frequency from the outgoing signals because of the Doppler effect, a shift in frequency proportional to the relative speed of the source and the target. Thus, to determine the speed of a target vehicle, traffic radar equipment measures the frequency shift and if necessary corrects for the speed of the radar source.

In addition to measurement of frequency, the amplitude (magnitude or strength) of the returning signal may indicate the size of the target, its distance, the angle of the surface that reflects the radar beam, and the material of which the object is made. In general, a stronger signal is received from larger or closer objects than from smaller objects or objects farther away.

Before the introduction of radar systems incorporating digital signal processing, most traffic radars were designed to respond to the strongest return signal and display the target speed calculated from that signal. [**3]  This could cause misleading readings when a slower target with a stronger signal (such as a large truck) obscured the response from a faster target with a weaker signal (a speeding car). The introduction of digital signal processing solved this problem by employing a mathematical technique known as Fast Fourier Transform, which allowed analysis of the return signals in greater depth. With digital processing, the returned analog signal may be transformed into a representation based on frequency (indicating target speed) or amplitude (indicating target size).

Digital systems were generally known at the time of the '246 invention; there was evidence at trial that the defendants had marketed a traffic radar wherein digital signal and Fast Fourier Transform processing were utilized to process and search Doppler radar returns for the strongest signal. Multi-mode analog radars that had the capacity to track either the strongest or fastest target were also known in the art.

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264 F.3d 1326 *; 2001 U.S. App. LEXIS 19615 **; 60 U.S.P.Q.2D (BNA) 1135 ***

KUSTOM SIGNALS, INC., Plaintiff-Appellant, v. APPLIED CONCEPTS, INC. and JOHN L. AKER, Defendants-Appellees.

Subsequent History:  [**1]  Rehearing Denied October 19, 2001, Reported at: 2001 U.S. App. LEXIS 24256. Certiorari Denied April 15, 2002, Reported at: 2002 U.S. LEXIS 2365.

Prior History: Appealed from: United States District Court for the District of Kansas. Judge Kathryn H. Vratil.

Disposition: AFFIRMED.


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Civil Procedure, Appeals, Standards of Review, De Novo Review, Patent Law, Infringement Actions, Claim Interpretation, General Overview, Specifications, Description Requirement, Doctrine of Equivalents, Fact & Law Issues, Judgments, Summary Judgment, Summary Judgment Review, Standards of Review