Kahn v. Dynamics Corporation of America

367 F. Supp. 63, 180 U.S.P.Q. (BNA) 247, 1973 U.S. Dist. LEXIS 11911
CourtDistrict Court, S.D. New York
DecidedSeptember 14, 1973
Docket69 Civ. 2783 (CHT)
StatusPublished
Cited by12 cases

This text of 367 F. Supp. 63 (Kahn v. Dynamics Corporation of America) is published on Counsel Stack Legal Research, covering District Court, S.D. New York primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Kahn v. Dynamics Corporation of America, 367 F. Supp. 63, 180 U.S.P.Q. (BNA) 247, 1973 U.S. Dist. LEXIS 11911 (S.D.N.Y. 1973).

Opinion

OPINION

TENNEY, District Judge.

This is a suit for the alleged infringement of U.S. Patent No. 3,030,503 granted to plaintiff Kahn, a resident of New York, on April 17, 1962 on a “continuation” of Kahn’s original application Serial No. 365,964, which was filed July 3, 1953 and abandoned December 13, 1960 after repeated rejections by the Patent Office. The subject matter of plaintiff’s patent is an alleged improvement in the field of diversity receiving systems in which two or more radio receivers are utilized in combination to overcome the effects of signal fading resulting in low or negligible signal reception in one or more of the receivers. Defendant, Dynamics Corporation of America (“Dynamics”), is a New York corporation, having its principal office in New York City. 1 Dynamics, through its Radio Engineering Laboratories (“REL”) has been a leading manufacturer and supplier of diversity radio receiving equipment. This court has jurisdiction of this action (28 U.S.C. § *66 1338 (1970)) and venue is properly laid in this district (28 U.S.C. § 1400 (1970)).

Kahn alleges that claims 15 and 16 of his patent 2 are infringed by the diversity receiving equipment designated as Series Nos. 2300, 2500 and 2600 made and sold commercially by Dynamics. 3 Dynamics contends, after trial of the issues herein to the court, (a) that Kahn has failed to meet his burden of proving infringement; (b) that the Kahn patent is invalid in view of the prior art; (c) that if Kahn’s claims (i. e., 15 and 16) could be construed as applicable to Dynamics’ diversity receiving systems, said claims would be invalid on the ground of late claiming; and (d) that the Kahn patent is unenforceable against Dynamics because of Kahn’s laches.

Before considering Dynamics’ defenses to the present action, it is necessary to consider briefly the alleged scope of the Kahn patent. Kahn asserts, in essence, that his patent covers all diversity radio receiving systems in which the outputs of the diversity receiving branches are combined linearly in phase by any circuit which causes their strengths, at the point of combining, to be proportional to the squares of the strengths of the signals picked up by the respective receiving antennas for said signals. Such a system is designed to overcome the problem known as fading. Radio signals, in traveling long distances from the transmitter to a receiver system, may take many paths. While they may, but rarely do, follow the earth’s curvature, usually they travel upward away from the earth and are refracted back to the earth by an ionized layer that exists above the earth (the ionosphere). They may be refracted back once, or they may travel back and forth between the earth and the ionosphere many times before they reach the receiver system.

As a result, the signals intercepted by the receiver system antennae may have traveled over widely different paths of unequal distances from the transmitter to the antennae. Since these signals are cyclical in nature, as are all radio frequency signals — i. e., they have crest, or positive and null, or negative portions— the crest of a signal traveling one path may arrive at the same time as the null of the signal traveling another path and, when combined, the positive and negative portions effect complete concellation of each other. Intermediate stages of the relationship of crest and null may result in a weakening of the combined signals or, fortuitously, a major enhancement of the crests arriving at the same time. This continuous variation from a full equivalent to possible cancellation results in the phenomenon known as fading.

Furthermore, radio signal information does not occupy a single frequency but *67 must include a band or range of frequencies, and each frequency is affected differently by the refractions from the ionosphere and the surface of the earth. Consequently, the band of frequencies received at one antenna over one path may not be of equal strength or signal level across the whole frequency band. This produces a fading effect known as selective fading. Kahn’s patent is directed to a diversity reception system for improving signal strength in relation to noise level in which two or more receivers are simultaneously employed to receive signals transmitted over substantial distances and in which, after linear amplification and demodulation, the signals are combined in phase according to the rule of the ratio of the square of the incoming signals; e. g., if the incoming signals have relative amplitude of three-to-two they will be combined in the ratio of nine-to-four. No claim is made, nor could it be, that Kahn invented diversity reception or even a diversity reception system in which signals are combined.

With regard to the issue of infringement we must recognize the fundamental principle that an invalid patent cannot be infringed. John Deere Company of Kansas City v. Graham, 333 F. 2d 529, 530 (8th Cir. 1964), aff'd, 383 U.S. 1, 86 S.Ct. 684, 15 L.Ed.2d 545 (1966). We must likewise recognize that a patent is presumed valid and the burden of establishing invalidity rests on the party asserting it. John Deere Company, supra, 333 F.2d at 530. However, the presumption of validity is re-buttable, and when substantial evidence attacking the validity of a patent is introduced, the question of whether the patent constitutes an invention is then for the court, and the presumption is weakened if applicable prior art was not considered by the Patent Office. John Deere Company, supra, 333 F.2d at 530. Accordingly, we look first to the prior art and then to such disclosures of the prior art as were made to the Patent Office.

As early as 1931, Peterson, Beverage and Moore (engineers with the Radio Corporation of America (“RCA”)) had successfully placed in operation a diversity receiving system for trans-Atlantic radiotelephone service which was used for many years for rebroadcasts of programs originating abroad. The RCA engineers described their system in the Proceedings of the Institute of Radio Engineers (“I.R.E.”). 4 This system *68 caused to be added together the detected signals, as received and amplified, with a common automatic gain control (“AGC”) (sometimes referred to as an automatic volume control (“AVC”)) resulting in ratio squaring of the signals. In accordance with the practice prevalent at that time, they used square-law detectors, which are special devices for withdrawing the modulation, or the audio wave, from the modulated wave.

In 1937, Friis and Feldman of Bell Telephone Laboratories (“BTL”) described, in a paper, 5 a three-branch diversity receiving system and explained, with mathematical proofs, the signal-to-noise improvement made available by ratio squaring, the combining system they used therein, and concluded that, theoretically, ratio squaring was the maximal combining ratio.

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Bluebook (online)
367 F. Supp. 63, 180 U.S.P.Q. (BNA) 247, 1973 U.S. Dist. LEXIS 11911, Counsel Stack Legal Research, https://law.counselstack.com/opinion/kahn-v-dynamics-corporation-of-america-nysd-1973.