From: jeremy.compton@stonebow.otago.ac.nz (Jeremy Compton) Subject: SNET: U S Patent: Identification system Date: Thu, 17 Sep 1998 01:35:51 +1200 To: snetnews@world.std.com -> SNETNEWS Mailing List United States Patent 5,041,826 Milheiser Aug. 20, 1991 Identification system Abstract A passive integrated transponder (PIT) is attached to or embedded in an item to be identified. It is excited via an inductive coupling from an interrogator. The PIT responds to the interrogator via the inductive coupling with a signal constituting a stream of data unique to the identified item. The signal is in the form of two different frequencies, a shift from one frequency to the second during a bit cell representing a data "one", and a shift from the second frequency to the first frequency representing a data "zero". The responsive signal is then detected and processed for utilization in a data storage or display device. Inventors: Milheiser; Thomas A. (Littleton, CO). Assignee: Destron/IDI Inc. (Boulder, CO). Appl. No.: 481,833 Filed: Feb. 16, 1990 Related U.S. Application Data Division of Ser No. 388,761, Aug. 2, 1989, abandoned, which is a continuation of Ser. No. 165,310, Mar. 8, 1988, abandoned, which is a division of Ser. No 814,492, Dec. 30, 1985, Pat. No. 4,730,188, which is a continuation-in-part of Ser. No. 580,401, Feb. 15, 1984, abandoned. Intl. Cl. : H04Q 1/00 Current U.S. Cl.: 340/825.54; 340/825.69; 375/272; 455/41 Field of Search: 340/825.54, 825.55, 825.69, 825.72, 825.34, 825.94, 572; 455/118, 41; 375/45, 62, 78, 81, 52; 370/53, 112 References Cited | [Referenced By] U.S. Patent Documents 3,109,143 Oct., 1963 Gluth 375/81 3,510,779 May, 1970 Klapper 375/81 3,689,885 Sept., 1972 Kaplan et al. 455/41 X 4,287,596 Sept., 1981 Chari 375/52 X 4,313,033 Jan., 1982 Walker et al. 370/112 X 4,368,439 Jan., 1983 Shibuya et al. 375/62 X 4,388,730 Jun., 1983 Nash et al. 375/81 X Primary Examiner: Weldon; Ulysses Attorney, Agent or Firm: Sirr; Francis A., Hancock; Earl C. 14 Claims, 8 Drawing Figures [USPTO] -> Send "subscribe snetnews " to majordomo@world.std.com -> Posted by: jeremy.compton@stonebow.otago.ac.nz (Jeremy Compton)