Patent
Dual frequency anti-theft system
TLDR
An anti-theft tag (34) containing a semiconductor diode (36) connected to a metal antenna loop (38) is configured to receive two distinct radio frequency transmissions.Abstract:
An anti-theft tag (34) containing a semiconductor diode (36) connected to a metal antenna loop (38) is configured to receive two distinct radio frequency transmissions. The diode (36) bridges a closed loop at one end of the antenna (38), forming a tank circuit resonant at twice a selected center frequency. A first transmitter (26) generates a tone modulated radio frequency (f) displaced on one side of the center frequency, and a second transmitter (30) generates a continuous wave radio frequency (f) displaced on the other side of the center frequency. Both signals are fed separately to respective dipole radiating antenna strips (18, 19, 20, 21) on opposite sides of a surveillance area. The dipole strips for the different frequencies are at right angles to each other on each side; those for the same frequency are at right angles to each other on opposite sides. This produces cross polarized transmission of both frequencies within the area. Diode (36) of tag (34) mixes the two frequencies received by the antenna loop (38), causing the tank circuit to resonate at the sum of the two frequencies (double the center frequency). That resonant frequency is reradiated to receiver antennae (22, 24) on each side for detection by a very narrow band receiver (42) responsive to the sum frequency. The modulating tone is derived from the received signal and processed to trigger an alarm (44) when the detected signal is of sufficient strength and duration.read more
Citations
More filters
Patent
Apparatus for energizing a remote station and related method
Marlin H. Mickle,Dmitry Gorodetsky,Leonid Mats,Lorenz Neureuter,Minhong Mi,Carl Taylor,Chad Emahizer +6 more
TL;DR: An apparatus for remote interaction with an object of interest includes a remote station for obtaining information from the object, a base station for transmitting energy in space to, communicating with the remote station, and a conversion means for energizing the remote base station responsive to the transmitted energy as discussed by the authors.
Patent
Method of manufacturing an enclosed transceiver
TL;DR: In this paper, a method of manufacturing an enclosed transceiver, such as a radio frequency identification (RFID) tag, is presented, where the tag comprises an integrated circuit (IC) chip, and an RF antenna mounted on a thin film substrate powered by a thin-film battery.
Patent
Method and apparatus for a wireless power supply
TL;DR: An apparatus for a wireless power supply including a mechanism for receiving a range of RF radiation across a collection of frequencies is described in this article. But it does not specify a power control scheme.
Patent
Electronic inventory label and security apparatus
TL;DR: A self-contained, reusable, electronic security label device and system wherein a tag device is attached to merchandise for the purpose of security, surveillance, pricing, tracking, accounting and inventory control is described in this article.
Patent
Electronic locating systems
TL;DR: In this paper, methods and apparatus for location of objects to facilitate retrieval, filing, security, inventory stock-keeping and the like are disclosed for the purpose of facilitating retrieval and filing of objects.
References
More filters
Patent
Electronic surveillance system
Peter H. Cole,Richard Vaughn +1 more
TL;DR: In this article, a passive label is attached to goods to be placed under surveillance and the label is interrogated by electromagnetic signals from a transmitter, the label acting to transmit a reply signal to a receiver which gives a characteristic response in the presence of a label.
Patent
Inductively coupled transmitter-responder arrangement
Thomas A Kriofsky,Leon M Kaplan +1 more
TL;DR: In this article, an inductively coupled interrogator-responder arrangement having two dimensional and limited three dimensional capability is presented, where the responder tag is completely passive, receiving its power from the AC power field generated by the interrogator.
Patent
Anti-shoplifting system
Fearon Edward R,Scarr Roger +1 more
TL;DR: In this paper, an electronic security system to detect the presence of an object which has had a label affixed thereto when said object passes through a surveillance zone comprising an oscillatory electromagnetic interrogation field having three separate and distinct vector components produced by driving the transmitting coils located in housings on either side of said surveillance zone with an alternating power source repetitively in and out of phase with respect to one another.
Patent
Electronic security system having improved noise discrimination
TL;DR: In this article, a multi-frequency resonant tag circuit with distinct frequencies for detection and discrimination was used in a controlled area such as a retail store and employing a multiuser tag circuit having distinct frequencies.
Book
Radiotron designer's handbook.
TL;DR: The high output voltage which must be delivered by the resistance-coupled penultimate stage thus shows its effect on the distortion, even though the plate supply voltage has been increased to a dangerously high value.