Abstract: Radio Frequency Identification (RFID) readers with a directional coupler. At least one embodiment of the present invention provides an RFID reader designed to use a directional coupler to receive signals from an antenna which is connected to a radio frequency source of the reader to transmit signals. The directional coupler samples the signals received at the antenna and provides the received signal to a receiver of the RFID reader. In one example, the receiver of the RFID reader compares a portion of the signals from the radio frequency source with the received signal from the directional coupler to receive data from RF tags.

Abstract: An apparatus for object identification including a multi-meter terminal having a plurality of data modules, a triggering device for initiating one of the plurality of data modules to retrieve object identification data from an object, a radio module for downloading the retrieved object identification data to a host and a housing containing the data modules, triggering device and the radio module.

Abstract: A method and apparatus for object identification which includes a portable electronic tag reader having a transceiver capable both of reading identification information from electronic tags and transmitting collected information to a base unit for remote analysis. The system of the present invention utilizes the same transceiver to receive information from the base unit and write data to read/write electronic tags. The system of the present invention includes a transceiver for generating a modulated or unmodulated radio frequency interrogation signal, a receiver for detecting a return signal from an electronic tag and a signal processor for processing the return signal. A modulator within the portable unit combines the identification data with the radio frequency interrogation signal for transmission to a base unit through a wireless local area network. A demodulator within the portable unit extracts data and commands received from a base unit for local processing or transfer to a read/write electronic tag.

Abstract: The invention provides a reader-transponder system that prevents reading of undesired transponder signals. The reader generates a low-frequency signal that is used to supply power to the transponder. The same low-frequency signal also is used to generate a clock signal for the transponder. The reader varies the frequency of the low-frequency power signal according to a code that is unique to the reader. Because the transponder clock signal is derived from the encoded low-frequency power signal, it also varies in accordance with the reader's code. The coded transponder clock signal is contained in the modulation of the RF signal produced by the transponder. When the reader receives and decodes the RF signal, it also extracts the transponder clock signal from the received RF signal and compares variations in the extracted transponder clock signal to the code that was applied to the low-frequency power signal transmitted by the reader.

Abstract: A system for reading from and for writing data into electronic tags which may be associated with objects which are moving with respect to an interrogator, or may be located in fixed positions in the path of a moving interrogator. The interrogator, which is stationary if the tag is moving, sends a continuous RF signal to the remote tag. The tag backscatter-modulates the received RF signal with data temporarily or permanently stored in the tag, including, for example, data associated with the object to which the tag is attached, for example, its identity or contents. The system of this invention uses a very efficient encoding technique for the data which is backscatter-modulated by the tag and received by the interrogator. The backscatter-modulated signals are made up of signals of first and second frequencies f.sub.1 and 2f.sub.1, respectively, where the second frequency 2f.sub.1 is twice the first frequency f.sub.

Abstract: This invention relates to an improved signal reader for reading signals from transponders placed on moveable objects such as ship containers, automobiles or railroad cars. The reader sends out a continuous signal, which is modified by the information contained in the transponder attached to the moveable object. Multiple antennas, each of which receive separate signals, may be multiplexed at the reader. The improved circuit of the invention provides quick recognition of the receipt of a valid signal from a transponder or, in the alternative, the absence of such a valid signal.