Bae Systems Information and Electronic Systems Integration Inc.

Lockheed Sanders, Inc.

Herrick Technology Labs Inc.

Herrick Technology Laboratories, Inc.

David L Herrick

Diane Grieselhuber Mills

Geoffrey S Edelson

Cory S Myers

Edmund L Chase

William F Matthews, Iii

A system and method comprising an RFID scanner, a reader or an interrogator for interrogating a transponder of a desired RFID tag to be interrogated; a transmission device for transmitting a desired carrier signal toward the RFID tag to be interrogated; a receiving device for receiving an RFID signal from the RFID tag to be interrogated; a processing device for removing the carrier signal from the RFID signal and thereby leaving an encoded data field of the RFID tag to be interrogated and processing the encoded data field for determining a start bit sequence of the encoded data field for at least one scan; and an averaging device for averaging the encoded data fields of at least two scans with one another and facilitate reading the encoded data field of the RFID tag to be interrogated.

Method and system for improving reading range of FDX RFID tags

Spatial bandwidth imaging of the interior spaces and elements of a structure by transmission of low frequency, continuous-wave, narrow band signal or signals through the structure, measurement of the electric and magnetic components of the received signal received by narrow band Doppler or focused synthetic aperture methods over a range of signal paths extending from the transmitter and through the structure, and imaging of the effects of the interior space on the electric and magnetic components of the received signal.

Spatial bandwidth imaging of structural interiors

Determining the direction of a direct arrival path between a receiver and a transmitter in a multipath environment by determining a transmitter heading relative to the receiver as proportional to a frequency offset of the direct path signal component relative to a multipath pedestal, an absolute velocity of the transmitter as proportional to a width of the multipath pedestal, a relative velocity between the transmitter and the receiver as proportional to a magnitude and a direction of doppler shift of the direct arrival component of the received signal relative to the doppler pedestal, and an amplitude of the multipath pedestal as proportional to a number and magnitude of scatterers in the multipath environment. The method is applied for continuous wave and modulated signals, for stationary and moving transmitters and for tracking and mapping transmitter paths.

Direction finding and mapping in multipath environments

A method and system begin at a random node of a trellis model having a set of at least two axes, wherein one axis corresponds to time and a second axis corresponds to frequency, a set of M states, corresponding to a set of all possible frequencies that may be transmitted by the system, and branches leaving each state, that terminate at allowable transmit frequencies for a next frequency hop. The number of branches leaving each state is dependent on the number of encoded bits per hop. Next, B bits of data are passed to a buffer, where B is the number of bits that will be transmitted per frequency hop. The method and system then combine the B bits of data with information for previously selected frequencies to select a current frequency, transmit the selected frequency, and feedback the currently selected frequency information to be used as previously selected frequency information when selecting a next frequency.

Soft-decision trellis-coded differential frequency-hopped spread spectrum (DFHSS)

A method and apparatus for minimizing multipath interference for commercial FM signals which use SCA secondary signals in QAM format that includes tracking the time series of phase measurements of a received stereo pilot signal for determining the proper phase reference for demodulation of QAM signals at the center of the time series. Phase measurements of the pilot signal are tracked over a predetermined tracking period. The phase measurement is used to support demodulation of the QAM signal. The SCA secondary signals in QAM format transmitted on commercial FM have minimal multipath interference and Doppler interference by movement of transmitter and receiver (vehicular).

Apparatus and method for minimizing multipath interference

The determination of the geographical location of a signal emitter by the coherent, time integrated measurement of received signal wavefront phase differences through a synthetic aperture and the reconstruction of the wavefront of the received signal. The location of an emitter is determined by coherently measuring the phase gradient of an emitted signal at measurement points across a measurement aperture. Each measured phase gradient is integrated to determine a vector having a direction from the measurement point to the signal emitter and an amplitude proportional to the received signal. A figure of merit is determined for each possible location of the signal emitter by integrating each vector with respect to a propagation path between the measurement point of the vector and the possible location of the signal emitter, and the location of the signal emitter is determined as the possible location of the signal emitter having the highest figure of merit. The measurement aperture is generated by motion of a receiving aperture along the path and the receiving aperture is generated as by synthetic aperture methods. The receiving aperture may be mounted on an airborne platform and a positional towed body.

System and method for single platform, synthetic aperture geo-location of emitters

An apparatus and method are described for direction finding the source of emf emissions including a monotone signal by detecting the phase changes of the monotone signal during movement relative to the source. A software embodiment measures the amount of phase change.

Apparatus and method for finding a signal emission source

A method for determining the time difference of arrival, tdoa, of signals from a cellular telephone, includes determining tdoas for a plurality of channels, averaging the tdoas from the channels, subtracting the average tdoa from the individual channel tdoas to determine residual channel tdoas and determining an overall residual tdoa from the residual channel tdoas. An apparatus and method for collecting cell phone transmission signals for performing tdoa calculations, includes receiving, digitizing and temporarily storing wideband transmission signals while monitoring a known reverse control channel for a predetermined cell phone number to be located, and permanently storing the delayed reverse control channel signal once the predetermined number is identified.

Apparatus and method for locating cellular telephones

The present invention relates to signal processors and processing, and more particularly to apparatus and method for sensing, detection and/or demodulation of frequency hopping signals.

Growing community of inventors

Mont Vernon, NH, United States of America

David L Herrick