University of Notre Dame Du Lac

Thomas G Pratt

Robert Daniel Kossler

Jeffrey George Mueller

Joseph Lawrence Loof

Scott C Morris

Eric Jesse

Benjamin Strycker

Farzad Talebi

Neil Dodson

Jun Chen

Methods and systems for sensing a physiological characteristic of a subject. At least one receiver antenna can be provided in proximity to a portion of the subject's body to obtain at least one receiver signal resulting from at least one transmitter signal that has propagated to the receiver antenna and has been reflected, diffracted, scattered, or transmitted by or through the portion of the subject's body. One or more coherent signal pairs can be formed. Then, amplitude and phase information of a plurality of frequency components for each signal pair can be determined. A set of comparison values can be determined for each signal pair by comparing respective frequency component phases and respective frequency component amplitudes of the signals. Physiological characteristics of the subject can then be determined from these comparison values.

Heart and lung monitoring with coherent signal dispersion

Devices and techniques for authenticating wireless communications are disclosed. In some embodiments, the techniques can be performed by a network access point that includes a receiver to receive a wireless signal from a remote device. The network access point can also include a processor to calculate polarization data for the wireless signal and to determine whether the polarization data includes at least one characteristic that corresponds to a characteristic of a stored authenticated polarization signature.

Security for wireless communications

Systems and methods for improving isolation between a cosite transmitter-receiver system. The transmitter may send a first plurality of transmit signals from multiple transmit ports. The first plurality of transmit signals may be related to one another by a first set of complex weights. The receiver may detect channel-impaired versions of the first plurality of transmit signals at one or more receive ports. The receiver may analyze channel-impaired versions of the first plurality of transmit signals to estimate channel state information. The transmitter may use the channel state information to determine a second set of complex weights which will reduce the power received at one or more ports of the receiver when applied to a second plurality of transmit signals. The second set of complex weights may vary with frequency.

Enhanced cosite transmitter-receiver isolation

A signal source association method and receiver. A receiver can be used to detect a plurality of signals transmitted from a plurality of transmission sources. The receiver can determine amplitude and phase information for a plurality of frequency components of each of the plurality of signals. The receiver can also determine a set of comparison values by comparing the respective amplitude and phase information from one or more pairs of the plurality of signals. Finally, the receiver can associate one of the signals with one of the plurality of transmission sources using the set of comparison values. The comparison values can comprise Stokes parameters and the one or more pairs of the plurality of signals can comprise a pair of orthogonally polarized signals or a pair of signals detected from spatially-separated antennas.

Use of coherent signal dispersion for signal source association

Methods and systems relating to topics in space-polarization modulated communications. The topics include: adaptive space-polarization modulated communications using channel state information at the transmitter; adaptive decision boundaries at the receiver; carrier frequency offset estimation for multi-carrier modulation schemes; transmission of analog images using polarization and coherence dispersion information; and reduction of peak-to-average power ratio in multi-carrier modulation schemes.

Space-polarization modulated communications

A multi-port transmitter can synthesize and send a first plurality of transmit signals having a separability characteristic which permits them to be differentiated from one another. A receiver can then detect one or more receiver signals which include one or more combinations of received versions of the first plurality of transmit signals. The receiver may use the separability characteristic to determine the received versions of the first plurality of transmit signals from the one or more receiver signals. Then, the receiver may determine an estimated signal corresponding to the estimated receiver response to a second plurality of virtual transmit signals which comprise a combination of the first plurality of transmit signals. Determining the estimated signal may include forming a combination of the received versions of the first plurality of transmit signals.

Linear combinations of transmit signals by a receiver

Systems and methods for analyzing a characteristic of a transmitter, a receiver, or a propagation channel are disclosed. At least one receiver signal resulting from at least one transmitter signal that has propagated through a propagation channel can be obtained. A first signal pair can be formed from a first receiver signal and a first transmitter signal, or from first and second receiver signals obtained from spatially-separated receiver antennas, or from first and second receiver signals which are attributable to different transmitter signals. Amplitude and phase information of a plurality of frequency components for each signal in the first signal pair can be determined. A set of comparison values for the first signal pair can be determined by comparing respective frequency component phases or respective frequency component amplitudes. A characteristic of the set of comparison values can then be analyzed.

Coherent signal analyzer

Systems and methods for monitoring rotating machinery are disclosed. Transmitter and receiver antennas can be provided with access to the rotating machinery. At least one receiver signal resulting from at least one transmitter signal that has propagated through a portion of the rotating machinery can be obtained. A first signal pair can be formed from a first receiver signal and a first transmitter signal, or from first and second receiver signals obtained from spatially-separated receiver antennas, or from first and second receiver signals which are attributable to different transmitter signals. Amplitude and phase information of a plurality of frequency components for each signal in the first signal pair can be determined. A set of comparison values for the first signal pair can be determined by comparing respective frequency component phases or respective frequency component amplitudes. A characteristic of the rotating machinery can then be analyzed using the comparison values.

Monitoring rotating machinery using radio frequency probes

A system and method for detection of complex sinusoidal signals. The method can include obtaining a set of complex-valued samples of one or more signals, in the presence of unknown noise, using a plurality of sensors. The presence of &#x3ba; candidate complex sinusoids can be assumed. Then, &#x3ba; candidate complex sinusoids in the set of complex-valued samples can be estimated. The method can include comparing a measurement of the energy of the &#x3ba; estimated candidate complex sinusoids with a threshold value. Based on the comparison, a determination can be made whether to assume a different number of candidate complex sinusoids and repeat the estimation and the comparison steps, or to specify the estimated &#x3ba; candidate complex sinusoids as detected complex sinusoids. The threshold value can be determined using a penalty value which reduces the probability of overestimating the number of complex sinusoids.

Method and apparatus for sinusoid detection

Systems and methods for performing energy efficient communication. A transceiver for use in a point-to-point packet-based communication link with packet erasures is described. The transceiver can include a data source to provide bits of data for transmission to a remote device. The transceiver can map the bits of data to symbols in a constellation according to a modulation scheme and can provide the symbols on one or more subcarriers. The transceiver can include co-located orthogonally polarized antenna elements or spatially separated antenna elements or both. The symbols can be transmitted in packets via one or more of the antenna elements. The transceiver can determine a metric of average transmit energy per bit successfully decoded, and not erased, at the remote device and can adjust transmission powers at the antenna elements to reduce the average transmit energy per successfully decoded and unerased bit.

Energy efficient communications

A system and method of identifying changes utilizing radio frequency polarization includes receiving a reflected and/or transmitted polarized radio frequency signal at a receiver, filtering, amplifying and conditioning the received signal, converting the received signal from an analog format to a digital format, processing the digital signal to elicit a polarization mode dispersion feature of the received signal, and comparing the polarization mode dispersion features to a known calibration to detect a change in a characteristic of the target object.

Growing community of inventors

Niles, MI, United States of America

Thomas G Pratt