Abstract: An electronic device may be provided with control circuitry, wireless transceiver circuitry, and a display. The electronic device may be used to provide information to a user in response to being pointed at a particular object. The control circuitry may determine when the electronic device is pointed at a particular object using wireless control circuitry and/or motion sensor circuitry. In response to determining that the electronic device is pointed at a particular object, the control circuitry may take suitable action. This may include, for example, displaying information about an object when the electronic device is pointed at the object, displaying control icons for electronic equipment when the electronic device is pointed at the electronic equipment, and/or displaying a virtual object when the electronic device is pointed at real world object.

Abstract: A method for producing images of a subject with a MRI system is provided. A radio frequency (RF) excitation field in combination with a slice-select magnetic gradient field along a slice-select direction is provided. At least one readout magnetic field gradient is established along a frequency-encoding direction and at least one phase encoding magnetic field gradient along a phase-encoding direction. The RF field or magnetic field gradient is manipulated along a slice-select direction in order to impart a sequence of phase shifts to the formed echo signals such that image data corresponding to an at least one adjacent slice location is incoherently aliased across a field-of-view (FOV) of a current slice location. Image data is acquired indicative of the formed echo signals. A plurality of images of the subject is reconstructed.

Abstract: A method for imaging a substrate and product over time is provided. The substrate and product are magnetically tagged with at least one magnetic gradient where magnetically tagging provides a tag-dependent signal phase for the substrate and a different tag-dependent signal phase for the product. At least one readout of magnetically tagged substrate and product is provided over time. The tag-dependent signal phase is used to determine product that has been transformed from magnetically tagged substrate and substrate that has been transformed from magnetically tagged product over time.

Abstract: A method for producing images of a subject with a MRI system is provided. A radio frequency (RF) excitation field in combination with a slice-select magnetic gradient field along a slice-select direction is provided. At least one readout magnetic field gradient is established along a frequency-encoding direction and at least one phase encoding magnetic field gradient along a phase-encoding direction. The RF field or magnetic field gradient is manipulated along a slice-select direction in order to impart a sequence of phase shifts to the formed echo signals such that image data corresponding to an at least one adjacent slice location is incoherently aliased across a field-of-view (FOV) of a current slice location. Image data is acquired indicative of the formed echo signals. A plurality of images of the subject is reconstructed.

Abstract: A method for imaging a substrate and product over time is provided. The substrate and product are magnetically tagged with at least one magnetic gradient where magnetically tagging provides a tag-dependent signal phase for the substrate and a different tag-dependent signal phase for the product. At least one readout of magnetically tagged substrate and product is provided over time. The tag-dependent signal phase is used to determine product that has been transformed from magnetically tagged substrate and substrate that has been transformed from magnetically tagged product over time.

Abstract: A method for performing magnetic resonance spectroscopy is described. The method generally includes applying a tailored multiband spectral-spatial radio frequency excitation pulse to a sample including a first species and at least a second species having a different resonant frequency than the first species. The multiband excitation pulse excites the first species according to a first amplitude and excites the second species according to a second amplitude that is substantially greater than the first amplitude. Data is acquired from the sample. The acquired data is then utilized to generate a spectroscopic output. By way of example, the spectroscopic output is a spectroscopic image. In particular embodiments, the data for the first and second species is acquired dynamically over an observation window of time.

Abstract: A method for performing magnetic resonance spectroscopy is described. The method generally includes applying a tailored multiband spectral-spatial radio frequency excitation pulse to a sample including a first species and at least a second species having a different resonant frequency than the first species. The multiband excitation pulse excites the first species according to a first amplitude and excites the second species according to a second amplitude that is substantially greater than the first amplitude. Data is acquired from the sample. The acquired data is then utilized to generate a spectroscopic output. By way of example, the spectroscopic output is a spectroscopic image. In particular embodiments, the data for the first and second species is acquired dynamically over an observation window of time.

Abstract: Methods and apparatus for calculating spatial processing strategies in adaptive antenna array processing systems. Reference signal quality, intersymbol interference, data processed and received signal quality can be determined by burst type or remote device type and used to determine a synthetic signal level for use in developing a spatial processing strategy. A synthetic signal have an isotropically distributed component can be added to the antennas in the array or the diagonal elements of the received signal covariance matrix to develop uplink and downlink spatial processing strategies. Different synthetic signals at different signal levels can be used to develop different uplink and downlink spatial processing strategies. The downlink signal level can be larger than the uplink signal level. Uplink and downlink processing strategies can be developed in substantially the same way.

Abstract: A method and apparatus are provided that optimizes a transmitted user-specific signal. In one embodiment, the invention includes receiving signals from a remote radio, deriving estimates of receive channels corresponding to the received signals using the received signals, deriving a model of an expected transmit channel to the remote radio based on the receive channel estimates, deriving a set of transmit parameters to be applied to an array of transmit antennas to transmit a signal to the remote radio by optimizing a transmit power criteria using the model of the expected transmit channel and constraints on the estimated quality of a signal transmitted over the expected transmit channel, and transmitting to the remote radio by applying the derived set of transmit parameters to the transmit antenna array.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes collecting measurements of radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, collecting representations of the transmissions of the system user, and comparing the representations to the collected measurements to form a spatial characterization of the radio channel traversed by transmissions of the system user in which the elements of the spatial characterization represent forming a beam in the direction of the system user and directing nulls to interferers.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes collecting measurements of radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, collecting representations of the transmissions of the system user, cross-correlating the collected measurements and the collected representations, and comparing the cross-correlation to the collected measurements to form a characterization of the radio channel traversed by transmissions of the system user.

Abstract: Methods and apparatus for calculating spatial processing strategies in adaptive antenna array processing systems. Reference signal quality, intersymbol interference, data processed and received signal quality can be determined by burst type or remote device type and used to determine a synthetic signal level for use in developing a spatial processing strategy. A synthetic signal have an isotropically distributed component can be added to the antennas in the array or the diagonal elements of the received signal covariance matrix to develop uplink and downlink spatial processing strategies. Different synthetic signals at different signal levels can be used to develop different uplink and downlink spatial processing strategies. The downlink signal level can be larger than the uplink signal level. Uplink and downlink processing strategies can be developed in substantially the same way.

Abstract: An embodiment of the invention provides a method for effecting switchback on a spatial division multiple access (SDMA) PHS channel. A communication signal is broadcast over each of one or more SDMA channels of a multi-access channel to one or more corresponding user terminals. A set of transmit spatial weights is determined for a synchronization burst to a user terminal attempting to reestablish communication over an SDMA channel of the multi-access channel. The set of transmit spatial weights is determined such that interference caused by one or more communication signals to the synchronization burst is reduced.

Abstract: The present invention allows a radio receiver or a transmitter, with a plurality of antennas configured into an array, to be calibrated. In one embodiment, the method includes receiving a plurality of signals from a plurality of remote transmitters at the antenna array, sampling the signals received at at least two antennas of the array, computing a relative phase and amplitude of the sampled signals for each antenna, and computing calibration coefficients based on the relative phase and amplitude for the plurality of sampled signals from the plurality of remote transmitters for each antenna.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes measuring radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, accumulating the signal measurements into a first matrix, generating a second matrix representing the transmissions of the system user, cross-correlating the first and second matrices to form a third matrix, and multiplying the third matrix with a product of the second matrix to form a fourth matrix in which the elements of the fourth matrix characterize the radio channel traversed by transmissions of the system user.

Abstract: A method and apparatus are provided that can combine the benefits of beamforming with transmit diversity. In one embodiment, the invention includes sampling a signal received from a remote radio at elements of an antenna array, deriving spatial parameters for transmitting a signal to the remote radio from an antenna array, sampling the signal received from the remote radio at elements of at least one additional antenna array, and deriving spatial parameters for transmitting a signal to the remote radio from the at least one additional antenna array. The invention further includes generating diversity parameters for transmitting a signal to the remote radio using each antenna array as an element of a diversity array, and transmitting a signal to the remote radio using the spatial parameters and the diversity parameters.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes measuring radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, accumulating the signal measurements into a first matrix, generating a second matrix representing the transmissions of the system user, cross-correlating the first and second matrices to form a third matrix, and multiplying the third matrix with a product of the second matrix to form a fourth matrix in which the elements of the fourth matrix characterize the radio channel traversed by transmissions of the system user.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes collecting measurements of radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, collecting representations of the transmissions of the system user, cross-correlating the collected measurements and the collected representations, and comparing the cross-correlation to the collected measurements to form a characterization of the radio channel traversed by transmissions of the system user.

Abstract: A method and apparatus are provided that determine group delay for a set of transmit or receive chains over a wide frequency band without causing significant interference with simultaneous users of the system. In one embodiment, the invention includes an antenna array adapted to transmit and receive radio communications signals with a plurality of other terminals, the communications signals each using a particular minimum bandwidth, a transmit chain to transmit a calibration signal through the antenna array to a transponder on at least two different frequency bands within the minimum bandwidth, and a receive chain to receive through the antenna array a transponder signal from the transponder, the transponder signal being received on at least two different frequency bands and being based on the calibration signal. A signal processor determines a frequency dependent calibration vector based on the at least two frequency bands of the transponder signal as received through the receive chain.

Abstract: An embodiment of the invention provides a method for effecting switchback on a spatial division multiple access (SDMA) PHS channel. A communication signal is broadcast over each of one or more SDMA channels of a multi-access channel to one or more corresponding user terminals. A set of transmit spatial weights is determined for a synchronization burst to a user terminal attempting to reestablish communication over an SDMA channel of the multi-access channel. The set of transmit spatial weights is determined such that interference caused by one or more communication signals to the synchronization burst is reduced.