1335 results about "Spectral density" patented technology

A spectral imaging system comprises a plurality of spectral units arranged in an array, each spectral unit of the plurality of spectral units comprising: a microlens having an optical axis; a spectral filter having a center wavelength and aligned with the optical axis; a fiber optic bundle, the fiber optic bundle having a curved light receiving surface and a planar light output surface, wherein the curved light receiving surface is aligned with the optical axis; and a plurality of pixel sensors configured to receive light from the planar light output surface of the fiber optic taper portion.

Various apparatus and associated methods involve a light source that provides light at wavelengths that substantially correlate to local maxima in the spectral sensitivity of a diurnal avian. In an illustrative example, the light source may output light primarily in wavelength bands that are not substantially absorbed by colored oil droplets and/or visual pigment in at least one type of cone in the eye of a diurnal avian. In some embodiments, the light source may include a light-emitting diode (LED) light source. Exemplary light sources may output spectral components to illuminate diurnal avians with local maxima of intensity at wavelengths that substantially correspond to local maxima in a spectral sensitivity visual response characteristic of the diurnal avians.

To alleviate the requirement to back-off all up-link performance, such as by limiting power spectral density, to overcome far-end cross-talk problems otherwise associated with relatively short loop-length wireline links, the present invention partitions the frequency spectrum based on an estimate of the loop length of a subscriber unit (CPE) modem from an exchange (LTE) modem. Up to a threshold frequency (fmax) at which received transmissions from a subscriber having a longest loop length (115) become indistinguishable by the LTE modem from a noise floor (102), up-link performance on all loop lengths is limited to correspond to that of the longest loop. At frequencies above the threshold frequency (fmax), subsets of subscribers (152-154) having relatively short loop lengths (116-119) use high frequency carriers that have signal to noise ratios sufficient to support information transmission in these elevated frequency bands.

A system abstracts channel information from field data gathered in actual wireless communication system environments. The abstracted data is then transformed into control signals or programming codes that can be used to control channel simulators so as to recreate the field conditions, including path loss, slow fading, fast fading, path delay, fading power spectral density with and without line-of-sight (LOS), and different kind of handoff scenarios, such as soft, softer, intra-band hard, inter-band hard handoffs. The system thus can accurately simulate a realistic wireless communication link originated from multiple signal sources in different band channels and formed by multipath signal propagation. The simulated realistic wireless communication link can be condensed by selecting the most useful scenarios from its original field data files or modified by tuning its parameters as desired.

The invention provides a method for enhancing microphone array voice based on combined inhibition. The method comprises the following steps of: structuring a microphone array for receiving external signals; analyzing the signals and obtaining time delays of different array signals relative to benchmark array signals in the microphone arrays opposite to a target voice source; respectively performing time delay compensation on digital signals corresponding to the two microphones, obtaining the compensated signals; respectively performing subband decomposition on the compensated array signals, and then forming fixed beams on each subband; meanwhile, respectively using blocking matrixes on each subband to obtain noise reference signals on each subband; and then respectively removing the noiseirrelative to the target voice form the fixed beam forming device on corresponding subband through an adaptive filtering processing algorithm, and then merging the subbands, thereby forming an initial gain signal; and meanwhile, making use of the previously compensated any two array signals to obtain a filter for inhibiting the noise signal related to the target voice through a recursive mutual power spectral density, thereby obtaining the final target voice signal through combining the initial gain signal.

A process variable transmitter with diagnostics based on power spectral density (PSD) analysis of a process variable sensor signal is provided. In one embodiment, the process variable transmitter is a pressure transmitter and the diagnostics are used to diagnose impulse line obstruction or impending obstruction. Other diagnostics are also useful such as diagnosing primary element degradation. The sensor signal is digitized and the digitized signal is transferred into the frequency domain. The power of the frequencies on the sensor signal is examined to provide the enhanced diagnostics. In one aspect diagnostics are generated directly with the sensor PSD data. In another aspect, the PSD analysis is used to tune a filter in order to enhance traditional diagnostic algorithms.

A technique for reducing interference between a direct-sequence ultra-wideband communications system and a narrowband communications system uses interference-rejecting spreading codes to reduce signal power in a frequency band associated with the narrowband communications system. A method of operating an ultra-wideband communications system includes applying an interference-rejecting spreading code to a signal for transmission. The interference-rejecting spreading code is configured to reduce power in a particular frequency band of a transmit or receive power spectral density associated with the ultra-wideband signal without substantially reducing power outside that particular frequency band of the transmit or receive power spectral density associated with the ultra-wideband signal.

The present invention provides a method and an apparatus may increase or extend the range of wireless communication cells for a given throughput in a downlink of a wireless communication system. When transmitting data in a downlink of a plurality of access point cells in a wireless local area network (WLAN), the range of the downlink may be increased for a given throughput under one or more radiated power constraints. The method includes providing a plurality of antennas at an access point to transmit the data to a wireless unit under at least one of a first and a second radiated power constraints. The method further includes using the plurality of antennas for bearnforming over a group of sub-carriers subject to the first and/or second radiated power constraints. Under one or more radiated power constraints, a multiple antenna based beamforming may extend the range of a wireless communication for a user of a wireless unit that may be located within a coverage area across the plurality of access point cells of a Wi-Fi network associated with the WLAN. A joint beamforming optimized over all of sub-carriers may account for a European regulation restriction into at least one of an averaged and a spectral density Equivalent Isotropic Radiated Power (EIRP) constraint. In this way, an Orthogonal Frequency-Division Multiplexing (OFDM) based joint beamformer may provide a significant performance improvement and range extension.

An apparatus and method for estimating the power spectral density of an unknown illuminant that does not require direct spectral measurements. The apparatus and method allows calibration of color images taken with commercially available digital cameras in arbitrary illumination. Besides an imaging system, a digital computer, a means for transferring image information from the imaging system to the digital computer, and software to carry out the method, the only additional equipment a photographer needs is a set of color standards.

Systems and methods of using machine-learning in a cognitive radio to avoid a jammer are described. Smoothed power spectral density is used to detect activity in a sub-band and basic characteristics of different signals therein extracted. If unable to classify the signals as either a valid signal or a jammer using the basic characteristics, ANN-based classification with cumulants features of the signals is used. Multiple periods are used to train sensing and communications (S/C) polices to track and avoid a jammer using RL (e.g. Q learning). The ANN has input neurons of higher order cumulants of a sensing channel and a single output neuron. The S/C polices are coupled during training and communication using negative or decreasing rewards based on the time the sensing policy takes to determine jammer presence and that the cognitive radio is jammed. A feedback channel provides a new communications channel to a radio transmitting to the cognitive radio.

A computing device-controlled system is described for the generation of amplitude-modulated pulse-width modulation (AMPWM) signals for use in treating neurological dysfunction via cranial neurostimulation, where the AMPWM signal is specifically designed to minimize the electrical impedance of the tissues of the head. A low-frequency carrier signal is determined for the AMPWM signal by measuring EEG activity at a reference site or sites, generally corresponding with the location of suspected brain dysfunction. Carrier signal frequency is variably related to critical frequency components of the EEG power spectral density, determined from statistical analysis of amplitudes and variability, and dynamically changed as a function of time to prevent entrainment. The AMPWM signal is presented to a subject via a plurality of neurostimulation delivery modes for therapeutic use.

For one aspect of the invention, a method is described for mitigating power spectral density irregularities in a multi-carrier modulation environment. The method involves identifying at least one carrier of a plurality of carriers that is in a non-data bearing state. Thereafter, that carrier is modulated with random data.

An apparatus for generating one or more audio output channel signals depending on two or more audio input channel signals is provided. Each of the two or more audio input channel signals comprises direct signal portions and ambient signal portions. The apparatus comprises a filter determination unit for determining a filter by estimating first power spectral density information and by estimating second power spectral density information. Moreover, the apparatus comprises a signal processor for generating the one or more audio output channel signals by applying the filter on the two or more audio input channel signals. The first power spectral density information indicates power spectral density information on the two or more audio input channel signals, and the second power spectral density information indicates power spectral density information on the ambient signal portions of the two or more audio input channel signals.