1351 results about "Spectral density" patented technology

Reducing a power of a signal electromagnetically coupled from a PLC medium to a digital subscriber line (DSL) medium. The method involves transmitting a data signal over the PLC medium at a first average power level from one of a plurality of PLC transmitters coupled to the PLC medium, then measuring first noise associated with a first signal received at a DSL receiver coupled to the DSL communication medium caused at least in part by the data signal transmitted over the PLC medium at a second average power level from the one PLC transmitter, the second average power level different than the first average power level, followed by measuring second noise associated with a second signal received at the DSL receiver coupled to the DSL communication medium caused at least in part by the data signal transmission over the PLC medium at the second average power level. A transmit power spectral density (PSD) for the data signal transmitted by the one PLC transmitter over the PLC medium is then changed, based on a difference between the first noise and the second noise, such that the changed transmit PSD for the data signal transmitted by the one PLC transmitter over the PLC medium reduces the power of the signal electromagnetically coupled from the PLC medium to the DSL medium caused by the data signal transmission from the one PLC transmitter over the PLC medium.

A system and method for imaging a sample are provided. In particular, a first combination of light and a second combination of light are received, in which a first cross correlation function is associated with the first combination and a second cross correlation function is associated with the second combination. Each of the first and the second combinations includes a first portion of light which is received from a reference arrangement and a second portion of light which is received from the sample, and a first relative position of the sample associated with the first combination is different than a second relative position of the sample associated with the second combination. In an exemplary embodiment of the present invention, the first cross correlation function is transformed into a first complex cross spectral density and the second cross correlation function is transformed into a second complex cross spectral density. Moreover, a third complex cross spectral density can be determined which is approximately an average of the first complex cross spectral density and the second complex cross spectral density.

There is provided a method of determining a diagnostic measure of sleep apnea including the following steps: acquiring an electrocardiogram signal, calculating a set of RR intervals and electrocardiogram-derived respiratory signal from said electrocardiogram, and hence calculating a set of spectral and time-domain measurements over time periods including power spectral density, mean, and standard deviation. These measurements are processed by a classifier model which has been trained on a pre-existing data base of electrocardiogram signals to provide a probability of a specific time period containing apneic episodes or otherwise. These probabilities can be combined to form an overall diagnostic measure. The system also provides a system and apparatus for providing a diagnostic measure of sleep apnea.

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 beamforming 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.

A method for carrying out an idle handoff from a macrocell to a microcell (picocell) in a hierarchical cell structure includes the steps of: a) allocating different frequency assignments (FA) to the macrocell and the microcell in a same service band, to construct the hierarchical cell structure; b) transmitting cell structure information of neighboring base stations and pseudo noise (PN) code from base station to mobile station; c) checking whether the mobile station is in the hierarchical cell by using the cell structure information of neighboring base station; and d) checking whether a value of the pseudo noise (PN) code is greater than T_ADD and greater than Ec / Io of the macrocell by periodically searching the pseudo noise (PN) code of the microcell, to carry out an idle handoff to the microcell, wherein the T_ADD represents a value of base station pilot strength required for the base station of neighboring set to be included in a candidate set, the Ec represents an pilot energy accumulated during one pseudo noise (PN) chip period, and the Io represents a total power spectrum density within a reception bandwidth.

The present invention provides a method for monitoring long-term potentiation and long-term depression, comprising placing a subject in head down rest position and monitoring in real-time cerebral mean blood flow velocity using a transcranial Doppler device during psychophysiologic tasks. The method involves using Fourier analysis of mean blood flow velocity data to derive spectral density peaks of cortical and subcortical processes. The effect of head-down rest at different time intervals is seen as accentuation of the cortical peaks in long-term potentiation and attenuation of subcortical peaks in long-term depression. The effect of different interventions could be evaluated for research, diagnosis, rehabilitation and therapeutic use.

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.

A signal to interference-plus-noise power ratio (SINR) measurement method for wireless communications systems which employ orthogonal frequency division multiplexing (OFDM) for multicarrier data transmission is disclosed. Fast-Fourier transform (FFT)-based SINR measurements can be computed on frame-by-frame or greater interval for individual or groupings of subchannel signals. Given a known transmitted time-domain OFDM frame preamble, and the corresponding channel and interference-plus-noise (IPN) corrupted received time-domain frame preamble, the disclosed method first computes the power spectral densities of the received signal of interest and of a received unwanted interference-plus-noise signal. The FFT-computed power spectral densities are then used to compute average received signal and received IPN power measurements for specified individual or groupings of OFDM subchannel signals. The power measurements are then frame-averaged using a recursive exponential smoothing method. The frame-averaged signal and IPN power measurements are then used to form quantized measurements of SINR for the specified OFDM subchannel signals of the received frame.

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.

A system and method for producing and controlling a random signal with simultaneous control of both the power spectral density (PSD) and kurtosis (100) where a controlled signal is measured from a transducer, and converted to a PSD (111) using a Fast Fourier Transform (FFT). The measured PSD is compared (117) with a reference PSD (121) where an adaptive filter (119) is updated to compensate for the error. Simultaneously the kurtosis of the measured data is computed (125) and compared to a reference kurtosis (123). A feedback control loop (127) is employed to adjust the kurtosis of a white noise random generator with variable kurtosis (101). This white noise is then filtered by the adaptive filter (119) to provide the output signal used to drive the control process.

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.

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.

A method and system analyzes a telephone local loop and includes a central office operatively connected to the telephone local loop. A bandwidth analysis system is operatively connected to the central office and operative for determining the physical loop faults within the loop; qualifying the local loop for a particular Digital Subscriber Line (DSL) technology; and quantifying the local loop by calculating the transmit signal Power Spectral Densities (PSD) and calculating upstream and downstream data rates for particular DSL technology.

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.

The embodiment of the invention discloses a method and a device for suppressing residual echo, comprising the following steps: receiving a reconstruction voice echo signal y' obtained according to a far-end voice signal, and receiving an input signal e comprising a residual echo signal delta, wherein the input signal e is obtained by counteracting the reconstruction voice echo signal y' from a near-end voice signal d comprising a voice echo signal; transforming signals y', d and e into frequency domain signals Y '(omega), D (omega) and E (omega) through Fourier transform; calculating the power spectrum estimation Sy'y' (omega) of cross-spectral density Sed (omega) and Y'(omega) of D (omega) and E (omega), and calculating the noise signal power spectrum estimation Sww (omega); calculating the power spectrum estimation S delta delta (omega) of a residual echo signal delta according to an echo suppression capacity factor mu and Sy'y'(omega), wherein, mu is a controllable gain which is adjusted according to echo suppression capacity; and filtering the residual echo signal delta from the input signal e according to Sed (omega), Sww (omega) and S delta delta (omega). In another aspect, the invention also discloses relevant equipment. By adopting the method and the device of the invention, residual echo can be effectively filtered.

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.

A system and method for managing access to a satellite-based transponder by a plurality of aircraft each having a mobile radio frequency (RF) system. The system employs a ground-based, central control system for managing access to the satellite-based transponder so that the aggregate power spectral density (PSD) of the RF signals of all the mobile systems does not exceed, at any time, limits established by regulatory agencies to prevent interference between satellite systems. This is accomplished by a dual control loop arrangement for monitoring the signal-to-noise ratio (Eb / No) of the RF signal transmitted by the satellite-based transponder. A ground-based control loop is used whereby a ground-based central controller monitors the Eb / No and transmits commands to the aircraft (via the satellite transponder) to maintain the Eb / No of the transmitted signal within a predetermined range. A fast scan angle compensation is used by the mobile system of the aircraft to implement another control loop to further adjust the transmit power. This control loop maintains the Eb / No of the signal transmitted to the satellite-based transponder at the commanded level inbetween updates from the ground-based central controller.

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.

There is a provided a method for managing a multiple frequency assignment using a terminal's RX performance in an orthogonal frequency division multiple access (OFDMA) wireless regional area network (WRAN) system, including: a) measuring a bit energy / noise power spectral density (Eb / No) and a received signal strength indicator (RSSI) which are received in the terminal; b) informing the measured Eb / No and RSSI of a base station; c) calculating a round trip delay (RTD) in the base station; d) determining a terminal performance level based on the measured Eb / No, RSSI and the calculated RTD; and e) determining a frequency channel and modulation scheme based on the determined performance level.

A frequency domain method and system for online self-calibrating microphone frequency amplitude response based on noise floor (minima) tracking are disclosed. A cellular telephone or other system with dual microphones may self-calibrate itself on-the-fly. The system selects one of the microphones as a reference and calibrates the frequency response of the two microphones using the first microphone as a reference, so that they have a matched frequency amplitude response. To achieve this on-the-fly calibration, the system uses background noise for calibration purposes. The signal power spectra of the noise minima at the two microphones is used to calibrate the respective microphone frequency response. The system may then adapt the frequency amplitude responses of the two microphones so that the power spectral density from each microphone matches the other, and the system is then calibrated. This calibration could occur any time the device is receiving a noise minima and could be done continuously as the device is being used.

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.

New version devices of a home phone line network may operate on a first carrier frequency (within the new version frequency band) while old version devices may operate at a second carrier frequency (within the old version frequency band). Preamble, header, and trailer portions of a new version signal include a plurality of spectral copies of a baseband modulated signal. One or more of these spectral copies of the baseband modulated signal is / are indistinguishable from corresponding components of an old version signal. The new version signal is transmit filtered to have a negatively sloping power spectral density in order to maintain a constant power level in relation to old version signals and to have slope that is opposite of binder crosstalk so as to form, with the average crosstalk, a constant level white noise floor.