43 results about "Channel equalisation" patented technology

The invention concerns a filter bank receiver (FBMC) effecting a carrier frequency offset compensation in the frequency domain. The receiver comprises an FFT module extended by the overlap factor (610), a module (630) offsetting a predetermined number of subcarriers at the output of the FFT followed by a filter for reducing interference between subcarriers (640), the number of subcarriers and the coefficients of the interference reduction filter being determined from an estimation () of the frequency offset. The vector of samples thus obtained is then the subject of channel equalisation (650) before being filtered by a battery of analysis filters and spectrally de-spread (660). Finally, after spectral de-spreading, the vector of samples is demodulated by an OQAM demodulation (670) so as to recover the transmitted data.

A method and circuit for performing channel equalisation in a high speed transmission system comprising a transmitter and receiver. An application specific digital signal processor, ASDSP, performs channel equalisation and compensation on digital data received from an analogue-to digital converter of the receiver. The ASDSP is operable to execute an application specific set of op-codes needed for performing channel equalisation and compensation. An ASDSP register is coupled between the ASDSP and a system CPU in a feedback loop for performing channel equalisation at the receiver. The ASDSP stores equalizer parameters and bit error rate measurements used by the ASDSP for performing channel equalisation and compensation. An ASDSP program storage memory, coupled to and accessible by the ASDSP, stores an ASDSP micro-sequence program for controlling the processing steps for channel equalisation and dataflow through the ASDSP.

A method of reducing multiple access interference in a CDMA radio system uses a plurality of rake fingers to pre-process received signals but without demodulation or de-spreading. The outputs of the rake fingers are combined, normalised and then processed by an adaptive equaliser to recover orthogonality lost in transmission. The equaliser output is then subject to de-spreading and de-scrambling to recover the desired user signals. The equaliser is preferably adaptive order, the length being adapted in dependence upon the instantaneous signal to noise ratio.

Provided is a read channel incorporated in a storage device to process signals read from a storage medium. The read channel includes an equalizer equalizing input read signals to produce equalizer output signals. A detector senses an adjusted equalizer output signal to determine an output value comprising data represented by the input read signals. An equalizer adaptor receives the output value from the detector to determine a first error signal used to adjust the equalizer operations. A component adjusts the equalizer output signals being transmitted to the detector, wherein the component is adjusted by a second error signal calculated from the output value from the detector, wherein the first and second error signals are different.

The invention discloses a communication system, a communication method, a multichannel adaptive equalizer and an OFDM (orthogonal frequency division multiplexing) signal demultiplexing method. The OFDM signal demultiplexing method includes the steps: receiving OFDM optical signals multiplexed by N-channel optical subcarrier waves, demodulating the OFDM optical signals by respectively using series intrinsic light different in angular frequency so as to obtain corresponding OFDM electrical signals; and after adjacent frequency band signals except for baseband signals are subjected to attenuation of a low-pass filter, sampling the OFDM electrical signals in each channel so as to obtain corresponding OFDM electrical signal sampling values, and then reducing data carried by the corresponding optical subcarrier waves in each channel by using a multichannel balance matrix to multiply by the N-channel OFDM electrical signal sampling values. The OFDM signal demultiplexing method has the advantages that a receiving end does not require strict match of sampling time of signal demodulation in each channel, sampling rate is determined by modulating signal rate carried by single optical carrier wave, ADC (analog-to-digital converter) bottleneck restriction can be bypassed, and the method is applicable to the high-speed optical communication system.

An emitter converts a serial input data stream into a set of parallel substreams. An OQAM modulator (120) receives and supplies each substream to an input of a synthesis filter bank (130). Synchronization input(s) of the filter bank receive an OQAM signal that carries a data sequence. This sequence contains frame, superframe and hyperframe synchronization patterns, and specifies the number of bits allocated to each subchannel. A receiver (200) includes an analysis filter bank (210) that decomposes the multicarrier signal into a set of elementary signals for each subchannel. A synchronizing processing block (270) receives output(s) of the filter bank for synchronization subchannel(s). The block (270) includes a first cascade of blocks that control receiver sampling times, and a second cascade of blocks that extract synchronization patterns and subchannel bit assignment data. Other filter bank outputs are each coupled to a cascade subchannel equalizer (220) followed by a data extractor (230) and a parallel-to-serial converter (240).

The invention discloses a signal processing method based on a low-cost security radar. The method comprises the following steps: carrying out channel equalization on all signal channels of a digital array radar; transmitting digital beam forming and receiving digital beam forming; performing frequency domain pulse compression processing on the received signal; carrying out large-point multi-pulseaccumulation by adopting a moving target detection method; and carrying out target detection by adopting a maximum selection constant false alarm detection method to obtain a target trace point. According to the method, the algorithm of the low-power security radar is low in cost, a complete radar signal processing flow is realized on the low-power radar, the accuracy is high, the operation stepsare simple, the real-time performance is good, and the operation cost of low-power radar signal processing is reduced.

A method and system for detecting a VSB mode in a digital TV receiver is disclosed. The system includes first and second VSB mode detectors implemented before and after a channel equalizer. The first VSB mode detector detects a VSB mode from a signal before channel-equalization, the second VSB mode detector detects a VSB mode from a channel-equalized signal, and one of the detected VSB modes is output to the channel equalizer as the finally detected VSB mode.

The invention belongs to the array signal technology, and relates to a method of equalizing unmatched channels in a certain bandwidth. The channel equalization method comprises the following steps: 1, a frequency domain equalization filter is converted into an N-point filter, and N is selected to be the least power no smaller than L, and the N-point frequency feature e<N><O> of the frequency domain equalization filter is solved; 2, each section filter coefficient for segmented equalization is solved; and 3, the eN is used for carrying out equalization processing on a baseband complex signal xA of the to-be-equalized channel, and a complex signal sequence xAE after equalization is obtained. The storage space needed by channel equalization can be reduced, the cancellation performance between channels is improved, the array processing performance is thus enhanced, and requirements of multichannel array signal processing by a modern communication system, a phased array radar system and the like can be met.

Systems and methods of monitoring changes in an environment by means of one or more communication devices within the environment are provided, in which each of the communication devices is configured to receive a wireless communication signal transmitted from a source. In a method conducted by a central computing device, device data including channel equalisation information is received from each communication device, the channel equalisation information having being determined by the device performing channel equalisation on a wireless communication signal received by the communication device. The received device data is used to generate an estimate of the environment and changes in the generated estimate of the environment over time are recorded so as to monitor changes in the environment.

A new method of designing digital filters for specific magnitude and phase requirements that minimises the filter's group-delay given arbitrary error tolerances is presented in this patent application. The method is extended to include optimising the original filter design based on the group-delay minimisation routine. A particular example that describes the linearisation of a filter channel under these conditions and given these constraints is shown. Embodiments may be applied to any digital filter design technique implemented in software, hardware, or a combination of both for applications such as equalisation or any area where filters are useful. The method disclosed is broadly applicable in the field of signal processing and may be used to advantage, for example in: channel equalisation, speaker and audio correction, echo-cancellation, control applications, digital audio broadcast, sonar and ultrasonics.

A receiver for CDMA signals, in which data intended for transmission to multiple intended receivers is spread by respective orthogonal spreading codes and scrambled by an aperiodic random scrambling code, includes a processing branch for each of a number of base stations from which the receiver may pick up CDMA signals. Each processing branch performs both channel equalisation based on a set of weights for that branch, and a decoding operation. The outputs of the branches are combined to produce a combined signal which is used both for determining the data intended for the receiver, and in a feedback loop to improve the sets of weights. The receiver is reliable even in the presence of mutipath fading and during soft handover.

A method of reducing multiple access interference in a CDMA radio system uses a plurality of rake fingers to pre-process received signals but without demodulation or de-spreading. The outputs of the rake fingers are combined, normalised and then processed by an adaptive equaliser to recover orthogonality lost in transmission. The equaliser output is then subject to de-spreading and de-scrambling to recover the desired user signals. The equaliser is preferably adaptive order, the length being adapted in dependence upon the instantaneous signal to noise ratio.

The present invention relates to a method and also a device for digitally processing OFDM signals which are emitted by a transmission apparatus with modulation symbols as information carriers, reflected at one or a plurality of objects at least to some extent and received by a receiving apparatus. The modulation symbols are extracted without prior channel equalisation from the OFDM signals received and the extracted modulation symbols are normalised by a complex division to the respectively transmitted modulation symbol. The radar analysis for determining the distance and / or determining the speed of the objects then takes place on the basis of the normalised modulation symbols. With the method and the device, on the one hand, both distance and speed of the objects can be determined independently of one another. On the other hand, the method works very reliably, as it is not influenced by the transmitted information.

The invention discloses an underwater image enhancement method combining multi-channel equalization and multi-scale fusion, and belongs to the field of underwater image enhancement, and the underwater image enhancement method combining multi-channel equalization and multi-scale fusion is realized by the following steps: step 1, performing multi-scale image enhancement; compensating the red channel by using the green channel and secondarily reinforcing the red channel through the mean value of the regional red channel; step 2, using a self-adaptive platform histogram to extend the gray scale range of the R, G and B three channels in a balanced manner and redistributing gray scale values; and step 3, carrying out multi-scale fusion on the brightness V (Value) components processed by the gamma algorithm, the GUM algorithm and the CLAHE algorithm. The method solves the problem of low definition of the underwater degraded image, improves color distortion, improves image contrast and brightness, has obvious enhancement effects on different scenes, and has good generalization adaptability.

The invention discloses a multichannel synthetic aperture radar system channel equalization method based on sample selection. The method comprises the step 1: iteration initialization; the step 2: distance frequency domain frequency domain calibration; the step 3: doppler domain calibration; and the step 4: iteration termination condition determination, wherein if the iteration termination condition is satisfied, the process comes to an end, and if not, returning to the step 2. The multichannel synthetic aperture radar system channel equalization method based on sample selection effectively improves the performance for adaptive two dimension calibration. By adding a sample selection strategy before training an adaptive weight, the multichannel synthetic aperture radar system channel equalization method based on sample selection can effectively avoid the problem that in a traditional method, the low clutter noise ratio sample point in a sidelobe zone and a noise zone causes reduction of performance. The multichannel synthetic aperture radar system channel equalization method based on sample selection is suitable for compensation of the range and the phase error among channels for various different multichannel synthetic aperture radar systems, such as airborne, spaceborne and missile-borne multichannel synthetic aperture radars.

A wireless communication system includes first and second transceivers operable to transmit and receive signals over a communication channel using a plurality of modulation modes. A first signal is received which has been transmitted using a first modulation mode over the communication channel from the first transceiver to the second transceiver, and a first channel equalisation characteristic for an equaliser of a first type for receiving the first signal at the second transceiver is determined from measurements of the communication channel. From the first channel equalisation characteristic, a second channel equalisation characteristic is determined for an equaliser of a second type for a second modulation mode. A measure of a difference between the second and the first channel equalisation characteristics is determined, and the second modulation mode is selected for transmission over the communication channel from the first transceiver at least in part in dependence on the measure.

The invention belongs to the technical field of array signal processing, and particularly relates to a steady broadband frequency domain channel correction method based on singular value decomposition, which comprises the following steps: transmitting correction signals to receive channel echo data and calculating the frequency spectrum of each channel; selecting a reference channel; obtaining thefrequency response of each channel equalization filter; solving a filter coefficient matrix vector by a filter frequency response function of the equalization filter; and performing singular value decomposition on the Fourier transform matrix to solve the optimal solution of the filter coefficient of the equalization filter. The method has the beneficial effects of reducing the calculation amount, accelerating the calculation speed and being high in robustness.

The invention discloses a channel equalization method based on response estimation frequency domain fitting. The method comprises the following steps of: receiving echo data of a multi-channel linearfrequency modulation continuous triangular wave; obtaining I sample data of each frequency point l of the echo signal; calculating a covariance matrix of each frequency point l of the echo signal in asmoothing mode; calculating a rough estimation value of an amplitude ratio and a phase difference of the channel relative to the reference channel response on each frequency point l through covariance matrix eigenvalue decomposition; fitting by using a harmonic model of the least square criterion to obtain accurate estimation values of the amplitude ratio and the phase difference; calculating a channel frequency response and a fitted channel amplitude-frequency response according to the accurate estimation values of the amplitude ratio and the phase difference; calculating a fitted inter-channel phase-frequency response by using the frequency response of each channel; and obtaining an equalizer response by using the fitted channel amplitude-frequency response and the fitted inter-channelphase-frequency response. According to the channel equalization method, the signal-to-noise ratio of the channel response is improved, and the angle estimation error caused by eigenvalue diffusion canbe effectively reduced.

The invention provides a Ka-band DBF-SAR real-time processing system and method. The Ka-band DBF-SAR real-time processing system comprises: a data acquisition module, which uses different AD acquisition daughter boards to sample multi-channel intermediate frequency signals and performs framing and caching; the digital processing module is used for carrying out digital down-conversion on the cached multi-channel intermediate frequency signals to obtain multi-channel baseband signals, and sequentially carrying out filtering, extraction, improved DBF SCORE algorithm processing and multi-channel echo data synthesis; according to the improved DBF-SCORE algorithm, distance direction multi-channel DBF is carried out after channel equalization and pulse compression, and then the data downloading amount is reduced. The method has the advantages of real-time processing, multiple channels, high integration and the like, and is expected to play an important role in the millimeter wave SAR field.

An optical system including a ROADM including previously in-service channels; a SDN computing module in communication with the ROADM over a DCN, the SDN computing module providing an instruction to place in-service an additional channel at the ROADM; an optical controller included by the ROADM and configured to, in response to the instruction to place in-service the additional channel at the ROADM: obtain optical power targets for each in-service channel including the previously in-service channels and the additional in-service channel; equalize a transmit power for each in-service channel of the ROADM, including: identify the transmit power of each in-service channel; transition each in-service channel to a power mode; adjust the transmit power of each in-service channel based on, for each in-service channel, the optical power target for the in-service channel and the identified transmit power for the in-service channel; and transition each in-service channel to a steady state mode.

The invention discloses a system and a method for reproducing a sound field in an aircraft cabin by using a multi-channel balanced feedback method. A microphone is arranged at the position, over a seat, of the head of a passenger in an aircraft cabin, a loudspeaker is arranged under the seat under the microphone, and the microphone and the loudspeaker are in communication connection with a computer. Noise data in each state in the actual flight process is collected by the microphone arranged at a target point in the aircraft cabin to serve as a target sound field; the microphone and the loudspeaker are calibrated, an equalization matrix is measured and calculated; a multi-channel least square equalization mode is adopted for processing, and finally the loudspeaker is excited by an optimalsound source input signal to make a sound to realize reproduction of a sound field in the aircraft cabin. According to the invention, the multi-point space sound field in the cabin under various working conditions of the aircraft can be restored more accurately, a simulation experiment environment closer to the actual environment is provided, and the method can be used for improving the acoustic comfort in the cabin of the aircraft.

Methods for discontinuing interference-filter pre-coding of 8-VSB digital television (DTV) signals during ancillary-service transmissions are disclosed that do not disrupt reception of main-service DTV signals by receivers already in use. Receivers are disclosed for receiving ancillary-service transmissions without interference-filter pre-coding, which receivers include adaptive channel-equalization filters and subsequent decoders for CCC. The subsequent decoders for CCC respond to data slicing of adaptive channel-equalization filter responses that avoid the reduction of signal-to-noise ratio (SNR) caused by post-comb filtering. Certain of these M / H receivers employ selective post-comb-filtering to flatten the frequency spectrum of main-service components of received 8-VSB DTV signals, while leaving the frequency spectrum of M / H-service components of received 8-VSB DTV signals as received. This is done to generate signal from which filter coefficients for the channel-equalization filters are determined. Certain of these M / H receivers employ decision-feedback equalization (DFE) techniques, which techniques are unaffected by selective interference-filter pre-coding.

The invention belongs to the array signal technology, and relates to a method of equalizing unmatched channels in a certain bandwidth. The channel equalization method comprises the following steps: 1, a frequency domain equalization filter is converted into an N-point filter, and N is selected to be the least power no smaller than L, and the N-point frequency feature e<N><O> of the frequency domain equalization filter is solved; 2, each section filter coefficient for segmented equalization is solved; and 3, the eN is used for carrying out equalization processing on a baseband complex signal xA of the to-be-equalized channel, and a complex signal sequence xAE after equalization is obtained. The storage space needed by channel equalization can be reduced, the cancellation performance between channels is improved, the array processing performance is thus enhanced, and requirements of multichannel array signal processing by a modern communication system, a phased array radar system and the like can be met.

The invention provides a bidirectional DC-DC device for achieving a multi-channel equalization charge-discharge maintenance system of a lithium battery module. The device comprises a human-computer interaction layer, a module control layer and a charge-discharge control layer, wherein the whole device employs a charge-discharge unit modular design and a power modular design, the charge-discharge control layer employs a bidirectional DC-DC technology to achieve an equalization charge-discharge function of the lithium battery module and simultaneously achieve independent charge-discharge working system. Rapid equalization of the lithium battery module is achieved by an independent charge-discharge mode, moreover, the voltage / current control accuracy is higher, and the equalization effect of the lithium battery module is better.

The invention discloses a bistatic SAR channel equalization method based on echo data, aiming at solving the problem that the traditional method only equalizes the channel amplitude-phase inconsistency caused by a receiver, and the channel amplitude-phase inconsistency caused by an antenna feed line cannot be equalized due to mechanism reasons. The method performs range compression on echoes of areference channel and a channel to be equalized, compensates for the fixed phase difference of strong point target echoes caused by the inconsistency of the receiver channel position, and estimates the equalizer coefficients by the recursive least squares algorithm, so that the equalization filter is constructed. Finally, the echoes of the channel to be equalized are equalized by the equalizationfilter. The method directly processes the echoes passing through the channel to be equalized, does not need to obtain the equalization filter coefficient by using the training sample in advance, and avoids the influence of environment and time variation.

There is provided a device comprising a channel equalizer and a monitoring device, wherein the device is configured to establish a point-to-point network connection with a connected device via a network cable, by executing an initial training cycle so data received via the network cable is readable by the device. The channel equalizer is configured to continuously adapt to characteristics of the network cable by continuous training of the channel equalizer to help maintain the network connection, and the monitoring device is configured to monitor signals received from the network cable for out-of-range signals, to temporarily interrupt the continuous training of the channel equalizer when out-of-range signals are detected, and to resume the continuous training once the out-of-range signals are no longer detected without executing the initial training cycle again.

A semiconductor optical amplifier comprising an active gain region of the (In, Ga)(As, N) system is proposed, together with the use of (Ga, In)(As, N) as the base material for the fabrication of an SOA, and a semiconductor optical amplifier comprising (Ga, In)(As, N) as the base material. The N content of the (In, Ga)(As, N) can be varied along a dimension of the active region in the direction of propagation of light signals therein, to create a varying bandgap such as for mode expanders. The active region can be supplied by a source of electrical bias which is applied in segments along the dimension of the active region, the segments being capable of independent variation. This should allow channel equalisation of WDM signals to be performed dynamically. This scheme could also be used to equalise device parameters such as differential gain, saturation output power and linewidth enhancement factor across the amplification bandwidth.