42 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 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 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.

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.

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.

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.

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 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.

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.

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.