61 results about "Impulse noise detection" patented technology

A receiver recovers data from Orthogonal Frequency Division Multiplexed (OFDM) symbols, the OFDM symbols including sub-carrier symbols carrying data symbols and sub-carrier signals carrying pilot symbols. The receiver includes a Fourier transform processor arranged in operation to receive a time domain digital version of the OFDM symbols and to form a frequency domain version of the OFDM symbols, from which the pilot symbol sub-carriers and the data symbol bearing sub-carriers can be recovered, and a detector arranged in operation to recover the data symbols from the data bearing sub-carriers of the OFDM symbols. The receiver includes a noise estimator arranged in operation to generate a long term estimate of noise power in the frequency domain version of the OFDM symbols at a plurality of frequencies, by accumulating an average noise power at the plurality of frequencies from a plurality of the OFDM symbols, and for generating an estimate of a current level of the noise power in the frequency domain version of a current one of the OFDM symbols at the plurality of frequencies. An impulsive noise detector detects the presence of an impulse of noise in the current OFDM symbol, by comparing the noise power in the current OFDM symbol with the long term noise power at the plurality of frequencies, and to generate an impulse noise flag to indicate that the current OFDM symbol is affected by an impulse of noise if the comparison indicates the presence of an impulse of noise. Impulsive noise in the time domain will generate an increase in noise level across the frequency bandwidth of the OFDM symbols. If all frequencies experience an increase then an impulse of noise can be detected. Thereafter the detector can conceal the effect of the impulse noise on the recovering of the data symbols from the data bearing sub-carriers, for example by adapting channel state information for use in de-mapping modulated symbols into data symbols.

A method of detecting both linear and non linear noise in video data. Linear noise is detected on a line-by-line basis, by blocks within each line. Non linear noise is detected during horizontal blanking periods. The method provides a noise floor value for linear noise and an impulse noise flag for non linear noise, both of which are delivered to a noise reduction filter.

The invention discloses a method and a device for eliminating impulse noise, and belongs to the field of communication. The method comprises the following steps of: acquiring a carrier wave periodically to acquire time-domain signals which are included within a period; selecting a time-domain signal of which the signal power is smaller than a preset power threshold value from the time-domain signals which are included within the period; calculating average power according to the signal power of the selected time-domain signal; and detecting and eliminating the impulse noise in the time-domain signals which are included within the period according to the average power. The device comprises an acquisition module, a first selection module, a first calculation module and a first elimination module. According to the method and the device, the average power is calculated according to the selected time-domain signal of which the signal power is smaller than the preset power threshold value; and the impulse noise in the time-domain signals is detected and eliminated according to the average power to improve the accuracy of detecting the impulse noise, so that the influence of the impulse noise on the time-domain signals can be eliminated better.

According to one embodiment, a noise reduction apparatus includes a frame delay module, first and second impulse noise detectors, first and second impulse noise reducers, a motion detector, and a noise reducer. The frame delay module delays a video signal by one frame to obtain a frame delay video signal. The first and second impulse noise detectors detect impulse noise in the video signal and the frame delay video signal. The first impulse noise reducer generates a current frame video signal by reducing the impulse noise in the video signal. The second impulse noise reducer generates a previous frame video signal by reducing the impulse noise in the frame delay video signal. The motion detector detects motion amount from the current and previous frame video signals. The noise reducer reduces noise other than the impulse noise in the current frame video signal based on the motion amount.

The embodiment of the invention discloses a method, device and system for detecting pulse noise, relating to the field of communication, and aiming to solve the problems that the pulse noise detection method is complex and has lower detection accuracy and sensitivity in the prior art. The technical scheme provided by the invention comprises the following steps: selecting continuous sampling points in accordance with the number of preset first sampling points from received time domain signals; acquiring an amplitude difference set of sampling points in accordance with preset detection intervals in the sampling points; and judging whether the time domain signals have pulse noise according to the amplitude difference set. The technical scheme provided by the embodiment of the invention can be applied to a pulse noise detection technique of various digital signal processing systems such as DSL (digital subscriber line), Cable and other wired access modes, wireless access, WIFI (wireless fidelity) or 3G (the 3rd generation telecommunication) and the like.

The invention discloses a coherent noise filtering method and a system. The filtering method comprises the following steps: obtaining measured power signal parameters; starting from the first measuredpower signal of the measured power signal sequence, an iterative algorithm being used to select L power signals to determine the power vector; determining a historical background noise according to the power vector; determining a filter parameter of a coherent noise filter according to the historical background noise; determining a weight of the coherent noise filter according to the historical background noise using an optimization criterion of minimizing signal variance; obtaining the power and the serial number of the measured power signal to be filtered out; according to the historical background noise, the filtering parameter, the weight, the power and the serial number of the measured power signal to be filtered, filtering the background noise of the measured power signal to be filtered, and determining a noise-free power signal. The filtering method and the system provided by the invention can improve the impulse noise detection accuracy and the coherent noise filtering accuracy.

The invention provides an impulse noise detection method in an OFDM communication system, comprising the following steps: setting a judgment threshold based on the average energy of the null subcarriers of at least one OFDM symbol in an OFDM communication system; estimating the average energy of the null subcarriers of subsequent OFDM symbols, comparing the average energy with the judgment threshold, and judging whether there is impulse noise; and updating the judgment threshold according to the comparison result, and giving an instruction on whether there is impulse noise detected. Impulse noise is detected based on the fact that data is not modulated on the null subcarriers in an OFDM communication system, energy mainly comes from leaked energy of Gaussian noise and adjacent subcarriers, and the energy of impulse noise is usually significantly higher than that of Gaussian noise.

The invention provides a pulse noise detection method based on a local extremum value and application of the pulse noise detection method to a video fault diagnosis system. By using the method, pulse noise in an image can be effectively and accurately detected and the false detection on the detailed information in the image can be avoided, thereby the intelligent video fault diagnosis and analysis can be realized.