234 results about "Impulse noise" patented technology

The invention discloses an image noise detection and denoising method based on a Hessian matrix, and the method comprises the steps: detecting a noise point through different characteristics of the feature value of the Hessian matrix of the noise point, an edge point and a smooth region point for impulse noise, employing the median filtering idea in a 3*3 window which takes the detected point as the center, employing the central value of the window to replace the noise point, and carrying out no processing for other points; proposing the concept of a noise point detection rate for the algorithm evaluation. Because the smooth region point or the edge point can be taken as the noise point during the detection of the noise point, a third discrimination condition is set for further improving the detection accuracy and denoising effect. For an image with the large noise density, the method also can obtain a better effect through multi-iteration. The method is better in denoising effect, and keeps more image edge and detail information. Compared with the median filtering, the method is better in effect under the condition of large noise density.

Several embodiments of a space diversity trellis interleaver system are provided for communicating data over a plurality of separate communication paths in order to inhibit distortion caused by impulse noise or other correlated noise and enhance the data transmission rate of data communications. The transmitter is designed to receive a plurality of data streams from data terminal equipment (DTE), which can be one or more devices. One or more convolutional encoders, preferably trellis encoders, encode each of the data streams. In an alternative embodiment, more than one trellis encoder is used to trellis encode each data stream. Data segments from the convolutionally encoded data streams are interleaved with a switch. The plurality of interleaved convolutionally-encoded data streams are modulated and transmitted onto a respective plurality of separate communication paths. At the receiver, the plurality of data streams is received from the separate communication paths and demodulated. The data segments are de-interleaved with a switch, and then the de-interleaved data streams are convolutionally decoded with convolutional decoders, preferably trellis decoders. The de-interleaved convolutionally decoded data streams are communicated to one or more DTEs.

The invention relates to a method for processing a video image, and discloses a method for de-noising an image. The method comprises the following steps of: A, calculating the joint probability distribution P(I,J) of the image; B, determining the threshold range [LI,UI] of gray scale according to the P(I,J); C, ensuring that Wi,j is a N*N window, the coordinate of a central point of the window is (i,j), x is used for representing the central pixel point of the window Wi,j, and the window Wi,j moves to the top left corner of the image; and D, sequencing N*N pixel points in the Wi,j according to gray scale values, finding a gray scale value J corresponding to a median (N*N+1) / 2 of the sequenced gray scale values, not processing the pixel point if J is in the threshold range [LI,UI] in the step B, and replacing the central point x of the window Wi,j with the gray scale value J if J is not in the threshold range [LI,UI]. The method has the advantage of solving the problems that image detail information is lost and the image blurs when pulse noise is removed by the conventional filtering method.

The invention discloses an electromagnetic pulse noise restraining method and device for detecting magnetoacoustic signals. The method comprises the following steps: the amplitudes and the pulse widths of synchronization pulses needed by a variable gain amplifier are calculated; synchronous pulse signals are set; the variable gain amplifier restrains electromagnetic pulse noise, and amplifies useful signals. The device comprises a power supply, a synchronous pulse generation device and the variable gain amplifier, wherein the power supply input end of the variable gain amplifier is connected with the power supply through a second isolating circuit; the reference voltage input end of the variable gain amplifier is connected with the power supply sequentially through a first voltage stabilizing circuit and a first isolating circuit; the gain control signal input end of the variable gain amplifier is connected with the synchronous pulse generation device for outputting control signals to the variable gain amplifier; the magnetoacoustic signal input end of the variable gain amplifier is connected with an ultrasonic transducer for outputting magnetoacoustic signals to the variable gain amplifier. The method and the device can effectively restrain the pulse electromagnetic noise doped in the weak signal detecting process, and can simultaneously realize the function of amplifying the detected signals.

Method and system for tolerating impulsive burst noise in pilot based OFDM systems, especially using DVB-T standard. The method contains following steps: 1) recognition of the impulse position and possibly length in the time domain symbol, 2) blanking of those samples of the symbol where significant amount of impulse noise is present, 3) calculating the first estimate of the received signal from the blanked symbol, 4) using a prior information (guard band carriers, pilot carriers) an estimate of the blanked symbol is calculated using inverse FFT on the differences of the observed carrier values from the known values in the frequency domain, 5) correction values for the frequency domain carriers are derived taking the FFT of the restored time domain samples, 6) finally the corrected estimate of the received symbol is derived by summing the correction values of step 5 to the first estimate of carriers derived in step 3. The method allows correction of relatively long bursts of impulse noise with minor degradation. The method provides considerably reliable data reception in broadcast systems.

The invention relates to an iterative channel estimation and impulse noise suppression method in an OFDM (Orthogonal Frequency Division Multiplexing) system, and belongs to the field of power line communication. The method is mainly divided into three parts: 1, detecting and inhibiting strong pulse interference under an expected false alarm probability through a self-adaptive threshold value obtained mathematically; secondly, carrying out channel estimation at a receiving end according to a known pilot signal inserted by a sending end; and 3, reconstructing residual pulse interference by using the signal after zero-forcing equalization and the deep neural network. And finally, the purposes of detecting and suppressing impulse noise, and iteratively realizing accurate channel estimation and good bit error rate are achieved. According to the method, the residual pulse interference which is not suppressed in channel estimation based on adaptive threshold zero setting is thoroughly eliminated, the performance is kept stable under the occurrence probability of various pulse interferences and various pulse interference intensities, and in most pulse interference environments, the performance equivalent to that of channel estimation without pulse interference can be achieved only through iteration for three times or within three times.

For voltage values (observed noise sequence) in an electronic power line (communication medium) which are obtained at a predetermined interval, initial values of noise characteristics based on a statistic of the observed noise sequence itself are decided by a moment method (S301 to S307), the noise characteristics (state transition probabilities and state noise power) for maximization of the likelihood of the observed noise sequence are obtained from the initial values by MAP (Maximum A Posteriori) estimation using a Baum-Welch algorithm (S309 to S312), a state sequence is estimated from the obtained noise characteristics, and an impulsive noise at each time point is detected.

With the current initialization procedures defined in the VDSL and ADSL standards, even though the xDSL system could operate in Showtime in an impulse noise environment where symbols are being corrupted, the transceivers would not be able to reach Showtime because initialization would fail due to initialization message failure. Through the use of an improved initialization procedure for communication systems, operation in environments with higher levels of impulse noise is possible.

An impulse detector which can detect both low and high levels of impulse noise in a CDMA system is comprised of circuitry to calculate the background noise level in unused codes. Another circuit calculates the average noise power in the unused codes of each spreading interval to output the noise power per spreading interval. This average is continuously averaged over spreading intervals by another circuit which outputs the average background noise power. A comparator compares the noise power in the current spreading interval with the background noise power plus a programmable threshold and generates an erasure indication if the background noise power plus a discrimination threshold is exceeded.