Recent Patents in Signal Processing (July 2015) – Adaptive Filtering

For our July 2015 issue, we cover recent patents dealing with various applications of adaptive filtering. The section below covers patents granted recently for reducing blocking effect and ringing noise, radio frequency spektrum analysis, filter bank implementation, signal amplifying, low complexity filtering, magnetic fluid analysis, signal canceling and filter representation.

In patent no. 9,060,181 a signal adaptive filtering method is proposed for reducing blocking effect and ringing noise, a signal adaptive filter, and a computer readable medium. The signal adaptive filtering method capable of reducing blocking effect and ringing noise of image data when a frame is composed of blocks of a predetermined size includes the steps of: (a) generating blocking information for reducing the blocking effect and ringing information for reducing the ringing noise, from coefficients of predetermined pixels of the upper and left boundary regions of the data block when a frame obtained by deconstructing a bitstream image data for inverse quantization is an intraframe; and (b) adaptively filtering the image data passed through inverse quantization and inverse discrete cosine transform according to the generated blocking information and ringing information. Therefore, the blocking effect and ringing noise can be eliminated from the image restored from the block-based image, thereby enhancing the image restored from compression.

Patent no. 9,048,919 introduces a system that incorporates teachings of the subject disclosure may include, for example, a method for identifying a spectral region in a radio frequency spectrum, determining a signal strength of the spectral region, determining a correlation factor by correlating the signal strength of the spectral region, identifying from the correlation factor interference in the spectral region, repeating a determination of the correlation factor and an identification of the interference until a desired confidence level has been achieved, and generating coefficient data to substantially suppress the interference in the channel responsive to achieving the desired confidence level.

According to patent no. 9,042,432 an adaptive filter bank can be implemented on a PLC device to dynamically adapt to variations in notching requirements and the performance of the PLC medium. The PLC device can apply filter coefficients to one or more filter elements of the adaptive filter bank to generate one or more notched subcarriers in the PLC band. A performance measurement of one or more subcarriers in the PLC band can be determined and evaluated against corresponding performance measurement thresholds. For a given notched subcarrier, if the performance measurement of the corresponding subcarriers is not in accordance with the performance measurement threshold, updated filter coefficients for the filter element configured to generate the notched subcarrier can be determined based, at least in part, on the performance measurement of the one or more subcarriers. The filter coefficients of the filter element can then be updated using the updated filter coefficients.

As described in patent no. 9,025,706, VGAs amplify a baseband reception signal using a prescribed gain. HPFs stop part, in a band lower than a first cutoff frequency, of the amplified reception signal. An ADC AD-converts an output signal of the HPFs and thereby outputs a digital reception signal. An AGC controller outputs a gain code corresponding to a prescribed gain of the VGAs. A VGA gain corrector adjusts the gain of the VGAs by a prescribed amount.

In patent no. 8,977,666 an adaptive filter is disclosed, having a plurality of computation groups, a plurality of computation circuits, a summation circuit, a slicer circuit, an updating circuit, and a control circuit. Each computation group corresponds to an equalization parameter and has a plurality of memory cells. When the corresponding equalization parameter of a computation group is greater than a predetermined value, the control circuit configures the computation group and the computation circuit to collaboratively generate an output of the computation group. The summation circuit sums up the outputs of the computation groups to produce a filter output. The slicer circuit generates a slicer output according to the filter output. The updating circuit updates the equalization parameters according to the filter output and the slicer output.

In patent no. 8,971,498 a contour collimator and an adaptive filter are proposed for adjusting a contour of a ray path of x-ray radiation is provided. The apparatus includes a magnetic fluid that is impermeable to x-ray radiation and a number of switchable magnet elements, by which an aperture forming the contour may be formed in the magnetic fluid.

According to patent no. 8,953,776, by using the adaptive filter, the reference input signal is processed so as to identify a pseudo-signal of a particular signal to be deleted. The pseudo-signal is subtracted from the mixture containing a target signal inputted from a microphone, the particular signal to be deleted, and a noise so as to obtain an error signal. A stationary noise is estimated to obtain a stationary noise estimated value. A non-stationary noise is estimated to obtain a non-stationary noise estimated value. The stationary noise estimated value is mixed with the non-stationary estimated value to obtain a mixed noise estimated value. An update amount is calculated according to a correlation value between the error signal and the reference input signal, and the mixed noise estimated value. According to the update amount, a coefficient of the adaptive filter is updated.

The invention no. 8,942,505 teaches a filter process used in intra or inter prediction of pixel blocks. A first, optionally interpolation, filter is applied in the first filter process to get filtered, optionally interpolated, pixel values. A differential filter and an adaptive gain are utilized in the second process for improving the prediction performance. The adaptivity of the gain can be made even on block basis, allowing a fine tuning of the pixel prediction and/or a fine tuning of pixel rotation and zooming. Alternatively, a combined one-step filter process using the interpolation filter, the differential filter and the adaptive gain is applied to the pixel values.

If you have an interesting patent to share when we next feature patents related to adaptive filtering techniques, or if you are especially interested in a signal processing research field that you would want to be highlighted in this section, please send email to Csaba Benedek (benedek.csaba AT sztaki DOT mta DOT hu).

References

Number: 9,060,181
Title:  Signal adaptive filtering method, signal adaptive filter and computer readable medium for storing program therefor  
Inventors: Y-I. Lee and H-W. Park
Issued:  June 16, 2015
Assignee: SAMSUNG ELECTRONICS CO., LTD. (Suwon-si, KR).

Number: 9,048,919
Title: Method and apparatus for an adaptive filter architecture
Inventors: A. Abdelmonem and S-S. Cordone
Issued:  June 2, 2015
Assignee: ISCO INTERNATIONAL LLC (Schaumburg, IL)

Number: 9,042,432
Title: Adaptive filter bank for dynamic notching in powerline communication
Inventors: M.W. Werner, S. Brueck and L.W. Yonge, III
Issued:  May 26, 2015
Assignee:  QUALCOMM Incorporated (San Diego, CA)

Number: 9,025,706
Title: Receiver with adaptive filter and gain control
Inventors: R. Kitamura
Issued: May 5, 2015
Assignee: Panasonic Corporation (Osaka, JP)

Number: 8,977,666
Title: Adaptive filter with reduced computational complexity
Inventors: C-Y. Huang and Y-L. Li
Issued: March 10, 2015
Assignee: Realtek Semiconductor Corp. (Hsinchu, TW)

Number: 8,971,498
Title: Contour collimator and adaptive filter having a magnetic fluid absorbing x-ray radiation and associated method
Inventors: S. Haider
Issued: March 3, 2015
Assignee: Siemens Aktiengesellschaft (Munchen, DE)

Number: 8,953,776
Title: Particular signal cancel method, particular signal cancel device, adaptive filter coefficient update method, adaptive filter coefficient update device, and computer program
Inventors: A. Sugiyama
Issued:  February 10, 2015
Assignee: NEC Corporation (Tokyo, JP)

Number: 8,942,505
Title: Adaptive filter representation
Inventors: K. Andersson
Issued:  January 27, 2015
Assignee: Telefonaktiebolaget L M Ericsson (Publ) (Stockholm, SE)