Topic
Noise measurement
About: Noise measurement is a research topic. Over the lifetime, 19776 publications have been published within this topic receiving 308180 citations.
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Patent•
12 Feb 1999
TL;DR: In this paper, the thresholds for noise and voice are periodically updated based on the minimum and maximum energy levels measured for block energies, where the revised thresholds are based upon a factor of the minimum energy levels of the current block and most recent past block and the average energy of the previous blocks.
Abstract: A method of discriminating noise and voice energy in a communication signal. A signal is measured in a plurality of block periods, which are sampled to obtain a measurement of the block energy value for the signal. The blocks are compared to a noise threshold and to a voice threshold to discriminate between noise and voice. The thresholds for noise and voice are periodically updated based on the minimum and maximum energy levels measured for block energies. In a preferred embodiment, the voice energy threshold and noise energy threshold values are updated according to a formula where the revised thresholds are based upon a factor of the minimum and maximum energy levels of the current block and the most recent past block and the average energy of the previous blocks. Updating of threshold levels allows for more accurate estimation of noise and voice during changes in either noise, voice or both to avoid missclassification of noise and/or voice.
75 citations
TL;DR: The results strongly suggest the method's effectiveness in removing the influence of background activity in source estimation for auditory-evoked fields elicited by syllable speech sounds.
Abstract: This paper proposes a method of localizing multiple current dipoles from spatio-temporal biomagnetic data. The method is based on the multiple signal classification (MUSIC) algorithm and is tolerant of the influence of background brain activity. In this method, the noise covariance matrix is estimated using a portion of the data that contains noise, but does not contain any signal information. Then, a modified noise subspace projector is formed using the generalized eigenvectors of the noise and measured-data covariance matrices. The MUSIC localizer is calculated using this noise subspace projector and the noise covariance matrix. The results from a computer simulation have verified the effectiveness of the method. The method was then applied to source estimation for auditory-evoked fields elicited by syllable speech sounds. The results strongly suggest the method's effectiveness in removing the influence of background activity.
75 citations
TL;DR: An efficient denoising scheme and its VLSI architecture for the removal of random-valued impulse noise is proposed and can obtain better performances in terms of both quantitative evaluation and visual quality than the previous lower complexity methods.
Abstract: Images are often corrupted by impulse noise in the procedures of image acquisition and transmission. In this paper, we propose an efficient denoising scheme and its VLSI architecture for the removal of random-valued impulse noise. To achieve the goal of low cost, a low-complexity VLSI architecture is proposed. We employ a decision-tree-based impulse noise detector to detect the noisy pixels, and an edge-preserving filter to reconstruct the intensity values of noisy pixels. Furthermore, an adaptive technology is used to enhance the effects of removal of impulse noise. Our extensive experimental results demonstrate that the proposed technique can obtain better performances in terms of both quantitative evaluation and visual quality than the previous lower complexity methods. Moreover, the performance can be comparable to the higher,- complexity methods. The VLSI architecture of our design yields a processing rate of about 200 MHz by using TSMC 0.18 μm technology. Compared with the state-of-the-art techniques, this work can reduce memory storage by more than 99 percent. The design requires only low computational complexity and two line memory buffers. Its hardware cost is low and suitable to be applied to many real-time applications.
75 citations
Patent•
22 Jun 2007
TL;DR: In this paper, a system for facilitating conversational communications in an environment with background noise, including a microphone for sensing the background noise and a signal processor configured to process the microphone output and produce an anti-noise electrical output, was presented.
Abstract: A system for facilitating conversational communications in an environment with background noise, the system including a microphone for sensing the background noise, a signal processor configured to process the microphone output and produce an anti-noise electrical output, and a directional speaker array configured to receive the anti-noise electrical output and directionally broadcast anti-noise audio output, the anti noise audio output destructively interfering with the environmental background noise.
75 citations
27 May 1992
TL;DR: In this paper, a cooling sapphire microwave resonator was used to characterize the phase noise of a single crystal quartz oscillator of the highest quality, without the use of a second similar oscillator as reference.
Abstract: First results are presented for an X-band frequency discriminator using a cooled sapphire microwave resonator. These results show a lower close-in (1-Hz-1-kHz offset) phase noise measurement floor than any oscillator presently available. This performance is made possible by a sapphire whispering-gallery mode resonator which shows the highest quality factor (with Q's up to 30 million) of any RF microwave, or acoustic resonator at temperatures to 77 K. Performance is increased by use of phase detection circuitry. The sapphire discriminator is used to characterize the phase noise of a single crystal quartz oscillator of the highest quality, without the use of a second similar oscillator as reference. >
74 citations