noise reduction by oversampling

... concentration Reduction rate 103 kg·y-1 mg·L-1 % Case 9.65 31.0 - Case 9.30 29.9 Case 8.60 27.6 11 CONCLUSIONS A distributed water quality tank model was developed to simulate nitrogen load reduction by ... elevation, land use and drainage data were added to each cell and were determined by means of a field investigation by using a land-use map and a 1:5,000 map (Fig 3) The Geographical Survey Institute ... the river; point B, the drainage in the paddy fields surrounded by forests; point C, the drainage of the paddy fields surrounded by the upland fields; and point D, the spring water near the livestock...

Ngày tải lên: 05/09/2013, 09:08

... filter can be used to remove the out–of–band noise 1.3.8 Dolby Noise Reduction Dolby noise reduction systems work by boosting the energy and the signal to noise ratio of the high–frequency spectrum ... tape have smaller signal–to noise ratio than the low–frequency parts Therefore noise at high frequencies is more audible and less masked by the signal energy Dolby noise reduction systems broadly ... each other in order to avoid processing distortion Dolby has developed a number of noise reduction systems designated Dolby A, Dolby B and Dolby C These differ mainly in the number of bands and...

Ngày tải lên: 21/01/2014, 07:20

... Transient noise pulses: consists of relatively long duration noise pulses 2.2 White Noise White noise is defined as an uncorrelated noise process with equal power at all frequencies (Figure 2.1) A noise ... other noise processes are non-white The term coloured noise refers to any broadband noise with a non-white spectrum For example most audiofrequency noise, such as the noise from moving cars, noise ... (a) A brown noise signal and (b) its magnitude spectrum Fs /2 Noise and Distortion 34 2.4 Impulsive Noise Impulsive noise consists of short-duration “on/off” noise pulses, caused by a variety...

Ngày tải lên: 21/01/2014, 07:20

... index The collection of noise on different lines form the ensemble (or the space) of the noise process denoted by N(m)={n(m,s)}, where n(m,s) denotes a realisation of the noise process N(m) on ... power spectrum of white noise Example 3.6 Power spectrum and autocorrelation of white noise (Figure3.6) A noise process with uncorrelated independent samples is called a white noise process The autocorrelation ... considered some applications of stochastic processes for modelling random noise such as white noise, clutters, shot noise and impulsive noise Bibliography ANDERSON O.D (1976) Time Series Analysis and Forecasting...

Ngày tải lên: 21/01/2014, 07:20

... posterior space is obtained by subtracting the noise mean vector from the noisy signal vector The clean signal is then somewhere within a subspace determined by the noise variance 100 Bayesian ... matrix Σxx, and that the noise n(m) is also Gaussian with mean vector µn and covariance matrix Σnn The signal and noise pdfs model the prior spaces of the signal and the noise respectively Given ... x, and n is an additive random noise process In Figure 4.1, the distributions of the random noise n, the random input e and the parameter vector θ are modelled by probability density functions,...

Ngày tải lên: 21/01/2014, 07:20

... and the noise HMMs maybe expressed as   MAP s signal = arg max  max f Y (Y , ssignal , s noise M ,η )  s signal  s noise (5.46)   MAP s noise = arg max  max f Y (Y , ssignal , s noise ... rapidly in the presence of noise, since noise causes a mismatch between the clean HMMs and the noisy signals The noise- induced mismatch can be reduced: either by filtering the noise from the signal ... Modelling Noise Characteristics The implicit assumption in using an HMM for noise is that noise statistics can be modelled by a Markovian chain of N different stationary processes A stationary noise...

Ngày tải lên: 21/01/2014, 07:20

... Filter for Additive Noise Reduction Consider a signal x(m) observed in a broadband additive noise n(m)., and model as y(m) = x(m) + n(m) (6.45) Assuming that the signal and the noise are uncorrelated, ... separability: (a) The signal and noise spectra not overlap, and the signal can be recovered by a low-pass filter; (b) the signal and noise spectra overlap, and the noise can be reduced but not completely ... of Signal and Noise A signal is completely recoverable from noise if the spectra of the signal and the noise not overlap An example of a noisy signal with separable signal and noise spectra is...

Ngày tải lên: 21/01/2014, 07:20

... constant signal observed in noise Consider the estimation of a constant signal observed in a random noise The state and observation equations for this problem are given by x(m)= x(m − 1) = x y(m) ... examination of the LMS equation shows that for applications in which the LSE is non-zero such as noise reduction, the incremental update term µe(m)y(m) would remain non-zero even when the optimal ... Filtering Automatica, 21, pp 293–302 GABOR D., WILBY W P and WOODCOCK R (1960) A Universal Non-linear Filter, Predictor and Simulator which Optimises Itself by a Learning Process IEE Proc 108, pp 422–38...

Ngày tải lên: 21/01/2014, 07:20

... recognition Speech is generated by inhaling air and then exhaling it through the glottis and the vocal tract The noise- like air, from the lung, is modulated and shaped by the vibrations of the glottal ... signal and the noise processes For example, the frequency spectrum of a linear prediction model of speech, observed in additive white noise, would be flatter than the spectrum of the noise- free speech, ... predictor coefficients vector due to the noise A simple method for removing the effects of noise is to subtract an estimate of the autocorrelation of the noise from that of the noisy signal The...

Ngày tải lên: 21/01/2014, 07:20

... filter can be used to remove the out–of–band noise 1.3.8 Dolby Noise Reduction Dolby noise reduction systems work by boosting the energy and the signal to noise ratio of the high–frequency spectrum ... 2.2 White Noise 2.3 Coloured Noise 2.4 Impulsive Noise 2.5 Transient Noise Pulses N 2.6 2.7 2.8 2.9 2.10 Thermal Noise Shot Noise Electromagnetic Noise Channel Distortions Modelling Noise oise ... each other in order to avoid processing distortion Dolby has developed a number of noise reduction systems designated Dolby A, Dolby B and Dolby C These differ mainly in the number of bands and...

Ngày tải lên: 25/01/2014, 13:20

... Chapter provides an introduction to noise and distortion Several different types of noise, including thermal noise, shot noise, acoustic noise, electromagnetic noise and channel distortions, are ... TRANSIENT NOISE PULSES 378 13.1 Transient Noise Waveforms 379 13.2 Transient Noise Pulse Models 381 13.2.1 Noise Pulse Templates 382 13.2.2 Autoregressive Model of Transient Noise ... of a Noise Pulse Process .384 13.3 Detection of Noise Pulses 385 13.3.1 Matched Filter for Noise Pulse Detection 386 13.3.2 Noise Detection Based on Inverse Filtering 388 13.3.3 Noise...

Ngày tải lên: 25/01/2014, 13:20

... model is described by Equation (9.47) The relationship between the ARMA parameters and the autocorrelation sequence can be obtained by multiplying both sides of Equation (9.47) by x(m–j) and taking ... with the largest eigenvalues; (b) the noise subspace represented by the smallest eigenvalues The decomposition of a noisy signal into a signal subspace and a noise subspace forms the basis of the ... additive white noise, the autocorrelation function is given by P ryy (k ) = ∑ Pi cos 2kπFi + σ n δ (k ) (9.87) i =1 where Pi = Ai / is the power of the sinusoid Ai sin(2πFi), and white noise affects...

Ngày tải lên: 26/01/2014, 07:20

... change a sampling rate by a factor of V=I/D (where I and D are integers), the signal is first interpolated by a factor of I, and then the interpolated signal is decimated by a factor of D Consider ... the Nyquist rate, the baseband spectrum X(f) is not overlapped by its images X(f±kFs), and the original signal can be recovered by a low-pass filter as shown in Figure 10.1 Hence the ideal interpolator ... sampling rate can be increased by a factor of I through interpolation of I–1 samples between every two samples of x(m) In the following it is shown that digital interpolation by a factor of I can be...

Ngày tải lên: 26/01/2014, 07:20

... signal, the noise is accessible on a separate channel, it may be possible to retrieve the signal by subtracting an estimate of the noise from the noisy signal For example, the adaptive noise canceller ... is unity We denote the power spectrum by E [| X ( f ) | ] , the time-averaged power spectrum by X ( f ) and the instantaneous power spectrum by X ( f ) By expanding the instantaneous power spectrum ... by sd ( | N ( f ) | ) α (SNR ( f ) ) = + (11.26) | N( f )| where the function sd(|N(f)| is the standard deviation of the noise at frequency f For white noise, sd(|N(f)|=σn, where σ n is the noise...

Ngày tải lên: 26/01/2014, 07:20

... impulsive noise 362 Impulsive Noise 12.2.2 Poisson–Gaussian Model of Impulsive Noise In a Poisson–Gaussian model the probability of occurrence of an impulsive noise event is modelled by a Poisson ... impulsive noise and the interpolator is bypassed A detector output of “1” signals the presence of impulsive noise, and the interpolator is activated to replace the samples obliterated by noise 12.4.1 ... impulsive noise to excitation signal ratio is given by impulsive noise power E[ni2 (m)] = excitation power E[e (m)] (12.30) The overall gain in impulsive noise to signal ratio is obtained, by dividing...

Ngày tải lên: 26/01/2014, 07:20

... time-align the noise pulse template with the noise pulse The template energy is adaptively matched to that of the noise pulse by an adaptive scaling coefficient w The scaled and time-aligned noise template ... book of transient noise pulses can be designed by collecting a large number of training examples of the noise, and then using a clustering technique to group, or partition, the noise database into ... the characterisation of a set of transient noise pulses The clustering of a noise process is based on a set of noise features that best characterise the noise Features derived from the magnitude...

Ngày tải lên: 26/01/2014, 07:20

... down-sampled by the same factor R The main advantages of a sub-band echo canceller are a reduction in filter length and a gain in the speed of convergence as explained below: (a) Reduction in ... 14.4 Adaptive Echo Cancellation Echo cancellation was developed in the early 1960s by AT&T Bell Labs and later by COMSAT TeleSystems The first echo cancellation systems were experimentally implemented ... surfaces and then picked up by the microphone In its worst case, acoustic feedback can result in howling if a significant proportion of the sound energy transmitted by the loudspeaker is received...

Ngày tải lên: 26/01/2014, 07:20

... this can lead to noise amplification if the signal-to -noise ratio is low 15.1.2 Equalization Error, Convolutional Noise The equalization error signal, also called the convolutional noise, is defined ... each sample of convolutional noise is affected by many samples of the input process From the central limit theorem, the convolutional noise e(m) can be modelled by a zero-mean Gaussian process ... X ( f )H ( f )+ N ( f ) (15.3) Noise n(m) x(m) Distortion y(m) H(f) f –1 Equaliser ^ x(m) H (f) f Figure 15.1 Illustration of a channel distortion model followed by an equalizer 418 Equalization...

Ngày tải lên: 26/01/2014, 07:20

... OmcB-dependent Fe(III)-nitrilotriacetic acid reduction by either V(V), U(VI), or Se(VI) Only V(V) appears to significantly inhibit Fe(III) reduction, as characterized by IC50s of 10.7 lm and 81.4 lm for ... Microbial reduction and precipitation of vanadium by Shewanella oneidensis Appl Environ Microbiol 69, 3636–3639 Klonowska A, Heulin T & Vermeglio A (2005) Selenite and tellurite reduction by Shewanella ... obtained using either omcA– [OmcBdependent Fe(III) reduction] , omcB– [OmcA-dependent Fe(III) reduction] or MR-1R [OmcA + OmcBdependent Fe(III) reduction] cells In the absence of Table Enzymatic...

Ngày tải lên: 07/03/2014, 09:20

... of these GPX isoenzymes are shown by inverted triangles The GPX conserved regions are shown by a horizontal line below the amino acid residues and represented by I, II and III GenBankTM accession ... spectrophotometrically at 340 nm by the decrease in the absorbance due to the conversion of NADPH in the presence of GSH reductase, which catalyzes the reduction of oxidized GSH formed by GPX [14] The reaction ... expression was induced by the addition of 0.4 mm isopropyl-thio-b-d-galactoside Cells were further A thaliana glutathione peroxidases grown for 24 h at 15 °C with shaking, collected by centrifugation...

Ngày tải lên: 16/03/2014, 12:20