White noise

About: White noise is a research topic. Over the lifetime, 16496 publications have been published within this topic receiving 318633 citations.

Minimal structural response under random excitation using the vibration absorber

Abstract: The equations of motion are derived for the first mode response of a linear multistorey structure having a linear vibration absorber attached to the roof. Furthermore, the variance of the first mode response to a gaussian white noise lateral base acceleration (as a model of earthquake excitation) is determined. Smallest possible values of the variance of the response along with corresponding absorber parameters are established using an optimization program. It is demonstrated that the absorber is quite effective in reducing first mode response for 5- and 10-storey structures even with relatively small values of the absorber mass. Moreover, minimal responses for the randomly excited single-degree-of-freedom system have been determined, and a design example is presented. The absorber system has potential application not only in earthquake engineering but also in aerospace and terrestrial vehicle design.

Minimum mean square equalization in cyclostationary and stationary interference-analysis and subscriber line calculations

Abstract: Equalization in cyclostationary interference, which occurs when similar neighboring digital communication systems cause interference (crosstalk), is considered. An expression is derived on the minimum mean square performance of a continuous-time infinite-length decision feedback equalizer in the presence of multiple cyclostationary interferers and additive white noise. This expression is calculated for a subscriber line system to show the performance improvements over the situation where the interference is stationary with the same power spectrum. Linear equalizer performance curves were also added to the comparisons. These results show two techniques which can provide opportunities for improved equalizer performance by enhancing the cyclostationarity of the interference. The first is by decreasing the misalignment of the phases of the transceiver clocks in the central office transmitters. The second is by using transmitter pulse bandwidths which are wide relative to the symbol rate. >

Extension of the signal subspace speech enhancement approach to colored noise

Abstract: The signal subspace approach for speech enhancement is extended to colored-noise processes. Explicit forms for the linear time-domain- and spectral-domain-constrained estimators are presented. These estimators minimize the average signal distortion power for given constraints on the residual noise power in the time and spectral domains, respectively. Equivalent implementations of the two estimators using the whitening approach are described.

Analysis of a Nonlinear First‐Order System with a White Noise Input

Abstract: A general technique for computing the power spectrum of nonlinear systems is presented, and the method is applied to the Brownian motion of a particle with idealized Coulomb damping. In this method the transition probability is obtained by solving the appropriate Fokker‐Planck equation. Then the autocorrelation function is calculated by an appropriate integration, and finally the power spectrum is found by means of the Wiener‐Khintchine relation. Comparison is made with the method of equivalent linearization, which is applicable to a wide class of nonlinear problems.

Quiescent pattern control in linearly constrained adaptive arrays

Abstract: When an adaptive array operates in the presence of white noise only, the resulting beam pattern is referred to as the quiescent response. Typically, these patterns have mainlobe and sidelobe shapes differing from those designed for use in deterministic, nonadaptive arrays. This paper describes a simple method which allows nearly arbitrary specification of the quiescent response in a linearly constrained power minimization adaptation array. The only restriction on the quiescent is that it must meet the constraints defined for the adaptive array. Since many well-known deterministic designs such as Chebychev are not likely to meet the linear constraint conditions used in adaptive arrays for mainlobe and other pattern control functions, a procedure is presented which modifies the deterministic design to force it to meet the linear constraints in a least-squares manner. Once this has been accomplished, the methods outlined in this paper can be used to cause the modified deterministic design to become the quiescent response of the adaptive array. As a result, the adaptive array can be configured to closely resemble a deterministic array when the noise is white. Under conditions of correlated interference, or jamming, however, the response changes so as to effectively steer nulls in the appropriate directions. The method is based on the use of a generalized side-lobe canceller and requires one additional linear constraint for both narrow-band and broad-band arrays.