Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.

Acoustic echo suppression in the STFT domain

Abstract: We describe and evaluate an acoustic echo suppression method that operates in the short-time Fourier transform (STFT) domain The system estimates the short-time spectrum of the acoustic interference component that causes the echo at the far end and subtracts it from the short-time spectrum of the microphone input using a nonlinear spectral subtraction rule, allowing for a trade-off between speech distortion and residual rejection The interference estimator uses a set of decoupled adaptive FIR filters that operate on the STFT sub-band trajectories and that can be extended to include multiple acoustic channels The method is shown be efficient, and a viable and robust alternative to acoustic echo cancellation methods when the computation requirements are constringent

Frequency diversity telegraph system

Abstract: This invention relates to a frequency diversity telegraph system which is capable of providing continuous and positive operation at high speeds under serious fading and interference conditions, and more particularly to such a system which employs frequency modulation and frequency diversity

An FFT based technique for suppressing narrow-band interference in PN spread spectrum communications systems

Abstract: Analyses and performance predictions of an FFT-based narrowband interference suppression filter for use in PN (pseudonoise) spread-spectrum communications systems are presented. The received baseband signal is processed in fixed-length blocks, transformed to the frequency domain with an FFT, filtered there by using an appropriate weighting, and then transformed back to the time domain. A general expression for the symbol matched filter signal-to-noise ratio (SNR) is given in terms of signal parameters and filter weighting coefficients. An optimal (maximum SNR) filter scheme and several suboptimal thresholding algorithms are discussed. Performance predictions, based on a realistic high-frequency interference model, are presented for these algorithms and FFT-based architecture. >

Performance of antenna array systems with optimum combining in a Rayleigh fading environment

Abstract: The effect of cochannel interference on the performance of digital mobile radio systems in a Rayleigh fading environment is studied. The average bit error rate (BER) of an antenna array system with an optimum combining scheme that maximizes the output signal-to-interference-plus-noise ratio (SINR) is analyzed. BER expressions which are easy to evaluate numerically are derived for coherent binary phase shift keying (BPSK) schemes in an environment with cochannel interference and noise.

Multireflection optical multi/demultiplexer using interference filters

Abstract: A multireflection multi/demultiplexer using interference filters is proposed. Light waves of different wavelengths are combined or separated while they propagate between two filter arrays. The insertion loss of the 6-channel demultiplexer was around 1dB.