In continuous wave (CW) radar systems, the efficiency of semi-active chaser receiver in the tracking of target is of paramount importance. In a situation where the target and chaser have variable speed (accelerated motion) relative to one another, in the semi-active chaser receiver, the received signal has time varying Doppler frequency shifts. In this paper, semi-active receiver with hierarchical features first acquires an estimation of the parameters of the received signal using the short time-frequency transform (STFT) at the time of the acceleration of the target or chaser. Then, mono-pulse angular tracking accuracy is tested using a matched filter based on the estimated parameters of the received signal. Eventually, providing the required simulation, the proposed method is compared with “ maximum signal spectrum” and “ average signal spectrum” methods. The results imply that the matched filter-based algorithm has a better performance than other algorithms.

This paper presents a new approach for estimating the signal-to-noise ratio (SNR) of mixture signal, which is based on the computational auditory scene analysis (CASA). The ideal binary mask (IBM) which is generally the computational goal of CASA based systems is used to estimate the SNR of noisy speech signal. The proposed method is evaluated using IBM and some quasi-IBM masks. The method is simple and computationally efficient. Systematic evaluations show that the proposed method results in reasonable estimation of the input SNR level in a wide range of SNR values, and probable errors in estimating IBM do not affect so much the performance of the proposed system. Furthermore, simulation results show that the proposed system outperforms previous SNR estimation methods.

Many important speech enhancement methods operate in frequency domain. In these methods, a frequency gain filter is multiplied by the noisy spectrum. In this paper, frequency methods are investigated and the gain filters are shown as functions of the Signal to Noise Ratio (SNR). Since gain filters are functions of SNR, SNR estimation methods are presented and consequently a new SNR estimation method is proposed. Moreover, we proposed a technique for controlling the level of residual noise and shaping it. In our proposed techniques, the frequency gain filters are tuned in order to have less noise reduction and as a result achieve less distortion. In addition to controlling the level of noise, in our proposed technique, the shape of residual noise is changed in order to have more pleasant residual noise. For evaluation of methods, listening tests are performed and the results are reported based of four aspects of speech signals: musical residual noise, level of background noise, echo and unnatural residual noise. Evaluation of methods shows that the proposed methods are successful from these aspects point of view.

This paper concerns two-hop communication over relay-assisted Block fading channel. It is assumed there is not a direct link between the transmitter and the affiliated destination and the communication occurs in two hops through the use of a relay, where the amplify and forward (AF) strategy is employed at this node. In this case, in a Rayleigh block fading channel, the optimal weight function at the relay in terms of maximizing the received signal to noise ratio (SNR) at the destination is derived, assuming the relay is aware of channel gains associated with both hops and that the relay is subject to an average power constraint. Finally, the resulting SNR is compared to the case of having a peak power constraint at the relay which is served as a benchmark throughout the simulations.

In this article, an attempt has been made to estimate the amount of sound transmission loss in a flat oval channel by applying the approach of statistical energy analysis. Correct estimation of sound transmission loss in an air conditioning channel is of great importance due to the harmful effects of noise pollution in the environment on human health. Simulation with the statistical energy analysis method is a powerful approach to estimate sound and vibration in problems in which we deal with complex and multi-part systems; is considered. In this method, first, a system is divided into several subsystems, and then by writing a matrix equation that includes the energy exchanges between subsystems and energy loss coefficients; It is investigated from the perspective of vibration and sound estimation.On average, the model presented in this research is able to estimate the sound transmission loss in different dimensions of the air conditioning channels according to the experimental results in the accuracy range of ± 2.5 dB. Considering that it seems that the results obtained from modeling with this method are in good agreement with the experimental data; The results of this research can be used as an efficient approach to estimate noise in oval shaped channels stretched in different lengths.