Mohamed M. E. El-Halawany

Blind separation of audio signals using trigonometric transforms and wavelet denoising

This paper deals with the problem of blind separation of audio signals from noisy mixtures. It proposes the application of a blind separation algorithm on the discrete cosine transform (DCT) or the discrete sine transform (DST) of the mixed signals, instead of performing the separation on the mixtures in the time domain. Wavelet denoising of the noisy mixtures is recommended in this paper as a preprocessing step for noise reduction. Both the DCT and the DST have an energy compaction property, which concentrates most of the signal energy in a few coefficients in the transform domain, leaving most of the transform domain coefficients close to zero. As a result, the separation is performed on a few coefficients in the transform domain. Another advantage of signal separation in transform domains is that the effect of noise on the signals in the transform domains is smaller than that in the time domain due to the averaging effect of the transform equations, especially when the separation algorithm is preceded by a wavelet denoising step. The simulation results confirm the superiority of transform domain separation to time domain separation and the importance of the wavelet denoising step.

Transmission Characteristics Evaluation Under Bad Weather Conditions in Optical Wireless Links with Different Optical Transmission Windows

Optical wireless links offer gigabit per second data rates and low system complexity. For ground space and or terrestrial communication systems, these links suffer from atmospheric loss mainly due to fog, scintillation and precipitation. Optical Wireless link provides high bandwidth solution to the last mile access bottleneck. However, an appreciable availability of the link is always a concern. Wireless Optics links are highly weather dependent and fog is the major attenuating factor reducing the link availability. Optical wireless links offer gigabit per second data rates and low system complexity. For ground space and or terrestrial communication scenarios, these links suffer from atmospheric loss mainly due to fog, scintillation and precipitation signals and then to upgrade the transmission bit rate distance product for ultra long transmission links. This paper has presented the bad weather effects such as rain, fog, snow, and scattering losses on the transmission performance of wireless optical communication systems. It is taken into account the study of bit error rate, maximum signal to noise ratio, maximum transmission optical path lengths and maximum transmission bit rates under these bad operating conditions.

Fusion of Zernike moments and Fourier-Mellin transform for invariant image resolution

We consider the use of Zernike moments (ZMs) for rotation- and scale-invariant classification of images. It is well known that ZMs are rotation-invariant only. We make use of the major benefit of the Fourier-Mellin (FM) transformation, which changes the rotation and the scale into translation. We introduce a new algorithm, which fuses the ZMs with the FM transform and is invariant under both rotation and scaling. Two sets of images were used to test the proposed algorithm. Experimental results reveal that the proposed algorithm has much better recognition rate than using ZMs within a variation of rotation between 0 and 360 deg, and scaling down and up between 25% and 400% of the original size.

Improved joint algorithms for reliable wireless transmission of 3D color-plus-depth multi-view video

Error control techniques like Error Resilience (ER) and Error Concealment (EC) are preferred techniques to ameliorate the lost Macro-Blocks (MBs) in the 3D Video (3DV) communication systems. In this paper, we present different enhanced ER-EC algorithms for intra-frame images for 3DV and Depth (3DV + D) communication through wireless networks. At the encoder, the slice structured coding, explicit flexible macro-block ordering, and context adaptive variable length coding are utilized. At the decoder, a hybrid approach comprising spatial circular scan order interpolation algorithm and temporal partitioning motion compensation algorithm is suggested to reconstruct the Disparity Vectors (DVs) and Motion Vectors (MVs) of the erroneous color images. For the corrupted depth images, a depth-assisted EC algorithm is proposed. Then, the optimum concealment MVs and DVs are chosen by employing the weighted overlapping block motion and disparity compensation algorithm. Furthermore, the Bayesian Kalman Filter (BKF) is utilized as an amelioration tool due to its efficiency to smooth the remnant inherent corruptions in the formerly optimally chosen color and depth DVs and MVs to obtain a good video quality. Simulation results on several 3DV streams show that the suggested algorithms have extremely adequate subjective and objective video quality performance compared to the traditional methods, particularly at high Packet Loss Rates (PLRs).

Proton radiation damage effects on the response of high speed communication avalanche photodiodes (notice of removal)

Abstract. This paper discusses the radiation dependent characteristics of avalanche photodiodes (APDs). The reliability, of semiconductor detectors, is very dependent on the degradation modes. In this study, we present the main irradiation effects such as the multiplication gain, minority carrier life time, illumination, and radiation damage coefficient. Protons radiation effects, on the model of two different silicon avalanche photodiode structures, has been investigated. The results demonstrate that the model can accurately calculate the internal parameters of the APDs and produce data that can be directly compared with measurements. The fluence effects of 51 MeV proton irradiation, on the photosensitivity and signal to noise ratio, are also investigated. The objective was to analyze the effect depletion region volume and carrier concentration, of the i-region of APDs, on radiation hardness. Moreover, we have investigated, deeply, some of the degradation performance and capabilities of typical APDs, currently used in many communication and sensing systems, over wide range of the affecting parameters. APDs are used in systems that require coherent, and often single mode, light such as high data rate communications and sensing applications. APDs are an attractive receiver choice for low signal applications because their internal gain mechanism can improve signal to noise ratio. Additionally, we have taken into account the harmful effects of proton radiation on the device performance such as signal to noise ratio, bit error rate, gain, sensitivity, device responsitivity and operating efficiency.

Separation of speech signals using trigonometric transforms

This paper deals with the problem of blind separation of signals from noisy mixtures. It proposes the application of a blind separation algorithm on the discrete cosine transform (DCT) or the discrete sine transform (DST) of the mixed signals, instead of performing the separation on the mixtures in the time domain. Both the DCT and the DST have an energy compaction property, which concentrates most of the signal energy in a few coefficients in the transform domain, leaving most of the transform domain coefficients close to zero. As a result, the separation is performed on a few coefficients in the transform domain. Another advantage of signal separation in transform domains is that the effect of noise on the signals in the transform domains is smaller than that in the time domain. As an application, the separation of audio signals in a noisy environment is studied in time and transform domains. The simulation results confirm the superiority of transform domain separation to time domain separation.

Simultaneous blind signal separation and denoising

This paper deals with the problem of blind separation of denoising. It proposes the application of the discrete wavelet transform as a preprocessing step of denoising prior to the blind separation algorithm. The separation of sinusoidal signals as well as speech signals in a noisy environment is studied with and without the use of the wavelet denoising step. The simulation results confirm the usefulness of this step. In all our simulation experiments, soft thresholding is used.