This article presents a review of the investigation of the possibility of increasing the efficiency of existing line test solutions for troubleshooting testing for IPTV over xDSL, by the results of experimental research on real system under commercial exploitation. At the beginning of this article the main weaknesses of the existing troubleshooting testing are described. In the continuation of the article the physical layer parameters of xDSL transceiver are listed. In the reset this article provides a few specific examples of xDSL lines with their physical layer parameters of xDSL transceivers followed by analysis how they can be used for the purposes of more efficient measurement of parameters of copper pairs.

This paper presents a simple comparison between line conditions produced by using two types of local loops which operate in VDSL (Very-high-bit-rate speed Digital Subscriber line) environment. The object of observation is copper transmission line that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementing a FTTB (Fibre to the Building/Basement) solution. Two borderline loop types from opposite edges are used: purposefully manufactured DSL indoor cable and ordinary flat telephone indoor cable. The paper gives at first a short overview of previously introduced and verified short loop model in DSL, followed by brief description of its leading testing scenarios. After that, major testing scenarios are implemented on two observed loop types under same conditions. An explanation of obtained results with appropriate discussion is done at the end. Primary loop coefficients and transfer functions are used as observed quantities. All results of measurements and observations are collecting on real system in operation conditions.

This paper proposes an efficient algorithm for noise level estimation in still images. The images are assumed to be corrupted by additive white Gaussian noise. The proposed method relies on block-based image segmentation and Gaussian filtering to estimate the standard deviation of Gaussian noise. The proposed method employs adaptive image segmentation, where the size of segmentation blocks is derived from the initial estimates of noise standard deviation. Although image segmentation is a two-stage process that allows forming local noise level estimates from very small image patches, specific measures have been taken to improve computational efficiency of the proposed method. Image prefiltering is also adaptive in a sense that the coefficients of a Gaussian filter are evaluated as a function of the initial noise level estimate. The proposed method is designed to reduce the likelihood of underestimation of noise level due to intensity clipping. The results obtained on database of natural images show that the proposed scheme can accurately estimate the noise variance for a wide range of noise levels from very small to very high noise levels. In addition, it has been demonstrated that the proposed image segmentation scheme offers an accurate and consistent estimation of homogenous image patches.

This paper shows a review investigation the possibility of increasing the efficiency of existing line test solutions for troubleshooting IPTV over xDSL, by the results of experimental research on real system under commercial exploitation. At the beginning of this paper the main weaknesses of the existing troubleshooting testing are described. In the rest of the paper the parameters of the physical layer of xDSL transceiver are listed, followed by analysis how they can be used for the purposes of more efficient measurement of parameters of copper pairs.

Accurate and fast estimation of noise levels from medical images has numerous applications in medical image processing, including image enhancement, image segmentation and feature extraction. In this paper, a block-based noise level estimation algorithm in SVD domain is proposed. The proposed algorithm employs the non-overlapping block image segmentation to estimate homogenous image regions. Each homogenous block is used to obtain an independent noise level estimates in SVD domain. For any particular image, the overall noise level estimate is ascertained by averaging over the set of noise level estimates associated with the homogenous image blocks. In this paper, the optimal size of image segmentation blocks is evaluated systematically over a large dataset of x-ray images. The experimental results show that the proposed method offers numerous advantages over some alternative SVD domain method.

This paper introduces a very simple testing scenario for detecting of faults in copper local loop that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementation of FTTB (Fibre to the Building/Basement) solution. The scenario can be useful at first for quick and quite reliable loop troubleshooting, and in particular cases for loop qualification. The first part of the paper gives a short overview of copper loop model in DSL (Digital Subscriber Line) environment, its lead testing scenarios and FTTB solution. A main steps in fault analysis and testing scenario description follow. Below that, a discussion proposed scenario usability and reliability is provided. At the end an experimental verification of the scenario, which is based on data collecting on physical system in commercial exploitation is done.

This paper introduces a very simple model of copper local loop that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementing a FTTB (Fibre to the Building/Basement) solution. The model can be used for quick and quite reliable loop qualification and/or troubleshooting. The first part of the paper gives a short overview of copper loop model in DSL (Digital Subscriber Line) environment, its lead testing scenarios and FTTB solution. An explanation of main steps in developing of new model follows. Below that, a discussion model usability and reliability is provided. At the end an experimental verification of the model, which is based on data collecting on physical system in commercial exploitation is done.

This paper through the results of experimental research collected in real system under commercial exploitation investigates the significance of recommended ratio for one of physical layer parameter - SNR margin for the needs of loop qualification for IPTV over xDSL. At the beginning of this paper, a short definition and recommended value for SNR margin is given. In the rest of the paper the measured values of this parameter for 500 xDSL lines and made discussions the practical importance of this parameter for loop qualification are also given.

This paper continues already done research on the possibility for implementation and new test scenarios application for the problems detection in IPTV services delivered over DSL lines. Compared to the previous paper which research it continues, this paper provides a few specific examples of DSL lines in which, based on the values of physical layer parameters, we can assume with great certainty the real cause or a number of possible causes of problems in the IPTV service function. In this way the efficient elimination of identified problems is enabled.

This paper introduces a quite simple and comprehensible model of copper local loop in current DSL applications. The model is useful for engineers and other technical staff, who operate on local loop qualification and troubleshooting in order to evaluate its ability to provide reliable triple play service over DSL quickly. An overview of existing local loop model is presented briefly at the beginning of this paper. Based on pointed shortcomings of those models, a new one, which removes shortcomings, is proposed. A usability of proposed model in present-day conditions, especially in respect to broadband market situation, is analysed briefly.

This paper analyses the test scenarios of monitoring platforms of DSLAM devices and hand-held test instruments in terms of testing the physical layer parameters for the detection of problems in the functioning of the IPTV service. The paper carries out a comparison of both test abilities and analyses the advantages and disadvantages of each in comparison to the other. The paper also suggests optimal use of both test scenarios at very frequent testing on DSL lines.

This paper examines the actual usefulness and importance of longitudinal balance as one of many electrical parameters of symmetrical copper pairs. Through the results of several experiments on copper pairs with different types of significant faults, but also by measuring longitudinal balance on the real system in practice, this paper attempts to show the actual usefulness and importance of this parameter. In this manner, this paper intends to make the process of measuring the electrical parameters of symmetrical copper pairs more reliable and usable for reliable detection of various types of faults.

This paper analysis the actual usefulness and importance of wideband noise as one of electrical parameters of symmetrical copper pairs. By the results of measuring wideband noise on the real system in practice on copper pairs with different conditions on them, this paper attempts to show the actual usefulness and importance of this parameter. In this manner, this paper intends to make the process of measuring the electrical parameters of symmetrical copper pairs more reliable.

This paper shows an example of estimation and calculation of transfer function of twisted pair channel in DSL environment, from provider point of view, instead of commonly used manufacturers of transceivers ones. A brief overview of twisted pair as communication channel is given. End-to-end transfer function with twisted pair primary parameters as variables is introduced. The results of measurement on cable in commercial exploitation and its comparison with introduced theoretical approach are shown. The 20-pair, 1000-meter-long cable, completely buried, which had been 100% occupied by ADSL2+ signals and operating in rural conditions, is used.

This paper discovers what parameters of data link layer can be tracked to find relation between QoE (Quality of Experience) and QoS (Quality of Service). It also introduces a new paradigm that relates to consideration of parameters of QoS at all layers of OSI (Open System Interconnection) reference model, and their influence on QoE of end users. In order to analyse relation between data link layer parameters and QoE, the paper presents modification of IQX hypothesis (exponential interdependency of quality of experience and quality of service) in consideration with the mentioned parameters and time. As an example IPTV (Internet Protocol Television) scenario is shown.