## 3 Evaluation of Melt Test Parameters and Analysis of DSL Service Provision
### Evaluation of MELT Test Parameters in the Mobile Application  
In this section, the functionalities of the mobile application for evaluating MELT test parameters and for analyzing appropriate homogeneous symmetric lines for DSL service provision are introduced. The mobile application is installed on a tablet that runs with the Android operating system. The application is called \"Evaluation of the MELT test\". Figure 2: Example of the comparison involving the ranges of evaluated parameters and analyzed quantities. Since the test parameter data come from a test software tool that is reserved only for the telecommunication operator, the data obtained from the test measurements are inadaptable in a different area than the created mobile application from a security viewpoint. They are not transferred directly from the test software tool to the mobile application. Data from the test software tool are available as an export in a specific CSV file format. In this way, data are entered into the mobile application that is not available for the commercial market. The mobile application can recognize uncorrected data entry and warns the user to enter corrected data. Data in the mobile application are evaluated once, without any memory recording and without any transmitting, so they cannot be misused. After launching the mobile application, the user can see the main page of the application with nine quantities (see Section 3.2). The measured values of quantities are loaded by the virtual keypad to the corresponding quantity. In total, three categories of quantities (DC/AC foreign voltages and C capacity) are evaluated, where the first quantity from the group is also listed the unit that characterizes the quantity. After entering all the parameters, it is necessary to click on the Evaluate button in the upper right corner. After clicking on the button, the results of the evaluation of the measured test parameter values and analysis of individual quantities, as well as the overall evaluation of the MELT test, are displayed at the bottom of the screen. The evaluation of measured values consists of GOOD/WARNING/FAIL message statements, where the GOOD message is colored in green, WARNING in yellow and FAIL in red. The analysis of the quantity consists of the extraction of the report; for example, \"The quantity corresponds to the range\". If a measured value is evaluated by the WARNING/FAIL message, the possible cause of the failure is also indicated. The final evaluation of the MELT test includes two types of messages, \"PASS... Most of the line parameters correspond to the established criteria, no intervention is required.\" or \"FAIL... Multiple line parameters have exceeded the range, are above or below range. Check the parameters and take additional measurements!\"  
For verification of the mobile application's functionalities, we performed experiments and tests on several real deployed homogeneous symmetric lines utilized in real metallic access network infrastructure of one of Slovakia's telecom network operators. Testing and demonstration of the proposed application took place directly at the network operator side using a test software tool from Nokia (Alcatel-Lucent). Then, the test method was selected (MELT). The MELT test is possible to realize in two ways (testing collective and testing group parameters). The difference is contained in the output display. The standard MELT test procedure should not take more than 20 s from the start-up. After the MELT test, it is possible to view measured test parameter values and export them (CSV format). Examples of the Nokia Sample test software and MELT test parameters are presented in Figures 3 and 4. In Figure 3, the procedure for selecting the MELT option in the Nokia test software is shown. On the left side, the port for testing is selected and appropriate possibilities are displayed by the right mouse button. After the \"Actions\" option is confirmed, the \"Metallic Ended Line Test\" option offers two choices (Group Test and Collective Test) differing only in the output display.