## 3 Evaluation of Melt Test Parameters and Analysis of DSL Service Provision
### Definition of Ranges for Evaluating Test Parameters  
The criteria for evaluating test parameters are built-up on the basis of available valid specifications [32; 33; 34; 35]. Since the applied research aim was carried out in a cooperation with the telecommunications network operator and service provider, the required implementation output, derived from evaluated test parameters in connection with their defined ranges and tolerances, is created and determined on the basis of DSL service demands, standard homogeneous symmetric line requirements and expert discussions. The evaluated and analyzed parameters provided by the MELT test output are foreign voltages (AC and DC) and capacity. Categories of the quantities for further processing as follows:  
* Direct Current (DC) voltages between sections RG, TR and TG,
* Alternating Current (AC) voltages between sections RG, TR and TG,
* Capacity (C) between sections RG, TR and TG.  
In [32], the Tip section may be referred to as \"wire A\", the Ring section as \"wire B\" and the Ground is designated for the reference point. For the correct evaluation of test parameters, it is necessary to define the allowed ranges and permitted tolerances of individual quantities. A possible value range consists of the allowed range, where the value of the quantity does not affect the quality of service, and permitted tolerances, where the value may (but does not necessarily) affect the quality of the transmitted service.  
The first quantity involves DC foreign voltages. Row 1 in Table 1 specifies the allowed range of DC foreign voltages between all sections [33].  
The permitted tolerances are defined for three possible cases, specifying the possible cause of the failure [34; 35]:  
* foreign electromotive force (Row 2 in Table 1),
* hazardous potential (Row 3 in Table 1),
* others (Row 4 in Table 1).  
Particular values of permissible tolerances for each case are presented in Rows 2, 3 and 4 in Table 1, correspondingly.  
The second quantity includes AC foreign voltages. In this case, the defined value ranges are the same as for DC voltages. The only difference is the defined rms voltage Vrms unit.  
The third quantity represents the C capacity. Its allowed values are introduced in Row 5 in Table 1. Important sections for analysis are the Ring-Ground and Tip-Ground sections. The Tip-Ring section is evaluated for the same defined range and does not affect the quality of service at excess.  
In this case, permitted tolerances are also defined (Row 6 in Table 1). In the first case, the value exceeds the limit range, and in the second, the value is below the limit range. In both cases, there may be a malfunction of the open wire, i.e., the short circuit. If a different  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**DC (RG, TR, TG)** & **Minimum Value** & **Maximum Value** \\ \hline Allowed range & 0 V & 49 V \\ \hline Permitted tolerance & 50 V & 199 V \\ \hline Permitted tolerance & 200 V & 201 V \\ \hline Permitted tolerance & \(-\)1 V & 0 V \\ \hline
**C (RG, TG, TR)** & **Minimum value** & **Maximum value** \\ \hline Allowed range & 0 nF & 1000 nF \\ \hline Permitted tolerance & 1000 nF & 1100 nF \\ \cline{2-3} \cl  
capacity value (other than within the permitted tolerance) occurs, the given wire is open (connected for a short time).