A communication system 10 includes a head end 12. In order to provide increased measuring accuracy by improved temperature compensation, it is proposed, in the scope of the invention, that the evaluation instrument for the determination of the temperature prevailing in the test zone of the test element comprises an infrared detector. A pixel clock correction data synthesizing unit synthesizes a first selection signal, which is generated base on a time-series distribution of the pulses of each period defined by a first set of data, and a second selection signal, which is based on a time-series distribution of the pulses of each period defined by a second set of data, so as to generate the output selection signal. Calls may be made on an inter or intra LATA, region or state, nationwide or worldwide basis. The elastomeric adhesive holds the heat spreader in the appropriate position in relation to the substrate during injection of the molding material, and as the molding material hardens to form the mold cap the embedded heat spreader becomes fixed in the appropriate position in relation to the substrate.