Prediction of Structural Return Loss (SRL)
As standard, powerful digital signal processors are used in all SIKORA gauges, such as the CENTERVIEW 8000, LASER Series 2000, LASER Series 6000 and CAPACITANCE 2000. Due to the processing power of the gauges, the integration of a digital FFT spectrum analyzer and Structural Return Loss prediction directly within the gauge are possible. The analysis takes place where diameter, eccentricity or cable capacitance measuring values with high amplitude resolution as well as high precision at minimal value noise are available. A problematic (usually analogue) transfer of sensitive single measuring values to external FFT and SRL analysis systems is not necessary.
The mostly used method for quality control of data and high frequency cables is the SRL measurement of a cable length as a function of frequency within the range of signal frequencies where the cable is specified for. The Structural Return Loss represents the relation – specified in dB – between the fed signal and the reflected signal parts along the complete cable length.
To optimize the cable quality and to reduce the scrap quantity, it is desirable to detect effects of periodical irregularities towards the later Structural Return Loss of the final cable early in the production process.
The prompt SRL prediction during the extrusion of a cable or a wire from measured short-term data, such as cable capacitance or diameter measuring values, provides according information. Especially regarding the online demands, this prediction method is significantly based on the above mentioned Fast Fourier Transformation according to the FFT algorithm.