Coaxial cables, which are subjected to mechanical stresses such as shock, pulling force, physical pressure and torsion, generate electrical charges which are noticeable as disturbing currents or disturbing voltages on the cable. These disturbances, called 'mechanically induced noises' or 'cable microphony', are superimposed on the signals which the cable is carrying. They become significant in the case of low level-signals. In this article, the basics of cable microphony are briefly described, including piezoelectricity and triboelectricity, as are their effects on coaxial cables. A new measuring procedure, which has been developed by the Institute of Technology TH-Darmstadt, Germany, in cooperation with Bedea, is introduced. Using this procedure, cable microphony is measured with exactly defined mechanical stress and good reproducibility by measuring the electrical charge generated by the cable.
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