Q53: What is the abnormity of the impedance?

A53: The impedance is a kind of electric index of the cables. It should be a constant in the cabling system. If the impedance is not a constant in the use, the phenomena of reflection will occur in the place where the impedance changes. The standard of DS100 and DS2000 the Fluke Company used could show the abnormity of the impedance through the default reflect value of 15%, ie, if the reflection signal goes beyond 15%, it will show that the impedance is in abnormity. Besides, DSP100/2000 could trace out the curve of the special impedance. The perfect curve should be a straight line. If the impedance goes in an abnormal way, there must be a wave crest or a trough in the curve. The wave crest shows that the figure of the impedance becomes bigger, while the trough shows the figure of the impedance becomes smaller.