The accuracy of the propagation velocity (vp) value will determine the accuracy of the location of the discontinuity. A ± 5% error in the vp value
will affect the distance accuracy accordingly and the end of the 80 ft cable could show up
anywhere between 76 and 84 ft . Even if the vp value is copied out of the manufacturer’s
datasheet, there could still be some discrepancies between the interpreted and actual distance
discontinuities. This is a result of adding all the components in the system. Common base
station systems can include a main feed line, feed line jumper, adapters, top jumpers and
even though the main feed line contributes with the largest amount, the velocity of the signal
through the other parts of the system could be different.