The short jumper dsx-8000 test is normal, but the dsx-5000 test has no length display?

According to customer feedback , They produce jumpers , You can go through DSX-8000 Cable certification Tester , But I can't live DSX-5000 Cable tester ？ What is the reason for this ？
See the measured figure below ：

As can be seen from the figure above , Each parameter has , Only there is no length display .


Use the same line DTX-1800 Test or DSX-8000 Can display its length .
Why is that ？
Because there is no official case , It can only be judged by personal experience , It is estimated that the loop resistance is unbalanced or too large .
How can we improve the loop resistance ？ The impedance matching degree of crystal head and cable is not good , Is the most likely reason .
Next, hit the crystal head again .
Sure enough, take a look at the test

Conclusion ： The impedance matching between the crystal head and the cable is unbalanced, resulting in . The sampling point estimates of the two are also different .