RigExpert AA-230 ZOOM
21.
Software manual
20/03/2019
(Top)
Time domain reflectometer (TDR) mode
This mode displays impulse response and step response graphs which show how
electromagnetic wave reflects from discontinuities in a cable.
Additionally, a tool tip near the cursor shows estimated value of the impedance of
a cable at the corresponding distance.
This will let you know if your cable is in a good or a bad condition.
For best results, perform a scan over the full frequency range with 1000 or more
points.
Make sure the characteristic impedance and the velocity factor of the cable are
set in the
Settings
–
Cable
parameters menu.
This will let you see the exact distance to the discontinuity.
For TDR measurements, it is not important if the cable ends with antenna, open
circuit or short circuit.
Calibration mode
Although RigExpert analyzers are designed to provide suitable precision without
any cali
bration, a simple “open
-short-
load” calibration method may be used to
improve the result.
Moreover, this method may be used to remove the effects of a cable, so accurate
measurements at the far end of the cable become possible.
For this method, three cali
bration standards are required: an “open”, a “short”
and a “load” (usually, a 50
-Ohm load).
For better results, these standards should be of a good quality.
Additionally, physical length of all loads should be the same.
