Cable and Antenna Test Mode
R&S
®
Cable Rider ZPH
103
User Manual 1321.0950.02 ─ 03
Figure 7-3: Reflection measurement
You can perform reflection measurements on the complete system or on individual
components of the system. If you measure while two or more system components are
connected, the results of the reflection measurement are an aggregate over these
components. Therefore you can only see the aggregated magnitude of the reflected
power in a specified frequency range.
To draw conclusions about which component is affected and to determine the location
of the fault, you need to perform further analysis using other measurements.
7.1.2 Distance to Fault Measurements
The distance to fault (DTF) measurement determines the exact location of possible
faults in a transmission system. If you connect the end of the cable to the R&S Cable
Rider ZPH, the DTF measurement shows you the exact distance to the fault (in meter
or feet), regardless by what the fault is caused. In addition, the measurement shows
the degree of the fault in dB. From this information, you can determine the component
that has the fault and its seriousness.
In order to determine the distance to a cable fault, the R&S Cable Rider ZPH measures
the reflections of the cable under test in the frequency domain. The R&S Cable Rider
ZPH first determines the magnitude of the reflections for a particular frequency by com-
paring the phase of the reflected signal and a reference signal created by the signal
source. It then performs an inverse fast fourier transformation (IFFT) on the signal that
has been received. In combination with the characteristics of the cable model, the R&S
Cable Rider ZPH is able to determine the distance the reflections have been traveling.
Because of its sensitivity by first measuring in the frequency domain and subsequent
IFFT, the measurement is able to locate faults in a cable accurately. To keep this accu-
racy, the R&S Cable Rider ZPH also accounts for any attenuation that occurs over dis-
tance in a cable.
The DTF measurement can be performed in the following measurement formats:
●
Magnitude (return loss in dB)
●
SWR
1. Press the MEAS key.
2. Select the "DTF" softkey.
Performing Cable and Antenna Measurements
