Figure 4 shows a representative COAX Trace for this condition. The reflections should occur at the sum of the length of the input and respective output branches. There should be one and only one reflection for each branch. Only the reflections off the un-terminated ends of the output branches will be seen. Therefore, when hooked into a 75 ohm cable system there will be little to no reflection at the splitter since there isnt an impedance change. What will the COAX Trace show if splitter is a high quality type?Īn ideal or high quality splitter has the characteristic of looking like a 75 ohm impedance device across a wide frequency range on input and output ports. L2 and 元 are connected to the output ports of the splitter and are un-terminated. It has three branches of lengths L1, L2 and 元 respectively. With this simple knowledge, a user can view the TDR trace and determine if there are impedance mismatches due to a splitter and how many times a signal is split.Ĭonsider the following example of coax cabling which has a 2 way splitter being tested by a CableIQ (Figure 2). The size of the reflection is a function of the size of the impedance change. If the change in impedance is lower then the reflection is negative. If the impedance change goes higher, for example an open circuit, the reflection is positive. TDR is like radar and signals reflect off each point where there is an impedance change. The CableIQ implements a TDR (Time Domain Reflectometry) like technology that allows it to determine the location of impedance changes. The TDR trace will contain information to generally assess the quality of the splitter and how many times it is split. Once a splitter has been detected, the user can inspect the COAX TDR Trace to look at the reflections on the coax run and determine other information. The CableIQ running in Coax Discover Mode can detect the presence of a splitter in a coax run and alert the user. However, the technology implemented in the CableIQ now allows this information to easily be determined. In the past, detecting the presence of splitters, their quality and the number of splits has been very difficult to do without specialized test equipment. Yes, the CableIQ can detect the presences of splitters in a coax system, but not always show their location (output branches must be un-terminated). Can the CableIQ detect the presence of splitters?
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