Analysis of wave propagation in Time Domain Reflectometry circuit simulation model

Time Domain Reflectometry (TDR) has been commonly used for testing and diagnosis of faults along a transmission line. It involves the sending of an electrical pulse along a cable and using an oscilloscope to observe the reflected pulses. In this paper, the experimental set up based on Time Domain Reflectometry technique is developed using PSpice circuit simulation software. From the PSpice circuit simulation, the incident and reflected pulses at various nodes are obtained. In order to determine the wave propagation in a Test cable, the actual reflected pulse from the Test cable need to be evaluated. However, in practice the actual reflected pulses cannot be obtained directly from the Test cable but must be measured from the oscilloscope. Therefore, in this paper, the relationship between the actual reflected pulses from the Test cable to the reflected pulses measured from an oscilloscope is established by using the electrical circuit analysis and transmission line theory. Moreover, the characteristic impedance of the Test cable can be computed accurately from this relationship.