Spread Spectrum Time-Domain Reflectometry

Sequence time-domain reflectometry (STDR) and spread spectrum time-domain reflectometry (SSTDR) use pseudo-noise (PN) codes or modulated PN codes to detect, locate, and diagnose faults or measure impedance. The inherent noise immunity and orthogonality with other PN codes, allows S/SSTDR, to be used on live/energized electrical systems while still online. They can also measure multiple channels in parallel using different orthogonal PN codes. In this chapter, we describe the theory, analysis algorithms, implementation strategies, and applications and propose future directions for this work.