Abstract—Power line communications (PLC) is a communication technology that uses a power line as a transmission medium. This study focuses on HD-PLC systems and proposes a system-specific period superimposed chart (SSP-SC) that visualizes the steady-state communication state using packet capture data. The conventional method of directly observing PLC signal waveforms in power lines using an oscilloscope makes it difficult to visualize signals over the long term. In addition, the number of burst signal inclusion packets is difficult to evaluate from the signal length, as the signal length varies depending on the communication environment. Furthermore, no methods have been proposed for PLCs to intuitively visualize communication conditions such as eye patterns and constellations in wireless communication. SSP-SC is a new visualization method for those problems, and its effectiveness is confirmed by comparison with conventional methods.