The paper proposes an approach to investigate the fine structure of the voltages circulating in the industrial network within the range of 300 kHz-20 MHz, which serves to do some measurements of real lines in real operating mode. It is shown that the interferences can be divided into basic- with spectral density changing slowly with frequency alteration and narrow-band (frequency-pulse). It is also indicated that the frequency concentrated interferences occupy usually 1-5% of the frequency range studied and their intensity is deeply modulated with the doubled frequency of the power supply voltage. There are areas with distinctly expressed low interferences around the zero transitions. The study is motivated by the search for sophisticated methods of high-speed data exchange through the power network.
In-building power lines have been considered as a medium for high speed data transmission for applications like home networking and Internet access. Frequency selectivity and time variation of this medium in addition to the high level of narrow-band and impulsive interference makes multi-carrier modulation, and especially its popular variant discrete multitone (DMT), an attractive modulation candidate for this application. This paper presents the results of our measurements of the high frequency characteristics of ordinary in-building power lines, as well as simulation results of a DMT transceiver system in an in-building power line environment.
[1] The origins of rip current pulsations within the infragravity frequency band (0.004–0.04 Hz) are determined from measurements made with arrays of colocated pressure and velocity sensors deployed on a beach with persistent rip current channels. The observations indicate significant energy in cross-shore infragravity velocities that varies spatially in the alongshore due to the presence of rip channels. Infragravity velocities are smaller within the rip channel than on the shore-connected shoal owing to differences in water depth. Rip current pulsations at infragravity frequencies are linked to standing infragravity motions but not to the ponding and subsequent release of water by wave group pumping.