Characterization of PowerLine Communications Disturbed by Impulsive Noise Anderson Gusmão de Lima Universidade Presbiteriana Mackenzie São Paulo – São Paulo - Brazil

Noise on PLC - History PLC was created, based on Powerline Carrier; Dr. Paul Brown, of the Norweb Communication, starts doing tests with digital communication over the powerline; Beginning of studies of the noise interference and of methods of solve this problem;

PLC - Introduction Consists of impressing a modulated signal on the transmission line, with the low-frequency power signal; Applied on low, medium and high voltage transmission lines; Frequency and data rate vary according to the application.

Tests Characteristics Quadrature Amplitude Modulation (QAM); Wavelet Orthogonal Frequency Division Multiplexing (WOFDM); Band from 2 to 30 MHz (High Frequency); Panasonic’s BL-PA100A modem; Tektronics’ DPO4104 oscilloscope.

Objectives Obtain a mathematical model for the influence of the Impulsive Noise over the power grid, affecting the PLC signal; Develop tools that ensure better transmissions.

Impulsive Noise Duration of few milliseconds; Unpredictable occurrence. Natural or artificial source; Occurs in two ways: – Single pulse; – Burst.

Impulsive Noise Its model has two main categories: Temporal: – Maximum Amplitude (V); – Length (s); – Inter Arrival Time (IAT). Spectral: – Autocorrelation; – Power Spectral Density (PSD).

Modelling Serie expansion: Sum of exponentially dumped cosines: – at several frequencies (α 1, α 2,...); – with several exponential decays (β 1, β 2,...). Each cosine has a normalized amplitude (A 1, A 2,...)

Results Only three components represents more than three quarters of the generated noise. (Mann, 2002) The obtained noise expression is: The Power Spectral Density will be:

Results – Example of R(t)

Results – Example of S(ω)

Pratical Tests Real powerline network; Impulsive noise generated by the use of an electric drill motor with brush; Ativating the drill cause the lowering of the speed of the transference.

Pratical Tests

Considerations Model of Single Impulse; Burst being developed; α-Stable distribution; Proposal of filters for cancellation of the Noise.

Contributions Good aproximation to single impulses; Median Filter in serie with a Mobile Media Filter applied to a real burst noise over an artificial sinusoid with frequency of 60Hz, simulating the noise on the powerline channel.

Filters Window with length three; 0.1 ms of the signal, simulating the 60 Hz channel; Modulation wasn’t considered; 20 iterations.

Filters

Conclusions Accurate Models, to determined characteristics; The signal was less affected by the noises with the filters.

Any doubts?

References A. Majumder and J. Caffery, Jr., Power line communications: an overview, IEEE Potentials, 2004 V. Degardin, M. Lienard, A. Zeddam, et al, Classification and Characterization for Impulsive Noise on Indoor Power Line used for Data Communications, IEEE Transactions on Consumer Electronics, vol. 48, pp , November I. Mann, S. McLaughlin, W. Henkel, et al, Impulsive Generation with Appropriate Amplitude, Length, Inter Arrival and Spectral Characteristics, IEEE Journal on Selected Areas in Communications, vol. 20 pp , June E. Hodgson, L. Resende, Propose of an Impulsive Noise Modelling and Simulation System for the PLC Channel, Dissertation presented to UFSC pp , December P. G. Georgiou, P. Tsakalides, C. Kyriakakis, Alpha-Stable Modeling of Noise and Robust Time- Delay Estimation in the Presence of Impulsive Noise, IEEE Transactions on Multimedia Vol. 1, No. 3, September 1999.

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