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In general, intrabuilding power line noise can be considered to consist of continuous, relatively low level background noise punctuated by high level noise impulses. Background noise is typically Gaussian, [2] and its effects on communication performance are well understood. [3] In the case of impulse noise, its time-domain characteristics (amplitude, width and interarrival time) are very important to determine the influence on data communication systems. Chan and Donaldson [4] characterized noise impulses on PLC networks. They conclude:
- Impulse strength is typically more than 10 dB above the background noise level and can exceed 40 dB.
- Impulse frequency for the dominant impulse train is usually 120 Hz.
- Impulse width can vary up to a few percent of the impulse period for 120 Hz impulse noise.
- Because noise as well as wanted signal is subjected to attenuation, noise sources close to the receiver will have the greatest effect on the received noise structure, particularly when the network attenuation is large.
- Harmful effects of impulse noise on data communications systems can be expected.
Item 4 above bears significant consequences. It says that when a noise source is located close to a receiver, and when the signal is attenuated (across-phase communication, or attenuation caused by the combination of line impedance and the presence of low impedance loads along the communication link) a local noise source could make a receiver exceed its noise tolerance (signal to noise ratio), yielding erroneous received data.
References :
[2] H.J. Trussel and J.D. Wang, "The effect of hard limiters on signal detection in harmonic noise using adaptive noise cancellation", IEEE Trans. Pwr. Del., Vol. PWRD-1, pp. 73-78, Jan 1986.
[3] J.M. Wozencraft and I.M. Jacobs, "Principles of communication Engineering", New York : Wiley, 1965.
[4] M.H.L. Chan and R.W. Donaldson, "Amplitude, width and interarrival distributions for noise impulses on intra-building powerline communication networks",IEEE Trans. Electromagn. Compat. Vol. EMC-31, pp320-323, Aug 1989
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