Implementation of a gap recorder for measuring impulsive noise error distributions in Power Line Communications using the Fritchman model

On the PLC channel, noise is generated by electrical loads and by radiated disturbances from the environment. In the frequency range of 9-140 KHz, it is dominated by narrowband interferences and impulsive noise. Impulsive noise is caused by on/off switching events and is different from frequently occurring periodic events. For instance, we have vacuum cleaners; hand-held drilling machines; Switch Mode Power Supply (SMPS) and heaters which are used daily in the network and introduce a lot of impulsive noise into the channel. This leads to an enormous loss in the capacity, as well as a decrease in the error rate performance. Impulsive noise can cause bit and bust errors in PLC. The bit error rate represents an important first order statistic of the data channel, but does not contain information about how the errors are distributed. In this paper, the distribution of errors at the output of a narrowband modem is investigated using gap recording. A gap recorder has been implemented for setting up a stochastic model. The Fritchman Markov model has been investigated to model the distribution of random impulsive events. Values of the model parameters were obtained by analysing the distributions of the lengths of error gaps (error free intervals). Two sets of measurements have been taken, one in an office building and the other in a residential house.