An electron beam source includes a base and a tip fixed to the base and extending from the base. The block of redundancy symbols of the current burst of the sequence is generated by calculating a sum of a series of coding values relating to a series of bursts, each coding value of the series of coding values being obtained by a respective coding function applied to the block of information symbols of the corresponding burst of the series of bursts. Each of the coupling lines connects two of the sensing cells.