A method comprising: modulating a plurality of synchronized signals by an orthogonal probe sequence, OPS, to generate a plurality of modulated synchronized signals, wherein the OPS comprises a zero element, 0-element, column that indicates a start or an end of the OPS, the OPS is a matrix comprising a probe sequence of each subscriber lines as its each row, each probe sequence has the same length as the probe sequence of other subscriber lines but orthogonal to each one of them; and concurrently transmitting, using one or more transmitters, the plurality of modulated synchronized signals over a duration of a number of discrete multi-tone, DMT, symbols, wherein each of the plurality of modulated synchronized signals is intended for one of a plurality of receivers that are remotely coupled to the one or more transmitters via a vectored group of subscriber lines, and wherein the 0-element column causes all of the plurality of modulated synchronized signals to have a zero-amplitude during a first or a last of the DMT symbols; wherein the 0-element column is a first column or a last column of the OPS, wherein the first column containing only 0-elements indicates the start of the OPS, wherein the last column containing only 0-elements indicates the end of the OPS, wherein the OPS contains no 0-element in any other column except the first column or the last column; wherein the zero-amplitude of the plurality of synchronizing signals leads to zero far end signal and zero far end crosstalk (FEXT) among the vectored group of subscriber lines in the first or the last of the DMT symbols; wherein the 0-element column comprises 0-elements, wherein the OPS further comprises plus one, +1, elements and minus one, -1, elements located in other columns except the 0-element column, wherein during the modulation each DMT symbol is multiplied by one of the +1 elements, -1 elements, and 0-elements that corresponds to the DMT symbol, wherein one of a +1 element and a -1 element leaves the DMT symbol intact and the other one reverses a phase of the DMT symbol during the modulation, and wherein a 0-element renders the DMT symbol to have the zero-amplitude. modulating a plurality of synchronized signals by an orthogonal probe sequence, OPS, to generate a plurality of modulated synchronized signals, wherein the OPS comprises a zero element, 0-element, column that indicates a start or an end of the OPS, the OPS is a matrix comprising a probe sequence of each subscriber lines as its each row, each probe sequence has the same length as the probe sequence of other subscriber lines but orthogonal to each one of them; and concurrently transmitting, using one or more transmitters, the plurality of modulated synchronized signals over a duration of a number of discrete multi-tone, DMT, symbols, wherein each of the plurality of modulated synchronized signals is intended for one of a plurality of receivers that are remotely coupled to the one or more transmitters via a vectored group of subscriber lines, and wherein the 0-element column causes all of the plurality of modulated synchronized signals to have a zero-amplitude during a first or a last of the DMT symbols; wherein the 0-element column is a first column or a last column of the OPS, wherein the first column containing only 0-elements indicates the start of the OPS, wherein the last column containing only 0-elements indicates the end of the OPS, wherein the OPS contains no 0-element in any other column except the first column or the last column; wherein the zero-amplitude of the plurality of synchronizing signals leads to zero far end signal and zero far end crosstalk (FEXT) among the vectored group of subscriber lines in the first or the last of the DMT symbols; wherein the 0-element column comprises 0-elements, wherein the OPS further comprises plus one, +1, elements and minus one, -1, elements located in other columns except the 0-element column, wherein during the modulation each DMT symbol is multiplied by one of the +1 elements, -1 elements, and 0-elements that corresponds to the DMT symbol, wherein one of a +1 element and a -1 element leaves the DMT symbol intact and the other one reverses a phase of the DMT symbol during the modulation, and wherein a 0-element renders the DMT symbol to have the zero-amplitude.