A repeater for regenerating signals communicated along a telecommunication line uses a constellation providing a sufficiently high constellation density to ensure that regenerated signals are spectrally compatible. In one exemplary embodiment, such a repeater is configured to implement a method comprising the steps of: receiving first data signals from a first telecommunication line segment; demodulating the first data signals thereby recovering digital data using a constellation that provides a first constellation density; modulating second data signals with the digital data; transmitting the second data signals across a second telecommunication line segment that is bound within a cable; selecting a second constellation density for use in the modulating step such that the second data signals are spectrally compatible with other signals transmitted across a third telecommunication line segment bound within the cable, wherein the second constellation density is higher than the first constellation density.