# Modal bandwidth

Modal Bandwidth, in the discipline of telecommunications, refers to the maximum signaling rate for a given distance or – the other way around – the maximum distance for a given signaling rate. The signaling rate can typically be measured in MHz, and the modal bandwidth is expressed as the product MHz·km. For a cable with a certain modal bandwidth, the maximum frequency can be doubled when the distance is halved and vice versa.

The Modal Bandwidth is derived from the dispersion of the fiber and the spectral linewidth of the laser.

${\displaystyle BR\cdot L={\dfrac {1}{D_{Chrom}\cdot \Delta \lambda }}}$

Modal bandwidth is sometimes referred to as EMBc.