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 of a multimode fiber is determined from the optical output power frequency spectrum. The frequency at which the amplitude drops three decibels (dB) relative to the zero frequency component of the fiber is defined as the −3 dB bandwidth (or modal bandwidth) of the fiber.
Modal bandwidth is sometimes referred to as EMBc.