This part of IEC 60793 describes three methods for determining and measuring the modal bandwidth of multimode optical fibres (see IEC 60793-2-10, IEC 60793-30 series and IEC 60793-40 series). The baseband frequency response is directly in the frequency domain by determining the fibre response to a sinusoidaly modulated light source. The baseband respons can also be measured by observing the broadening of a narrow pulse of light. The calculated response is determined using differential mode delay (DMD) data. The three methods are:
- Method A - Time domain (pulse distortion) measurement
- Method B - Frequency-domain measurement
- Method C - Overfilled launch modal bandwidth calculated from differential mode delay (OMBc)