When performing device-independent OTDR measurements for checking fibre-optic links, launch fibres and/or receive fibres are required to bridge the device’s dead zones and to comply with IEC measurement specifications. For most OTDRs a launch fibre is the only possibility to include the first connector on the link in the measurement. By connecting a receive fibre the connector at the end of the link under test is additionally included. Tester manufacturers recommend different lengths for launch and receive fibres in order to avoid ghost reflections.