An OTDR launch cable, which connects the OTDR to the link-under-test, discloses the insertion loss and reflectance of the near-end connection. It is used to create the proper conditions for testing another similar optical fiber for faults. This method avoids undesirable variations in loss and distance measurements. A launch fiber will help to overcome the blind spot or Dead Zone of an OTDR brought about by high launch power or faults near the launch end of the fiber.
