VDC would be the abbreviation for Volt Direct Current which translated would volts direct current. The idea of ??this type is unidirectional current to the load. Direct current is normally produced by batteries, thermocouples, solar cells and a dynamo electric machine type. The direct current can flow in conductors such as wires, but may also flow through semiconductors, insulators ... In the image: 1 - current per pulse 2 - Direct Current (DC) 3 - Alternating Current (AC) 4 - Variable Current

The case MMF multimode fibers is when the core optical fiber is larger than the coating and it happens that a ray of light propagates through the fiber as multiple beams or modes. So the input and output have differences, this is also because many of the rays lose energy becoming heat. In multimode fibers the time dispersion and attenuation is greater than on other dand fiber. We show you a table for variations in multimode fiber.