Mode Conditioning Patch Cable FAQ
Mode Conditioning Patch Cable, or Mode Conditioning Patchcord (MCP), is duplex multimode patch cable that has a small length of single mode fi ber at the start of the transmission length. The basic principle behind the MCP is to launch laser into the small section of single mode fiber. The other end of the single mode fi ber is coupled to the multimode section of the MCP with the off set from the center of the multimode fiber.
The MCP patch cord is required with -LX or longwave Gigabit Ethernet Transceivers that use both single mode and multimode fibers. When launching into multimode fiber, the transceiver can generate multiple signals that causes Differential Mode Delay (DMD) which can severly limit transmission distances. A mode conditioning cable removes these multiple signals, eliminating problems at the receiver end.
Using mode conditioning patch cable is not difficult, but there are also some notes that we should keep in mind. Here are some frequently-asked questions about mode conditioning patch cable for you.
1. When & Where is Mode Conditioning Patch Cable Needed?
- When using Gigabit 1000BASE-LX (or 10-Gigabit Ethernet 10GBASE-LRM and 10GBASE-LX4) equipment with existing multimode fiber cable plant. 1000BASE-LX is specified to work over a distance of up to 5 km over 9µm single-mode fiber. But 1000BASE-LX can also run over multi-mode fiber with a maximum segment length of 550 m.
- For any link distance greater than 300 m, the use of a special launch mode conditioning patch cable may be required.
2. How does Mode Conditioning Patch Cable Work?
Answer: Mode conditioning patch cable launches the laser at a precise offset from the center of the multimode fiber. This causes the laser to spread across the diameter of the fiber core, reducing the effect known as Differential Mode Delay (DMD) which occurs when the laser couples onto only a small number of available modes in multimode fiber.
3. Why should Mode Conditioning Patch Cable be ordered in Pairs?
Answer: Mode conditioning patch cables are normally used in pairs. That means that one at each end to connect the equipment to the cable plant. So then these cables are usually ordered in even numbers. The usual reason why someone may order one cable is so they may keep it as a spare.
4. How should Mode Conditioning Patch Cable be Connected?
Answer: If Gigabit 1000BASE-LX switch is equipped with SC or LC connectors, the yellow leg (single mode) of the cable should be connected to the transmit side, and the orange leg (multimode) to the receive side of the equipment.
5. Do all Multimode Fiber Types Require Mode Conditioning?
Answer: Some manufacturers of the newer "high end" multimode fibers claim that that their premium line cables will not require mode conditioning.
6. When holding the yellow Single Mode Cable up to a Light, the Light does not Come Through on the Other Side. Does This Indicate that it is a Defective Cable?
Answer: The core of the single mode cable is so small than it does not gather enough light for it to be visible without a microscope on the other side. This is a normal condition for any single mode cable.
7. Can Mode Conditioning Patch Cable be used to Convert Single Mode to Multimode or Vice Versa?
Answer: No. Conversions of multimode and single mode require Fiber to Fiber Media Converters.
