Multiplexing Basics

When you need to carve up an expensive resource (such as an active fiber route) into pieces, multiplexing is the way to go. What is multiplexing, you may ask? It's the process by which multiple signals are combined into a single signal, then split back into pieces upon arrival.

There are lots of types of multiplexing. The most simple is space division where the signal carriers are literally held separate by some kind of insulator (like CAT5 or telephone wire.) Time division multiplexing involves using a timer on either end to determine which signal the carrier is carrying. Core-division multiplexing (CDM) uses a code followed by data to specify which signal is being carried. Finally, frequency-division multiplexing (or in the fiber optic world, wavelength division multiplexing) involves sending signals over several distinct frequency ranges over a carrier.

The easiest way to think about this is in terms of light. At one end of a  fiber optic cable you have a lens that takes many colors of light and combines them into high energy white light. That white light is sent to a prism at the other end of the fiber which splits the white light back up into it's constituent colors. If the red light at the beginning of the fiber blinks in a certain pattern, the red light at the far end will also blink without interfering with the other colors (wavelengths.)

The device responsible for combining the signal is often called a MUX while the one responsible for splitting it apart is called a DEMUX. In two way communications a MUX/DEMUX pair is required at each endpoint so that communications can be sent and received.

WDM (wave-division multiplexing) is further broken down into two flavors, CWDM or Coarse WDM and DWDM or Dense WDM. In Coarse WDM fewer signals are combined onto the fiber and they are spaced farther apart. In DWDM more signals can be combined resulting in increased hardware and system design complexity and higher costs. Depending on the system needs CWDM and DWDM are both viable options.

I hope that helps explain why multiplexing is such an important part of fiber optic communications!

If you're interested in getting the most out of your fiber by using WDM, please check our website or contact Mike Soron for more information.

Product Spotlight

The NOYES OFL280 FlexTester is a hand-held, single-mode OTDR available in two- and three-wavelength models, all equipped with optical power meter, light source, and visual fault-locator. With best in class dead zones and excellent dynamic range, the OFL280 FlexTester can test point-to-point fibers up to 150 km or PONs with split ratios up to1x64. An available live fiber model can also measure FTTx power levels at 1490 and 1550 nm and fault-locate in-service customer fibers.

Hot Deal

Ask A Fiber Expert

Last Month's Puzzler: Why is aluminum oxide abrasives recommended for polishing ceramic ferules in connectors? For anybody who was stumped last month, here's the answer to the previous puzzler. The curved polishes on ceramic ferules – particularly UPC finishes – must be preserved in the polishing process. Aluminum oxide abrasives are not going to abrade the ceramic ferule, yet will polish the glass fiber. This protects the integrity of the ferule finish.

??? Solve & Win Puzzle ???

Solve this month's FIBER CHALLENGE question and enter a drawing to win some FREE Fiber Optic SWAG!* No entries will be accepted after 5/20/2011. Answer the following question and simply e-mail the solution to marketing@fiberoptic.com for a chance to win! What is caused by the differential arrival time of the different polarization modes (horizontal and vertical) transmitted into a fiber (by its birefringence)? Don't know the answer? Don't forget that FiberOptic.com offers comprehensive introductory & advanced fiber optic training courses! Visit www.theFiberSchool.com. *There are a limited number of winners each month. Due to international shipping costs, participants outside the United States will receive their prize along with their next order from FiberOptic.com

Featured Products

LANSCOPE NETWORK ANALYZER - Gigabit BlackBox Network Testers Featured Item Provides complete inline packet inspection. BB-18841 $1,895.00 1000MHz Category 7/ISO Class FA LAN... Ideal Industries Network Testers Copper Cable Certifier 33-993 $7,894.74 FiberTEK FDX Dual MM LED/SM Test Kit Ideal Industries Network Testers Fiber Heads for the LanTek II Cable Certifier Fibre Optic certification to TSB Tier 1 standards using the LanTEK® II cable certifier platform. 33-990-FA04 $9,621.64 SECURITEST PRO Ideal Industries Network Testers CCTV Testing Tool FeaturesSeven Essential CCTV Tools - Combines a CCTV video tester, PTZ camera controller, Digital Multi-Meter, UTP cable tester, video test pattern generator, PTZ protocol analyzer and camera programmer in a single compact package.Save Time & Money - Test, aim, focus and program cameras when working alone. 33-892 $849.00 PRO-730 Core Alignment Fusion Splicer Precision Rated Optics Fusion Splicers Best Price FiberOptic.com's best priced Core Alignment Splicer. PRO-730 $8,995.00 Type-39 (Batt., Cleaver, Stripper) Sumitomo Fusion Splicers $14750 - $1000 Off! Sumitomo's Type-39 FastCat Core Alignment Fusion splicer is the industry's first splicer to feature a Dual-Automatic Heater System featuring Auto Start Heater and Auto Start Splice functions - making the FastCat the fastest splicer available today. TYPE-39-KIT2 $15,750.00 Electrode Cleaning Disc Fitel Accessories Extend the Life of Electrodes D5111 $20.00

Read the FiberOptic.com privacy policy.