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352-001 · Question #157
352-001 Question #157: Real Exam Question with Answer & Explanation
The correct answer is C: shares the same transmission window as DWDM. CWDM uses passive optical devices requiring no electrical power, and its wavelength range overlaps with DWDM's transmission window.
Question
A junior engineer is implementing one of your optical designs and asks about CWDM (Coarse Wavelength Division Multiplexing). Which two features describe CWDM? (Choose two.)
Options
- Atypically used over long distances, but requires optical amplification
- Ballows up to 32 optical carriers to be multiplexed onto a single fiber
- Cshares the same transmission window as DWDM
- Duses the 850-nm band
- EPassive CWDM devices require no electrical power.
Explanation
CWDM uses passive optical devices requiring no electrical power, and its wavelength range overlaps with DWDM's transmission window.
Common mistakes.
- A. CWDM is designed for shorter distances (typically up to 80 km) and cannot use erbium-doped fiber amplifiers (EDFAs) for optical amplification because its wide channel spacing extends outside the EDFA gain band.
- B. CWDM supports up to 18 wavelength channels (1270-1610 nm at 20 nm spacing), not 32; it is DWDM that supports 32 or more channels using much tighter 0.8 nm or narrower spacing.
- D. The 850 nm band is used for short-reach multimode fiber applications such as 10GBase-SR; CWDM operates in the 1270-1610 nm range on single-mode fiber.
Concept tested. CWDM wavelength range and passive device characteristics
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