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352-001 · Question #786
352-001 Question #786: Real Exam Question with Answer & Explanation
The correct answer is D: shares the same transmission window as DWDM. CWDM's wavelength range overlaps with the DWDM transmission window in the C-band, and passive CWDM mux/demux devices use optical thin-film filters that require no electrical power.
Question
Which two descriptions of CWDM are true? (Choose two)
Options
- Atypically used over long distances, but requires optical amplification
- Buses the 850nm band
- Callows up to 32 optical earners to be multiplexed onto a single fiber
- Dshares the same transmission window as DWDM
- EPassive CWDM devices require no electrical power
Explanation
CWDM's wavelength range overlaps with the DWDM transmission window in the C-band, and passive CWDM mux/demux devices use optical thin-film filters that require no electrical power.
Common mistakes.
- A. CWDM is designed for short to medium distances (typically up to 80km) and does not require optical amplification; it is DWDM that is used over long-haul distances and requires EDFA amplifiers.
- B. CWDM operates in the 1270nm to 1610nm range; the 850nm band is used by short-reach multimode fiber transceivers (such as 1000BASE-SX), which are unrelated to CWDM.
- C. CWDM supports a maximum of 18 channels with 20nm channel spacing; it is DWDM that achieves 32, 80, or more channels using much tighter 0.8nm or 0.4nm spacing.
Concept tested. CWDM channel capacity and passive device characteristics
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