Given the formula: (Fiber Attenuation * Km) + (Splice Attenuation * # of Splices) + (Connector Attenuation * # of Connectors) + (Optical Fiber or OADM) + Buffer(Fiber aging)) With regard to SONET/SDH optical calculations, what will the given formula provide?（）

多项选择题What three in combination are factors that can cause four-wave mixing in fiber-optic cables? （）(Choose three.)

A. low optical power
B. high optical power
C. few optical channels
D. many optical channels
E. low chromatic dispersion
F. high chromatic dispersion
G. too much power differential in the optical channels

单项选择题Why are the 1300 nm and 1550 nm regions of the fiber spectrum primarily used for optical communications?（）

A. They are both regions of lowest loss.
B. They are both regions of low reflections.
C. They are both regions of low index of refraction.
D. They are both regions of low chromatic dispersion.
E. They are both regions of low Polarization Mode Dispersion (PMD).

单项选择题What is an advantage of an externally modulated laser over a directly modulated laser?（）

A. lower cost
B. higher chirp
C. easier to manufacture
D. higher dispersion tolerance
E. higher optical signal-to-noise ratio

单项选择题What is the difference between the transmitted power and the sensitivity of the receiver?（）

A. OSNR
B. dispersion
C. attenuation
D. power budget
E. amplifier spacing
F. four wave mixing

多项选择题Which three technologies are used to reduce chromatic dispersion accumulation in fiber-optic transmission systems? （）(Choose three.)

A. PIN photodiodes
B. zero-chirped lasers
C. Erbium-doped fiber amplifiers
D. dispersion compensating fiber
E. dispersion compensating Bragg grating