Task 3^th

1.

–        What are the energies in electron volts (eV) of light at wavelength 850, 1310, 1490, 1550 nano meters?

–        Consider A 1-nano second pulse with a 100 nW amplitube at ecah of these wavelengths. How many Photons are in such a puls at each wavelengths?

2. Three sine wave have the following periods: 25 mikro second,250 nano second, 125 piko second. What are their frequencies.

3. Consider two signal have the same frequency. When the amplitude aof the first signal is at its maximum, the amplitude of the second signal is at its half maximum from the zero level. What is the phase shift betwen the two signals?

4.

–        Convert the following absolute power gain to decibel power gain: 10^-3 , 0,3 , 1, 4, 10, 100, 50, 2ⁿ.

–        Convert the following decibel powergain to absolute power gain : – 30 dB, 0dB, 13dB, 30dB, 10n dB.

5. A signal travel from point A to point B.

–        If the signal power is 1.0 mW at point A and 0.125 mW at point B, what is the attenuation in dB?

–        What is the signal power at poin B if the attenuation is 15 dB?

6. A 50-Km long optical fiber has a total attenuation of 24 dB. If 500 mikro W of optical power get launched into the fiber, what is the output optical power level in dBM and mikro Watt?

7.

–        At the lowest TDM level of digital service scheme, 24 chanel of 64 kb/s each are multiplexed into a 1.5544 Mb/s DS1 chanel. How how much is the overhead that is added?

–        The next higer multiplexed level, the DS2 rate, is 6.312 Mb/s. How many DS1 channel can be accommodate in the DS2 rate and what is the ocerhead?

Answer :

1. Ev =(1239,84187 V nm)/λ

(a)

(b)

2. f =1/T

3. …

4. dB =10 log P1/P2

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