Quiz 2 answers

Quiz 2 answers - 50GHz apart at approximately 1550nm? df c...

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Quiz 2 Answers: 1. A NRZ system uses a 12GHz transmitter and receiver and has a 10km fibre link with a D = -18ps/nm/km. The transmitter has a spectral width of 0.1nm. What is the maximum transmission rate? Transmitter/Receiver rise time = 0.35/12e9 = 29.2ps Fibre rise time = 18 x 10 x 0.1 = 18ps System rise time = sqrt (18^2 + 29.2^2 +29.2^2) = 45ps Max Bit Rate = 0.7/45 = 15.6Gb/s 2. A Gaussian pulse with a width of 5ps is past through a 5km fibre with a dispersion parameter β 2 =20ps 2 /km. What is the output pulse width? Ld = 5^2/20 = 1.25km T1 = T0 x (1 + (z/Ld) 2 ) 1/2 = 5 x (1 + (5/1.25) 2 ) 1/2 = 20.6ps 3. What is the frequency of an optical carrier at 1552nm? f = c / lambda = 3x10 8 / 1552x10 -9 = 193.299 THz 4. What is the wavelength separation in nanometers of two channels which are
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Unformatted text preview: 50GHz apart at approximately 1550nm? df c d 2 = = ((1550x10-9 ) 2 /3x10 8 ) x 50x10 9 = 0.4nm (n.b. this formula can be found be differentiating f=c/ with respect to and re-arranging for d , it can only be used for small d or df (i.e <10nm or 1250GHz) 5. What is the peak-to-peak voltage of a 10dBm electrical signal into a 50 load? P = 10 (10dBm/10) = 10mW Vrms = (P x R) 1/2 = (0.01 x 50) 1/2 = 0.707V Vpp = Vrms x 2 1/2 x 2 = 2V 6. A -13dBm optical signal is incident on a photodiode with a response of 0.6A/W, this is followed by a transimpedance amplifier with a transimpedance of 11k , what is the output voltage? P = 10 (-13/10) = 50uW I = P x R = 50uW x 0.6A/W = 30uA V = R x I = 11k x 30uA = 0.33V...
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Quiz 2 answers - 50GHz apart at approximately 1550nm? df c...

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