Problems And Exercises Mpk
1 Show diagrammatically the ''common volume'' and ''scatter angle.''
2 There are two types of fading encountered on tropospheric scatter links. Define and name the types of distributions (statistical distributions of fade events) encountered.
3 Given smooth earth conditions and site elevations of transmitter and receiver of 150 and 250 m above MSL, respectively, what are the takeoff angles at the transmitter and receiver sites?
4 Given sea level refractivity of 310, calculate surface refractivity for a tropo link where the transmitter and receiver sites are 1221 and 1875 m above MSL, respectively.
5 A radiolink 200 km long is to be installed in the eastern United States; the sea level refractivity is 320. The transmitter site is 158 m above MSL and the receiver site is 315 m above MSL. Allow 11 m to antenna centers at each end. The altitude of the transmitter horizon is 330 m and the receiver horizon is 490 m, and the distances to each horizon are 60 and 30 km, respectively. Assume hst = hts = 169 m and hsr = hrs = 326 m. Calculate the effective earth radius.
6 Using the information given in question 5, calculate the horizon takeoff angles.
7 As in question 6, calculate the effective antenna heights assuming linear increments in altitude.
8 As in question 6, calculate the angular distance (or scatter angle).
9 Using information developed in questions 5-8, with an operational frequency of 1800 MHz, calculate the basic transmission loss Lbsr.
10 From question 9, calculate the long-term median transmission loss Ln.
11 From question 10, the service probability factor is 95%; compute the path loss for a time availability of 99.9%.
12 Assuming 60-ft antennas, calculate the aperture-to-medium coupling loss using both methods given in this chapter.
13 Using information from questions 11 and 12, define the parameters of a baseline system that uses quadruple diversity. Separate the diversity antennas by 400 wavelengths. Select waveguide or coaxial cable transmission line using best judgment. What other losses will be encountered? Calculate values of RSL.
14 What is the FM improvement threshold if the IF bandwidth is 4260 kHz (60 channels of FDM telephony)?
15 Scale the system in question 5 allowing 3 pWp/km. (How much bigger or smaller than baseline?) Allow NPR = 55 dB.
16 For a digital modulation scheme, an Eb/N0 of 13 dB is required 99.9% of the time to achieve an error rate of 10 5. Rescale the system from baseline (question 5).
17 What sort of dispersion will be found on the sample path in question 16? Give the answer in nanoseconds.
18 If the scatter angle on a certain path can be reduced by 1.5°, will the transmission loss be increased or decreased and by approximately how much?
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