connectivity. As in LOS microwave, EMC can be an issue. The limits of fiber optics are still being explored. All terrestrial buried and aerial cable systems are vulnerable to severing by natural disaster or by man. Coaxial cable is limited by amplitude-frequency response characteristics. In nearly every instance, fiber-optic cable connectivity is preferred. Severing may also be a problem. REVIEW EXERCISES REVIEW EXERCISES 1. For very-high-capacity transmission systems (e.g., >20,000 equivalent voice channel), what transmission medium should be selected? 2. What are the advantages of using the RF bands from 2 GHz to 10 GHz for trunk telephony/data? Name at least two. Discuss the problem of delay in speech telephone circuits traversing a geostationary satellite. Will there be any problem with data and signaling circuits? 4. Give four of the five basic procedure steps in designing an LOS microwave link. 5. Where is earth curvature maximum on an LOS microwave path? 6. In a path profile, what are the three basic increment factors that are added to obstacle height? 7. When a K factor is 4/3, does the radio ray beam bend away or toward the earth? 8. Name at least four parameters that we will derive from a path analysis to design an LOS microwave link. 9. Calculate the free space loss of a radio link operating at 4100 MHz and 21 statue miles long. 10. What is the EIRP in dBW out of an LOS microwave antenna if the transmit power is 2 W, the transmission line losses are 3.5 dB, and the antenna gain is 36 dB? 11. A receiving system operating at room temperature has a 5-dB noise figure, and its bandwidth is 2000 kHz. What is its thermal noise threshold? 12. A receiver operating at room temperature in a digital LOS microwave link displays a noise figure of 2 dB. What is its No? 13. What theoretical bit packing can we achieve with QPSK? With 8-ary PSK? 14. What efficiency can we expect from an LOS microwave parabolic antenna bought off-the-shelf? 15. What is the cause of the most common form of fading encountered on an LOS mic