Page 256 - Satellite Communications, Fourth Edition

236 Chapter Seven

7.11. Briefly describe the equipment sections making up a transponder
channel.

7.12. Draw to scale the uplink and downlink channeling schemes for a
500-MHz-bandwidth C-band satellite, accommodating the full complement
of 36-MHz-bandwidth transponders. Assume the use of 4-MHz guardbands.

7.13. Explain what is meant by frequency reuse, and describe briefly two
methods by which this can be achieved.

7.14. Explain what is meant by redundant receiver in connection with
communication satellites.

7.15. Describe the function of the input demultiplexer used aboard a
communications satellite.

7.16. Describe briefly the most common type of high-power amplifying device
used aboard a communications satellite.

7.17. What is the chief advantage of the TWTA used aboard satellites compared
to other types of high-power amplifying devices? What are the main
disadvantages of the TWTA?

7.18. Define and explain the term 1-dB compression point. What is the
significance of this point in relation to the operating point of a TWTA?

7.19. Explain why operation near the saturation point of a TWTA is to be
avoided when multiple carriers are being amplified simultaneously.

7.20. State the type of satellite antenna normally used to produce a widebeam
radiation pattern, providing global coverage. How are spot beams produced?

7.21. Describe briefly how beam shaping of a satellite antenna radiation
pattern may be achieved.

7.22. With reference to Figure 7.28, explain what is meant by a four-for-two
redundancy switching arrangement.

References

CCIR. 1984. Fixed Services Handbook, final draft. Geneva.
Chetty, P. R. K. 1991. Satellite Technology and Its Applications. McGraw-Hill, New York.
Hyndman, J. E. 1991. Hughes HS601 Communications Satellite Bus System Design
Trades. Hughes Aircraft Company, El Segundo, CA.
Johnston, E. C., and J. D. Thompson. 1982. “INTELSAT VI Communications Payload.”
IEE Colloquium on the Global INTELSAT VI Satellite System, Digest No. 1982/76.
pp. 4/1–4/4.
Lilly, C. J. 1990. “INTELSAT’s New Generation.” IEE Review, Vol. 36, No. 3, March.
pp. 111–113.