Physical Layer Question Pool

1. What is the difference between a repeater and an amplifier?
2. Discuss the disadvantages of repeaters.
3. What is the purpose of the wiring closet?
4. Name at least three things normally found in a wiring closet.
5. Why do we terminate coaxial cable?
6. What form of modulation is most appropriate for optical fiber?
7. Label the three parts of optical fiber.
8. What is the difference between the terms frame and packet?
9. What is the main difference between synchronous and asynchronous signaling? Which is more efficient and why?
10. What is the purpose of bit stuffing?
11. What is framing?
12. Explain the purpose of the preamble in 802.3.
13. How does the bandwidth requirement of a Manchester encoded signal relate to its data rate?
14. Explain the relationship between media bandwidth and data rate. What is one of the major factors why the ideal relationship is not obtained in practice?
15. According to Nyquist, what is the maximum data rate at which a 4-kHz channel can transmit binary signals?
16. What is the limit of changes per second in a signal defined as? a. bandwidth b. data rate c. baud d. frequency
17. List the three major media types in order of increasing bandwidth.
18. What is the difference between Topology and Geography? Give definitions of each and a specific example where network geography is different from the topology.
19. What media is least suited for a bus geography?
20. What media typically uses an RJ-45 connector?
21. What media typically involves an AUI connector?
22. What is the difference between 10BASE5 and 10BASE2?
23. What is the limiting factor in achieving high data rates on fiber? (Why does single mode fiber have the potential to support a higher data rate than multimode fiber?)
24. If a fiber is specified as 400 MHz-km, it means you can have a bandwidth of ________ MHz over a 2 km distance or a bandwidth of __________ MHz over a 0.5 km distance.
25. Discuss ISDN. {Explain the acronym, list at least three 'facts' about it}
26. What is a BRI?
27. Discuss ADSL. {Explain the acronym, list at least three 'facts' about it}
28. What is the difference between FDM and TDM?
29. What is the difference between STDM and TDM?
30. What is the difference between STDM and packet switching?
31. A broadband coax data system generally has a Tree geography. What is the base/root of the tree called?
32. What two signals in an RS-232 interface indicate the connected device is powered on?
33. Collectively, what are ASK, FSK, PSK and QAM?
34. What is a self-synchronizing signal?
35. What is/are the major cause(s) of errors at the physical and link layers?
36. Do signals travel further in shielded or unshield twisted pair and why?
37. Define "Propagation Speed".
38. Match the following terms with their definitions.
    

    i. propagation		a. number of oscillations per second of the electromagnetic field of the signal
    ii. frequency		b. number of bits per second
    iii. bandwidth		c. changes per second in the signal
    iv. data rate		d. how fast the signal travels in that media, especially compared
    v. baud		e. the width/size, in Hz, of the signal--usually defined by where most of the energy is

39. CIS's V.90 modems are up and running.
    What is the data rate of these lines?
    What is the baud rate of these lines?