‘ IS320 Assignment 3

EID:E00967775

Name: Yma Johnson

  1. Your computer screen has a resolution of 800 pixels horizontally and 600 pixels vertically.
  2. How many bytes will a JPEG screen image be if there is no compression? Express the file size in proper notation. Use B for bytes.

1.44 MB

  1. How long will it take to transmit the file over a 30 kbps line?

48 sec

  1. How large would the file be with 20:1 compression (which is common)?

72 kb

  1. How long will it take to transmit the file over a 30 kbps line?

2.4 sec

  1. A signal is 1/16 of its initial powerwhen it arrives at the receiver. What is the power ratio in decibels?

-12 dB

  1. A signal is 1/10000 of its initial value when it reaches the receiver.What is this power ratio in decibels?

40 dB

  1. What problems (or problem) are reduced to acceptable limits by limiting the length of a UTP cord in Ethernet?

Attenuation

  1. Distinguish between electromagnetic interference (EMI), crosstalk interference, and terminal crosstalk interference.

Electromagnetic interference are unwanted interferences from external devices like motors, microwaves. Crosstalk interference and terminal crosstalk interference are types of EMI. Crosstalk interference is caused by energy radiated from UTP wires next to each other, twisting the wires reduces this problem.. Terminal cross-talk interference occurs where the UTP wire is no longer twisted while I entering the connector and is usually a much larger problem than crosstalk interference.

  1. In LAN transmission, what are the typical roles of UTP and optical fiber?

UTP is used for access limes because it’s cheaper, sturdier and access line distances are typically well within 100 meter range of UTP. Optical fiber is used for

  1. Are noise and interference major propagation problems for optical fiber propagation? Explain.

No, because the fiber is encased in cladding that blocks external interference. Any light interference is absorbed into the optic fiber.

  1. If the signal strength from an omnidirectional radio source is 8 milliwatts (mW) at 30 meters, how strong will it be at 120 meters, ignoring absorptive attenuation? Show your work.

S2 = S1 * (r1/r2)

S2= 8 * ¼

S2= 8*1/16

S2 = 1/2

  1. How many possible paths are there between any two computers in
  2. a point-to-point topology?

1

  1. In a hierarchical topology? (Hint: Draw a picture.)

1

  1. In a mesh topology with four switches (without back-tracking)? (Hint: Draw a picture.)

5

  1. What kinds of errors are you likely to encounter if you run a length of UTP cord 200 meters? (Recall that the standard calls for a 100-meter maximum distance.)

Noise errors, attenuation, EMI and signal loss

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