IT 420 Midterm Exam Key 08S

IT 420 Midterm Exam Key 08S - IT 420 Midterm Exam Key...

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IT 420 Midterm Exam Key Spring 08 Name: Answer the following questions in your exam booklet. Please be as neat and legible as possible. Work must be shown for all problems in order to receive credit . Several questions have multiple parts; make sure that you answer each question completely. Questions 9 and 10 are a continuation of question 8. If you are unable to solve question 8, use your best guess as the data for questions 9 and 10. You will be graded on the answer you use. Definitions: 1 byte = 8 bits 1 kilobyte = 2 10 = 1024 bytes 1 megabyte = 2 20 = 1048576 bytes 10 3 = kilo 10 6 = mega 10 9 = giga 10 -3 = milli 10 -6 = micro 10 -9 = nano bps = bits/second Hz = cycles/second Short Answer 1. When sending a message over a long distance, it is common practice to modulate the data upon a higher frequency carrier. Why is this necessary? The main issue with sending a digital signal over a long distance is signal loss. Basically, attenuation reduces the level of the signal so that it is no longer recognizable. Continuous oscillating signals propagate further than digital signals, so modulating the intelligence onto a carrier allows it to be carried futher. 2. Amplitude Modulation (AM) is very susceptible to interference from weather events like lightning, while Frequency Module (FM) is not. Explain why. AM modulation impresses the data onto the carrier by varying the amplitude (or height) of the carrier. When interference is picked up, it acts in the same manner and
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This note was uploaded on 12/09/2009 for the course CS 431,430,48 taught by Professor Scher,statica during the Spring '09 term at NJIT.

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IT 420 Midterm Exam Key 08S - IT 420 Midterm Exam Key...

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