# Thread: CS601-Data Communication Solution of Assignment No. 02 November Fall 2013

1. ## CS601-Data Communication Solution of Assignment No. 02 November Fall 2013

Assignment No. 02
Semester: Fall 2013
CS601-Data Communication

Total Marks: 20
Due Date: 6/12/2013

Question 1: (10 Marks)

You are required to represent the data stream 1001101001 using the following encoding schemes on different graphs separately.

• NRZ-L
• NRZ-I

Question 2: (5 Marks)

a) A periodic signal has a bandwidth of 700 Hz and its lowest frequency is 200 Hz; find out its highest frequency with all necessary steps.

b) Consider the following sine wave, and calculate its time period and frequency.

Question 3: (5 Marks)

Suppose a message travels from device A to B in OSI model. Headers and trailers are added to the message before it reaches the destination B. Considering the given scenario, you are required to identify:
• The sequence of OSI layers in which headers and trailers are added at device A.
• The sequence of OSI layers in which headers and trailers are removed at device B.

2. What is the major difference between NRZ-L and NRZI?

"Non return-to-zero-level (NRZ-L) is a data encoding scheme in which a negative voltage is used to represent binary one and a positive voltage is used to represent binary zero. As with NRZ-L, NRZI maintains a constant voltage pulse for the duration of a bit time. The data themselves are encoded as the presence or absence of a signal transition at the beginning of the bit time. A transition (low to high or high to low) at the beginning of a bit time denotes a binary 1 for that bit time; no transition indicates a binary 0."

The frequency of a wave is the amount of time the wave goes through a complete cycle in a second. The unit of frequency is Hertz, which literally means "per second". So if the frequency of a wave is 30 Hz, the wave goes through 30 complete cycles in one second.
The simplest way to calculate frequency using time would be to count the amount of complete cycles that the wave goes through in a second. Or, if it would be easier, you could count the amount of cycles in a minute and divide by 60 (or hour and divide by 3600, etc.)

3. Best of Luck...

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