CS601 Midterm Solved Subjective with References Set 2 by Moaaz

CS601-Data Communication · Latest Solved subjective from Midterm Papers · May 08,2011

Lectures 1-22 Moaaz Siddiq

Latest subjectives

Spring 2010

Q21. How many types of Bipolar encoding scheme exist? (2 marks)

Answer: (PAGE NO.76) Bipolar uses three voltage levels. There are three types of bipolar encoding:

1. AMI (Alternate Mark Inversion)
2. B8ZS
3. HDB3

Q22. Give methods of Analog to Analog conversion. (2 marks)

Answer: (PAGE 95) Analog Conversion: Representation of analog information by an analog signal is Analog –toanalog conversion.

Q23. What is frequency spectrum? (3 marks)

Answer: (PAGE 66) Frequency spectrum is the collection of all the components frequencies it contains.

Q24. How bandwidth of a Modem is measured? (3 marks)

Answer: (PAGE 112)

Bandwidth of a modem is not measured in bytes, it is measured in bits. Modem Speed –ASK (full-duplex) Effective bandwidth of a telephone line is 2400 Hz, the maximum baud rate is also 2400.

Q25. What do you understand by the term DCE? Explain DCE. [5] (5 marks)

Answer: (PAGE 101) Any device that transmits or receives signal through network is DCE. It is any functional unit that transmits or receives data in the form of an analog or digital signal through a network. At the physical layer DCE takes data generated by DTE, converts it to the signal.

Q26. Describe different types of NRZ encoding scheme? (5 marks)

Answer: In NRZ encoding the level of signal is either positive or negative. NRZ is classified into 2 types: NRZ-L NRZ-I

NRZ-L: Level of the signal depends on the type of bit it represents. Positive voltage usually means the bit is a 1 and a negative voltage usually means the bit is a 0.

NRZ-I: The inversion of the level represents a 1 bit. A bit 0 is represented by no change.

NRZ-I is superior to NRZ-L.(PAGE 73)

Spring 2010

Q21. Define Sampling Rate. (2 marks)

Answer: (page82) The accuracy of any digital reproduction of an analog signal depends upon the o. of samples taken

Q22. Write down the types of digital to analog modulation. (2 marks)

Answer: (PAGE 85)

Types of digital to analog modulation ASK FSK PSK QAM

Q23. What is periodic signal? (3 marks)

Answer: (page58)

A signal is called Periodic if it completes a pattern within a measurable time frame called a Period and then repeats that pattern over identical subsequent Periods

Q24. How bandwidth of a Modem is measured? (3 marks)

Answer: (page111)

Bandwidth of a modem is not measured in bytes, it is measured in bits. Modem Speed –ASK (full-duplex) Effective bandwidth of a telephone line is 2400 Hz, the maximum buad rate is also 2400.