Physical Layer: Line Coding and Signal Transmission
Covers physical layer concepts including line encoding schemes (NRZ, RZ, Manchester, AMI), signal attenuation, amplification, SNR calculations, channel capacity, and digital-to-analog conversion techniques.
Questions
Which of the following is used to overcome the problem of attenuation?
- Amplifier
- Low Pass Filter
- High Pass Filter
- Band Pass Filter
- Router
A signal of power 50 W is mixed with a noise of 2 mW. Calculate the SNR ratio in dB.
- 4.39
- 16.97
- 25,000
- 43.98
- None of the above
Which of the following statement(s) is/are true about NRZ line coding scheme?
i. Average signal rate of NRZ is n/2 Bd.
ii. Long sequence of Zero can cause the problem in NRZ-I only.
iii. Long sequence of One can cause the problem in NRZ-L only.
- Only i
- Only i and iii
- Only i and ii
- Only iii
- All the statements are correct
Which of the following is a bipolar line coding scheme?
- RZ
- NRZ-I and NRZ-L
- Manchester
- Differential Manchester
- AMI (Alternate Mark Inversion)
A signal is travelling through any media. If its voltage is reduced to one fourth of its original voltage, calculate the amplification or attenuation (as per the question) in terms of dB.
- - 12.04 (attenuation)
- - 12.04 (amplification)
- + 12.04 (attenuation)
- + 12.04 (amplification)
- - 6.02 (attenuation)
How many lines of voltage have been used in RZ coding scheme?
- 4
- 3
- 2
- 1
- None of the above
Which of the following statement(s) is/are incorrect?
i. Only NRZ-L has a DC component problem.
ii. Sudden change in polarity is a problem in NRZ-L.
iii. NRZ is bipolar in nature.
- Only i
- Only ii
- Only ii and iii
- Only i and ii
- Only i and iii
A system is using NRZ-I to transfer 12-Mbps data. Calculate the average signal rate (S) and minimum bandwidth(BW).
- S = 6 MBaud, BW = 12 MHz
- S = 12 MBaud, BW = 6 MHz
- S = 12 MBaud, BW = 12 MHz
- S = 6 MBaud, BW = 6 MHz
- None of the above
Which of the following statement(s) is/are correct?
i. Data rate is the number of signals sent in 1 second.
ii. Unit of signal rate is bps (bit per second).
iii. Data rate is sometimes called pulse rate.
- Only ii
- Only i
- Only i and ii
- Only iii
- None of the above
Which of the following statement(s) is/are correct?
i. Digital to digital conversion involves three techniques, i.e. Line coding, Block coding and Scrambling.
ii. Common technique to convert analog signal to digital signal is called pulse code modulation (PCM).
iii. According to Nyquist theorem, to represent the original analog signal, one necessary condition is that the sampling rate must be equal to the highest frequency in the original signal.
- Only i
- Only ii
- Only iii
- Only i and ii
- All the statements are correct
Which of the following statement(s) is/are true about Manchester encoding?
i. It is Bipolar scheme of encoding.
ii. There is always a transition in the middle of bit.
iii. If next bit is 1, there is a transition and if next bit is 0, there is no transition.
iv. It is combined idea of RZ and NRZ-I.
- Ony i and ii
- Ony i, ii and iii
- Ony ii and iv
- Ony ii, iii and iv
- All the statements are correct
Which of the following is/are cause(s) of transmission impairment?
- Attenuation
- Distortion
- Amplification
- Only i and ii
- i, ii and iii
A communication channel has a bandwidth of 2.50 KHz assigned for data communication. If the SNR (sound-to-noise ratio) is 2047, calculate the channel capacity of media.
- 27.5 bps
- 27.5 Kbps
- 25 Kbps
- 11 Kbps
- 275 Kbps
Before transmission, data must be transformed into
- electromagnetic signal
- packets
- power of 2
- modulated data
- none of the above
What is the meaning of AMI in terms of encoding?
- Arithmetic Mark Inversion
- Arithmetic Mask Inversion
- Alternate Mask Inversion
- Alternate Mark Identity
- Alternate Mark Inversion