UNIT 4 ERROR CONTROL CODING: BLOCK CODES

Error detection at the data link level is achieved by

• Bit stuffing

• cyclic redundancy codes

• Hamming codes

• Equalization

Which error detection method uses one’s complement?

• 
  Simple parity check

• Two dimensional parity check

• CRC

• Checksum

The checksum of 1111 and 1111 is ----------

• 
  1110

• 
  0000

• 1111

• 0111

which is/ are the error detection technique?

• CRC

• VRC

• LRC

• Check sum

• All of these

Bit stuffing refers to

• Inserting a "0" in user data stream to differentiate it with a flag

• Inserting a "0" in flag stream to avoid ambiguity

• Appending a nibble to the flag sequence

• Appending a nibble to the user data stream

According to Shannon Hartley theorem,

• The channel capacity becomes infinite with infinite bandwidth

• The channel capacity does not become infinite with infinite bandwidth

• Has a tradeoff between bandwidth and Signal to noise ratio

• Both b and c are correct

Information rate is defined as

• Information per unit time

• Average number of bits of information per second

• rH

• All of the above

The memory less source refers to

• No previous information

• No message storage

• Emitted message is independent of previous message

• None of the above

If the channel is bandlimited to 6 kHz & signal to noise ratio is 16, what would

be the capacity of channel?

• 15.15 kbps

• 24.74 kbps

• 30.12 kbps

• 52.18 kbps

In a linear code, the minimum Hamming distance between any two code words

is ______minimum weight of any non-zero code word.

• Less than

• Greater than

• Equal to

• None of the above