Chapter Questions
Name five causes of transmission errors. Discuss the effect of each upon a signal.
Explain how atmospheric disturbances can affect transmission.
Describe and discuss a transmission impairment unique to WANs and one unique to LANs.
Compare the typical bit error rates on WAN analog and digital transmission lines to the error rates on a local area network. Why would you expect the LAN bit error rate to be lower?
What is meant by bit error rate testing? How is it performed?
Explain how a full-duplex four-wire circuit could be used for communications even if one wire pair had a very high bit error rate.
Assume that the average bit error rate on a circuit is $10^{-4}$ and data are to be transmitted in blocks of 1024 eight-bit characters. What would you expect to happen to the throughput of data being transmitted? Why
Assume that your transmission line operates at 2400 bps . What BERT test times should be used to determine the bit error rate in terms of bit errors per 100 000 bits?
Under what conditions does a block error rate provide a more realistic performance indicator than obtainable by an examination of a circuit's BER?
What is an errored second?
What is a severely errored second?
What is a failed second?
What is vertical redundancy checking? Discuss five types of vertical redundancy checking.
What would the parity bit setting be for the character whose bit composition is 1010100 if odd parity checking is employed? What would it be if even parity checking is employed?
What is the purpose of the XMODEM protocol checksum? How is that checksum formed?