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Examination of twisted pair link

A twisted pair telephone line is equipped with an equalizer that ensures the line has a constant attenuation between 300 Hz and 3300 Hz, and linear phase shift with frequency. A carrier at a frequency of 1800 Hz is modulated with QAM so that digital data can be transmitted on the twisted pair. The transmitter and receiver have ideal RRC filters with roll off factor (r) = 0.5.

a. What is the maximum symbol rate that the twisted pair line can carry without ISI?

b. 256-QAM modulation is used on the link. How many bits are conveyed by each symbol?

c. What is the bit rate on the link?

Solution Preview

(a) In order to avoid ISI at baseband transmission the bandwidth criteria must be such that the bandwidth {B(min)} satisfies following condition.

B(min) = R(S)/2 (1) where R(S) is the Symbol rate.

Bandwidth of the transmission ...

Solution Summary

Various features of a twisted pair telephone line are examined including ISI. QAM 256 modulation is exanmined and the bit rate for the link of known parameters determined