Member • Nov 18, 2008

## Modulation Problem Solutions

**2**Assume that the binary bit stream {1000110110} is to be modulated using BPSK with a data rate of 1 Mbps.

a.What is the first-zero crossing BW of the RF spectrum if simple rectangular pulses are used?

b.What is the absolute BW of the RF spectrum if raised cosine roll-off pulses are used with α = 1/3?

c.Does the absolute BW in part (b) capture all the energy of the signal?

d.If the receiver experiences 1 μs timing jitter, will the adjacent symbols cause ISI when raised cosine roll-off pulses are used?

**3**An 18,000-feet twisted-pair telephone line has a usable BW of 750 KHz. Data is modulated over this line using QPSK with simple rectangular pulses.

e.What is the maximum bit rate that can be supported over this line such that the first-zero crossing BW consumes the entire usable BW?

f.What will happen if the length of this telephone line is increased to 20,000 feet? (

g.What will happen if the 18,000-feet twisted-pair line is replaced with a coaxial cable of the same length?