Digital Modulation & Multiplexing

The process of converting between bits and signals that represent them is called __________________

digital modulation

Talk about Baseband transmission

Baseband transmission is the signal that occupies frequencies from zero up to a maximum that depends on the signaling rate

Baseband transmission is common for ____

wires

Passband transmission regulates the amplitude, _________ or ________ of a carrier signal to convey bits

phase, frequency

In a passband transmission, the signal occupies a band of frequencies around the frequency of __________

the carrier signal

Paseband transmission is common for __________

wireless and optical transmissions

Explain Manchester encoding

• Mix the clock signal with the data signal by XORing them together so that no extra line is needed.

• The clock makes a clock transition in every bit time, so it runs at twice the bit rate

The downside of Machester encoding is that it requires twice as much bandwidth as ______ due to ______

NRZ, the clock

The USB (Universal Serial Bus) standard for connecting computer peripherals uses ____. With it, long runs of 1s do not cause a problem.

NRZI

A scrambler works by _______

XORing the data with a pseudorandom sequence before it is transmitted

Scrambling is attractive because _________________

it adds no bandwidth or time overhead

What are balanced signals?

Balanced signals are signals that have as much positive voltage as negative voltage even over short periods of time

Balanced signals have no DC electrical component, true or false?

True

The lack of DC component in balanced singals is an advantage because _____________

some channels, such as coaxial cable or lines with transformers, strongly attenuate a DC component due to their physical properties