Chapter 3

___________ is not a type of digital signaling technique.

Data rate signaling

______________ refers to the time it takes for a signal to travel from sender to recipient (highly exaggerated with satellite transmission).

Propagation delay

With which type of digital signaling does the signal always return to zero volts after each bit?

Return-to-zero signaling

Inverse multiplexing means:

combining several low speed circuits to enable them to be transmitted across one high speed circuit

___________ refers to the spreading of the signal that different parts of the signal arrive at different times at the destination.

dispersion

Which of the following media has the lowest error rates and the highest transmission speeds?

fiber optic cable

The two basic types of media are:

guided and wireless (radiated)

The ability to transmit in both directions, but only in one direction at a time is an example of _______________ transmission.

half-duplex

To get more "bandwidth" in a digital transmission, you must:

increase the range of frequencies available for a transmission

Which of the following media is the least secure?

infrared

____________ transmission is prone to interference from smoke, heavy rain and fog and requires line-of-sight.

infrared

Time (non-statistical) division multiplexing differs from frequency division multiplexing because it:

splits the communication circuit vertically (with time slots) instead of horizontally

The type of media usually installed on homes and businesses by the telephone company is called ____________.

twisted pair

The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is a:

wavelength division multiplexer

A coding scheme that uses 10 bits to represent each character is capable of representing _________ different characters.

1024

When sending four bits at a time using frequency modulation, the number of different frequency levels that would be needed would be _______.

16

The typical range of human hearing is:

20 to 14,000 Hz

How many bits are required to sample an incoming signal 4000 times per second using 64 different amplitude levels?

6

When converting analog voice data to digital signals, Pulse Code Modulation typically samples the incoming voice signal _______ times per second.

8,000

If the highest frequency of a circuit is 10KHZ and the lowest frequency is 900 Hz, the bandwidth available for this circuit is:

9100 Hz

With respect to converting digital data into analog signals, AM stands for:

Amplitude Modulation

____________ refers to the transmission characteristics of the circuit.

logical circuit

Which of the following would be considered a type of wireless media?

microwave

__________ is a line-of-sight type of wireless media.

microwave

____________ refers to changing the shape of the sound wave in different ways to represent a 1 or a 0.

modulation

The acronym, Modem, stands for _________________.

modulator/demodulator

________________ separate channels to reduce interference between channels in frequency division multiplexing.

Guardbands

Which of the following is not a key advantage of digital transmission?

It permits only low transmission rates.

The earliest type of fiber optic systems were:

Multimode

Which of the following statements is correct?

Serial transmission is slower than parallel transmission.

Digital Subscriber Line:

all of the above

Microwave transmission:

all of the above

The height of a sound wave is called its:

amplitude

Another term for the weakening of a signal over distance is:

attenuation

The _____________ of a circuit determines a circuit's capacity.

bandwidth

Transmission speeds:

differ widely among media

Which of the following media can best withstand harsh environmental conditions?

fiber optic cable

Frequency division multiplexing:

operates by dividing the signal into different frequencies

The direction in which the sound wave begins is known as:

phase

Which of the following is a characteristic of sound waves that can be modulated to convert digital data into analog signals?

phase

In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which the wave begins?

phase modulation

Data is physically transmitted from one computer or terminal to another in the ________ layer.

physical

____________ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per symbol.

quadrature amplitude modulation

When all bits of a character are transferred one after another, the bits are transferred in ___________ mode.

serial

_____________ is not a form of modulation used to transform digital data into analog signals.

synchronous time division