Deck 2: Wireless Data Transmission

Question 1

Explain the difference between amplitude modulation, frequency modulation, and phase modulation.
Amplitude modulation changes the height of a wave. Frequency modulation changes the frequency of a wave, and phase modulation changes the starting point of a wave with reference to the previous cycle of the same wave.

Answer 1

Amplitude modul ation changes the height of a wave Frequency modulation changes the freq uency of a wave, and phase modulation changes the starting point of a wave with reference to the previous cycle of the same wave

Question 2

Eight binary digits grouped together form which of the following?

A) byte
B) bit
C) binary
D) 2x quad

Answer 2

A

Question 3

The distance between one positive peak and the next positive peak of a wave is called: _________.

A) frequency
B) wavelength
C) elasticity
D) intensity

Answer 3

B

Question 4

Letters of the alphabet and symbols are stored using the ASCII code, but not numbers used in calculations.

Question 5

Infrared wireless transmission can be either directed or _________.

A) analog
B) digital
C) diffused
D) detected

Question 6

What is quadrature amplitude modulation (QAM) and how does it work?
QAM is a modulation method that changes both the phase and height of a wave, in order to encode more than one bit per signal change (baud).

Question 7

PSK is an example of _______.

A) ASCII encoding
B) unicoding
C) phase modulation
D) digital modulation

Question 8

Unlike a digital signal, a(n) ________ signal is a continuous signal with no "breaks" in it.

A) magnetic
B) visible
C) light
D) analog

Question 9

Infrared wireless systems require that each device have only one component: either an emitter that transmits a signal or a detector that receives the signal.

Question 10

Infrared wireless systems send data by the intensity of the light wave instead of whether the light signal is on or off.

Question 11

Infrared light, though invisible, has many of the characteristics of visible light.

Question 12

Explain how a radio antenna works when transmitting a signal.
When the electricity moves back and forth in the antenna at the same frequency as the radio waves, it creates both a magnetic field and an electrical field around the antenna. This continuous (analog) combination of magnetism and electrical pressure moves away (propagates) from the antenna the same way that water waves move away from the point of impact when you throw a rock in a pond.

Question 13

Which range of the electromagnetic spectrum is less susceptible to interference from sources of visible light?

A) ultraviolet
B) gamma light
C) infrared
D) yellow light

Question 14

List and describe the three different types of binary signaling techniques.
In return-to-zero, the absence of a voltage, or zero volts, represents a 0 bit and an increase in voltage represents a 1 bit. The signal rises and falls within a bit time period. In non-return-to-zero, the voltage does not change when the next bit is the same as the previous bit. Non-return to zero level, works the same way as non-return- to-zero, but the voltage changes between a positive and negative level, rather than between a positive voltage and zero volts, as in the previous two techniques.

Question 15

Radiotelephony or radio travels in waves known as _________ waves.

A) electromagnetic
B) analog
C) magnetic
D) electrical

Question 16

Changing a signal to encode data onto it is known as __________.

A) baud
B) demodulation
C) modulation
D) continuity

Question 17

Which type of transmission is used when human voice is modulated directly onto a carrier wave?

A) analog
B) digital
C) diffused
D) directed

Question 18

Explain the difference between bps and baud rate.
Baud rate refers to the number of signal changes per second. Because each signal change can represent more than one bit, the number of bits-per-second, or bps, can be higher than the baud rate.

Question 19

Why do computers and data transmission equipment use binary?

A) They are electrical devices, and electricity has only two states.
B) Base 2 is too difficult to use.
C) Base 10 was developed before binary.
D) Binary is the next step beyond quadecimal.

Question 20

The American Standard Code for Information Interchange (ASCII) can represent up to 1024 characters.