16 - Communication definitions

Question 1

Amplitude modulation

Answer 1

Amplitude of the carrier wave is made to vary in synchrony with the displacement of the information signal

Question 2

Frequency modulation

Answer 2

Frequency of carrier wave made to vary in synchrony with the displacement of information signal

Question 3

Noise

Answer 3

Random, unwanted signal that adds to and distorts an information signal

Question 4

Attenuation

Answer 4

Progressive power loss in the signal as it travels along the transmission path.

Question 5

Analogue signal

Answer 5

Signal has same variation(with time) as the data and is continuously variable.

Question 6

Digital signal

Answer 6

Consists of a series of highs and lows and has no intermediate values.

Question 7

Sampling

Answer 7

Taking value of continuous signal at regular intervals

Question 8

Most significant bit

Answer 8

Bit on the left hand side of a binary number with the highest value

Question 9

Cross linking/ cross talk

Answer 9

Signal in one wire pair is picked up by a neighboring wire pair.

Question 10

Surface waves

Answer 10

Travel close to the earths surface and diffract around due to long wavelengths

Question 11

Sky waves

Answer 11

Travel in the atmosphere in straight lines, reflecting back and forth between the ionosphere and the earths surface hence can go a long distance.

Question 12

Space waves

Answer 12

Have a higher frequency so pass through the ionosphere and transmit in the line of sight.