GROL Modulation and Signal Types 2

Question 1

An AM carrier has a peak amplitude of 100V and is modulated at 80%. What is the peak amplitude of each individual sideband?

Accepted Answer

40V

Answer

Each sideband amplitude equals (m/2) × carrier amplitude = (0.8/2) × 100 = 40V.

Question 2

An AM transmitter produces 1000W of carrier power. What is the total output power at 100% modulation?

Accepted Answer

1500W

Answer

Total AM power = Pc(1 + m²/2) = 1000(1 + 0.5) = 1500W at 100% modulation.

Question 3

What is the RF bandwidth of an AM signal with an audio frequency range of 300Hz to 5kHz?

Accepted Answer

10kHz

Answer

AM bandwidth = 2 × highest audio frequency = 2 × 5000Hz = 10kHz.

Question 4

What occurs when an AM signal is overmodulated (modulation index exceeds 1.0)?

Accepted Answer

The carrier is cut off during negative peaks, causing distortion and adjacent-channel splatter

Answer

Overmodulation clips the carrier on negative audio peaks, producing flat-topping that generates harmonics and causes splatter interference on adjacent channels.

Question 5

An AM transmitter operates on 1600kHz and is modulated by a 4kHz audio tone. Where are the two sidebands located?

Accepted Answer

1596kHz and 1604kHz

Answer

The upper sideband is at 1600 + 4 = 1604kHz and the lower sideband is at 1600 − 4 = 1596kHz.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Modulation and Signal Types 2