5. Amplitude Modulation Concepts – 1 Flashcards
What happens in the modulation process?
The voice, video or digital signal modifies another signal called the carrier
What happens in amplitude modulation?
The information signal varies the amplitude of the carrier sine wave
What does Vm < Vc represent?
It means that the peak value of the modulating signals should be less than the peak value of the carrier
When does distortion occur?
When the amplitude of the modulating signal is greater than the amplitude of the carrier
What is a modulator?
A circuit that is used to produce amplitude modulation
Amplitude modulation principles
The first term is the sine wave carrier and the second term is the product of the sine wave carrier and modulating signals
How is AM voltage produced?
AM voltage is produced by a circuit that can multiply the carrier by the modulating signal and then add the carrier.
What is the modulation index?
A value that describes the relationship between the amplitude of the modulating signal and the amplitude of the carrier signal - m = Vₘ / V꜀
Also knows as the modulating factor/coefficient or the degree of modulation
In radio transmission, how is the signal amplified?
Using a power amplifier
How do you get the percentage of modulation?
Multiplying the index (m) by 100
What values should the index be between?
0 and 1
What happens if the modulating voltage is higher than the carrier voltage?
m will be greater than 1, causing distortion (clipping) - a form of distortion that limits a signal once it exceeds a threshold
