Question

Describe Amplitude Modulation technique with a diagram (use binary data 01001100011. Draw both digital and analog signals. (2 points)

Answer 1

Amplitude modulation technique using binary data can be achieved by amplitude shift keying.

Amplitude shift keying is a type of digital modulation technique in which the amplitude of the carrier signal is varied in accordance with tha applied digital signal input.

It is also known as on-off keying and this modulation technique works as a switch. When there is binary one, then carrier signal is transmitted and when there is binary zero, then no carrier is transmitted.

Block diagram of this modulation technique is shown below along with input and output waveforms :

Diagscam oſ estuuplitude Modulation using binary Beta On- off mit) Binary Encoder Product Modulator ASK Signal (+) Carnica Signal clt) Waveform of Analog & Digital Signal mit) 1 0 0 1 1 o o 1 1 >t clt) Ac arman *t -Ac s(t)=mcell.cc Ac in t -Ac HTU

In the diagram, first the binary data is applied to on-off encoder. This on-off encoder converts binary data into a digital signal pulse which is a message signal m(t). Then this message signal is applied to product modulator along with carrier signal c(t). In this block, product operation takes place after which amplitude shift keying(ASK) signal s(t) is generated.

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Waveform explanation:

As per question, given binary data is 01001100011. This data is shown by waveform of message signal m(t). A sinusoidal carrier signal waveform is represented by c(t) and ASK signal by s(t). Ac is the maximum amplitude of carrier signal.

Carrier signal is transmitted when there is 1 in the m(t) and no transmission when there is 0. This also explains the switch like functioning of ASK modulation.