What is the function of the modulator in a radio transmitter?

What is the function of the modulator in a radio transmitter?

• A. Adds useful information to the carrier wave
• B. Amplifies the carrier wave
• C. Filters out noise from the carrier
• D. Converts the signal to digital form

Answer: (A)

The main idea here is that modulation is about encoding the information you want to send onto a carrier signal by varying one of its properties. The modulator’s job is to imprint the input signal onto the high-frequency carrier so the information can travel through space. Without modulation, a carrier would carry no message. That’s why adding useful information to the carrier wave is the best description of the modulator’s function. Different modulation schemes vary the carrier’s amplitude, frequency, or phase in step with the information signal, but all share the purpose of transferring the message onto the carrier. Amplifying the carrier simply increases its power, which helps the signal reach farther but doesn’t encode information. Filtering out noise is done to improve signal quality, not to create or transfer the message. Converting the signal to digital form describes analog-to-digital conversion, not the act of modulating the carrier (even though some modulation schemes use digital data, the conversion itself isn’t the modulator’s primary role).

The main idea here is that modulation is about encoding the information you want to send onto a carrier signal by varying one of its properties. The modulator’s job is to imprint the input signal onto the high-frequency carrier so the information can travel through space. Without modulation, a carrier would carry no message.

That’s why adding useful information to the carrier wave is the best description of the modulator’s function. Different modulation schemes vary the carrier’s amplitude, frequency, or phase in step with the information signal, but all share the purpose of transferring the message onto the carrier.

Amplifying the carrier simply increases its power, which helps the signal reach farther but doesn’t encode information. Filtering out noise is done to improve signal quality, not to create or transfer the message. Converting the signal to digital form describes analog-to-digital conversion, not the act of modulating the carrier (even though some modulation schemes use digital data, the conversion itself isn’t the modulator’s primary role).