What is the primary function of a demodulator in radio systems?

• A. To amplify the radio signal
• B. To extract information from the modulated carrier wave
• C. To change the frequency of the signal
• D. To filter out unwanted noise

Answer: (B)

The primary function of a demodulator in radio systems is to extract information from the modulated carrier wave. In radio communications, information such as voice, music, or data is transmitted by modulating a carrier wave, which involves varying parameters like amplitude or frequency according to the information signal. The demodulator processes the incoming modulated signal and retrieves the original information by reversing the modulation process. This is a crucial step in communication systems as it enables the received signal to be understandable or usable by the end device, such as a radio receiver or a data modem.

While amplification, frequency conversion, and noise filtering are important functions in radio systems, they are not the primary role of the demodulator. Amplification enhances the strength of the signal for better reception, frequency conversion can shift the signal’s frequency for easier processing, and filtering removes unwanted noise that can interfere with the clarity of the received signal. Each of these functions plays a complementary role in the overall system, but the specific task of extracting the original information is solely the responsibility of the demodulator.