Which component recovers intelligence in a receiver?

• A. Filter
• B. Transformer
• C. Amplifier
• D. Detector

Answer: (D)

Recovering intelligence in a receiver happens at the demodulation stage. After the signal is filtered, converted to an intermediate frequency, and amplified, the detector demodulates the carrier to retrieve the original modulating signal—the information you want. In AM, for example, the envelope detector rectifies the carrier and, with a low-pass filter, recovers the baseband audio that carries the message. The other components don’t reconstruct the information content: a filter only selects the desired channel, a transformer handles impedance matching, and an amplifier increases signal strength. The detector is the stage that actually returns the intelligible signal.