Radio Receiver

A Radio Receiver, or colloquially just Radio, is a device used for the detection of radio signals captured by an antenna, and the extraction of information conveyed by them into a usable form, most typically an audio signal.

Types

Radio receivers can be classified based on how they process the radio frequency signal as well as the type of demodulator used. A receiver may be built with multiple demodulators for various signal types.

Tuned Radio Frequency (TRF) Receivers

These receivers have one or multiple band pass filter stages, all tuned to the receiving frequency, before feeding into the demodulator (often called detector) stage.

Multi-stage receivers (and optionally single stage ones) have amplifying stages built between each filter to increase sensitivity and prevent the output signal from becoming too small to be usable.

The following is a list of various TRF receiver types:

• Crystal radio: A passive, single stage receiver using a primitive diode (usually made from a natural semiconductor crystal) as an AM demodulator.