What is amplitude demodulator?

Answer 1

(I am assuming you want to know what an "AM Demodulator" is, as follows) AM stands for Amplitude Modulation, perhaps the most basic kind of modulation of a radio carrier wave. Information, typically voice or music, is impressed on a radio carrier by simply varying the strength or 'amplitude' of the carrier (which is ordinarily at a much higher frequency than the information signal) versus time. An AM Demodulator, then, is a device which recovers the original signal, that is the voice or music, from the modulated carrier wave after it has been transmitted from the source to the receiver (which typically filters and amplifies the received signal before it is applied to the demodulator). The simplest AM Demodulator is a simple "diode", a 2 terminal semiconductor (or vacuum tube) device which, together with another filter, can convert the AM modulated carrier directly into the original form, discarding the carrier wave in the process. This is known as an "Envelope Detector". Other types of AM Demodulators exist, principally the "Product Detector". See the subtopic "AM Radio" in the Wikipedia entry for "Demodulation" for a little more information (it's not overly technical).