The Collaborative International Dictionary of English v.0.48:

demodulator \demodulator\ n. (Electronics)
   An electronic device which extracts the modulation from a
   radio carrier wave, and outputs the original
   information-bearing signal.

   Syn: detector.
        [WordNet 1.5 +PJC]
        [1913 Webster]

WordNet (r) 3.0 (2006):

demodulator
    n 1: rectifier that extracts modulation from a radio carrier
         wave [syn: detector, demodulator]