{i} detection technique used widely in radio which involves combining the measured wave with a wave of different frequency to produce frequencies equal to the amount of and the difference between the two original signals; interference (in particular whistle)
combine (a radio frequency wave) with a locally generated wave of a different frequency so as to produce a new frequency equal to the sum or the difference between the two of or relating to the the beat produced by heterodyning two oscillations
To mix two radio signals of different frequencies to produce a third signal which is of lower frequency, i e , to produce beating
Having alternating currents of two different frequencies that are combined to generate a current that has sum and difference frequencies, either of which may be used in radio or television receivers by proper tuning or filtering