1. 
   under-modulation
   the condition in which the peak values of the modulating signal stay for a long period of time well below the maximum value permitted by the transmission system or equipment considered
   Found op http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=702-06-21
   
   
2. 
   under-modulation
   the condition in which the peak values of the modulating signal stay for a long period of time well below the maximum value for which the transmission system or the equipment considered is designed
   Found op http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=713-09-31
   
   

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