| 332 / | HD | MODULATORS | 
| 117 | DF | FREQUENCY MODULATOR {6} | 
| 123 | DF | .~ Including stabilization or alternatively distortion, noise or other interference prevention, reduction, or compensation {3} | 
| 126 | DF | .~.~ Automatic frequency stabilization or control {1} | 
| 127 | DF | .~.~.~ Phase or frequency locked loop {1} | 
| 128 |  | .~.~.~.~ Modulating signal applied to plural elements of the loop |