| 455 / | HD | TELECOMMUNICATIONS | 
| 
 | 
| 130 | DF | RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER {24} | 
| 230 | DF | .~ Local control of receiver operation {7} | 
| 232.1 | DF | .~.~ Gain control {2} | 
| 234.1 |  | .~.~.~ Automatic {15} | 
| 234.2 | DF | .~.~.~.~> Processor controlled | 
| 235.1 | DF | .~.~.~.~> Forward acting | 
| 236.1 | DF | .~.~.~.~> Variable conversion efficiency (variable oscillator amplitude, etc.) | 
| 237.1 | DF | .~.~.~.~> Responsive to locally injected pilot | 
| 238.1 | DF | .~.~.~.~> Responsive to vehicle speed | 
| 239.1 | DF | .~.~.~.~> Nonlinear automatic gain control {4} | 
| 245.1 | DF | .~.~.~.~> Automatic gain control signal derived from information signal {1} | 
| 246.1 | DF | .~.~.~.~> Responsive to plural inputs {1} | 
| 248.1 | DF | .~.~.~.~> Constant or controlled input impedance | 
| 249.1 | DF | .~.~.~.~> Variable attenuator type | 
| 250.1 | DF | .~.~.~.~> Automatic gain control to improve strong signal handling | 
| 251.1 | DF | .~.~.~.~> Plural stages with different levels or bias to each stage (e.g., partial automatic gain control) | 
| 252.1 | DF | .~.~.~.~> Semiconductor | 
| 253.1 | DF | .~.~.~.~> Plural stages controlled with plates, screen grids, or cathodes connected in parallel | 
| 253.2 | DF | .~.~.~.~> Plural amplifier stages |