455 / | HD | TELECOMMUNICATIONS |
130 | DF | RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER {24} |
269 | DF | .~ With wave collector (e.g., antenna) {4} |
272 | DF | .~.~ Plural separate collectors {5} |
277.1 | DF | .~.~.~ Selectively or alternately connected to receiver {1} |
277.2 | .~.~.~.~ By signal quality (e.g., noise) |