Noise (radio)
（重定向自Radio noise）
In radio reception, noise is the superposition of white noise and other disturbing influences on the signal, caused either by thermal noise and other electronic noise from receiver input circuits or by interference from radiated electromagnetic noise picked up by the receiver's antenna. If no noise were picked up with radio signals, even weak transmissions could be received at virtually any distance by making a radio receiver that was sensitive enough. In practice, this doesn't work, and a point is reached where the only way to extend the range of a transmission is to increase the transmitter power.