| 摘要 |
<p>Many types of electronic equipment emit radio frequency signals. There are environments where the transmission of radio signals may be hazardous, unwelcome or should be restricted in a particular way. These environments include schools, hospitals, theatres, cinemas, conference centres and offices. The presence of such electronic equipment (1, 5) is detected and a controlling device (4, 5, 6, 16, 21) instructs the equipment to suppress radio transmission.</p> |
