| 摘要 |
PATENT 390100-2133 A CIRCUIT FOR DETECTING A VIDEO MODE The detection of whether an input FM signal, such as a reproduced signal, which includes particular frequency components representing predetermined information, was recorded in a first or second mode, with the modes having different frequency bands. A first output signal is produced when a particular frequency component in one of the frequency bands is detected and a second output signal is produced when a different frequency component, approximately equal to the difference between twice a predetermined frequency included in the other of the frequency bands and the particular frequency in the one frequency band, is detected. A mode identifying signal indicative of the frequency band occupied by the FM signal is produced in response to the first and second output signals. |
