| 摘要 |
The standard broadcasting type is automatically identified and the broadcasting signal is tuned according to standard broadcasting type. The decoder system includes a first synchronous signal detector for detecting negative synchronous signal, a second synchronous signal for detecting positive synchronous signal, a microcomputer for identifying standard broadcasting type using the detected synchronous signals, an intermediate frequency audio signal filter for passing AM or FM intermediate frequency signal according to control signal transmitted from a microcomputer, a signal converter for adding output signal of the intermediate frequency audio signal filter to carrier signal of 6.0 MHz, and a signal detector for detecting 4.5 MHz carrier signal in output signal of the signal converter.
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