| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect presence of an FM signal by a game machine that uses the FM signal to communicate with other game machines. SOLUTION: This frequency modulation signal detecting circuit is provided with an RSSI circuit 324, that generates a strength signal RSSI whose voltage is increased in response to the intensity of an FM signal, a white noise detection circuit 325 that generates a white noise detection signal WN whose voltage is increased in response to the intensity of the white noise included in a demodulation signal DEM from a detector 317, and a discrimination circuit 326 that compares the intensity signal RSSI with the white noise detection signal WN to generate a detection signal DET. Thus, by installing the frequency modulation signal detecting circuit cannot detect noise signals intruded more or less to the circuit as FM signals by mistake, when no FM signal is in existence. |
