| 摘要 |
An adapter is provided for use with a television receiver to detect and decode stereophonic audio signals, SAP signals or auxiliary signals that may be transmitted with the composite television signals. The adapter includes an IF input that is physically separate from the television receiver for receiving IF audio signals that normally are derived from the transmitted composite telephone signals. Detecting circuitry is coupled to the IF input by means of a tuned circuit that is tuned to the IF carrier frequency of the received IF audio signals for detecting the stereo, SAP or auxiliary signals transmitted with the composite television signals. The detected signals are used to drive utilization means, such as loudspeakers. Preferably, switches are provided to select the stereo or SAP or auxiliary signals for detection.
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