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Method and apparatus for detecting subscriber alerting signal tones and customer premises equipment alerting signal tones to non-echo canceling modems
Method and apparatus for detecting subscriber alerting signal tones and customer premises equipment alerting signal tones to non-echo canceling modems
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机译:用于检测非回音消除调制解调器的订户警报信号音和客户驻地设备警报信号音的方法和装置
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摘要
A non-echo canceling voice band modem capable of detecting subscriber alerting signal (SAS) tones and customer premises equipment alerting signal (CAS) tones is provided. The modem includes a shaping filter, an analog-to-digital converter (ADC), a SAS tone detector, a CAS tone detector and an echo canceler. The shaping filter, which is located in a transmitting path of the modem, filters modem signals to be transmitted from the modem. The ADC, which is located in a receiving path of the modem, converts any incoming analog signal to corresponding digital signals to be used by the modem. The echo canceler, which is coupled to the SAS and CAS tone detectors, cancels any echoes in modem signals before sending said modem signals to the SAS and CAS tone detectors.
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