| 摘要 |
An amplitude modulation detector use peak detection. A CAS (Customer premise equipment Alert Signal) detection apparatus and a caller information detection apparatus use the peak detection and methods for CAS and the caller information detection. The CAS detection apparatus includes a mixing unit, an amplitude modulation detection unit, and a frequency discriminating unit. The mixing unit mixes two or more frequency components of the input signal to generate an amplitude modulated signal including a carrier and an envelope. The amplitude modulation detection unit measures the envelope. Also, the frequency discriminating unit detects whether the frequency of the envelope is in a predetermined range to discriminate whether the CAS is present. Thus, the existence of the CAS can be detected through a single path by mixing a dual tone CAS signal, and can be accurately detected by discriminating the frequency the envelope. Also, the amplitude detection unit capable of detecting the amplitude modulation signal of the CAS can be digitally implemented, so that the CAS detection apparatus can be implemented in a single chip without an external part, and the amplitude modulation detection unit can be applied to all the systems utilizing the amplitude modulation as well as the CAS detection apparatus.
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