| 摘要 |
PROBLEM TO BE SOLVED: To provide a tone detector (14) which can detect multicomponent tones in various tone formats. SOLUTION: An input signal is received and the frequency and amplitude components, if there is any, of each sample of an incoming signal are estimated (30, 34). In estimating the components, a current numerical value is used to appropriately filter the input signal and estimate frequency and amplitude component. Using the component estimates, a new digit value is determined, using a table in storage (100) corresponding to the current tone format. The new digit value corresponds to a symbol, whose components are closest in value to the estimated components corresponding to the current digit value. The new digit value is fed back as the current digit value and used in combination with a next sample of an input signal, to determine a new digit value. A decision unit (38) is used to process the digit values to determine when a valid symbol is detected. COPYRIGHT: (C)2004,JPO
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