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Method and circuit arrangement for determining the presence or not of at least one frequency of a known value in an input signal composed of multiple frequencies
Method and circuit arrangement for determining the presence or not of at least one frequency of a known value in an input signal composed of multiple frequencies
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机译:用于确定在由多个频率组成的输入信号中是否存在已知值的至少一个频率的方法和电路装置
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摘要
Method and circuit arrangement for determining the presence or not of at least one frequency of a known value in an input signal composed of multiple frequencies, wherein four switching signals with frequencies dependent on the frequency to be determined and a phase difference of 90 degrees are generated by means of a frequency generator (61) controlled by a reference frequency and in each case one switching signal is mixed with the input signal in, in each case, one mixer (55, 56, 57, 58), the mixed products of two mixers (55, 56; 57, 58) are, in each case, additively combined and are filtered through, in each case, one filter (27, 28) for filtering out alternating components, and a direct-voltage component contained in the respective mixed product when the known frequency is present is evaluated with respect to the amplitude. …IMAGE…
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