发明名称 |
UN APARATO PARA LA DETECCION DE UNA SENAL DE TONO CON UNA FRECUENCIA DETERMINADA. |
摘要 |
<p>An apparatus for detection of a tone signal having a predetermined frequency among other tone signals, includes a combined band reject-band pass filter, amplitude limiting means and a product modulator. The signals appearing across the two outputs of the filter have different phases if an input signal has a frequency equal to the tone signal frequency. The value of the phase difference is converted to a DC-component by the limiting means and the modulator, and the magnitude of the DC-component forms an indication of the desired tone signal.</p> |
申请公布号 |
ES452073(A1) |
申请公布日期 |
1977.10.01 |
申请号 |
ES19730004520 |
申请日期 |
1976.10.02 |
申请人 |
TELEFONAKTIEBOLAGET, L. M. ERICSSON |
发明人 |
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分类号 |
G01R23/02;H04Q1/46;(IPC1-7):04Q/ |
主分类号 |
G01R23/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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