发明名称 |
TONE SIGNAL DETECTING CIRCUIT |
摘要 |
A tone signal detecting circuit for use in a paging receiver or the like employs an N-path filter in place of an active filter to facilitate circuit integration. The circuit includes a clock signal generating circuit responsive to a first control signal for selecting and reading out one of plural clock signals of a frequency equal to N (N being an integer equal to or greater than 2) times the frequency of the plural tone signals. The N-path filter has a prescribed rise and fall time and selects and responds to a tone signal in accordance with a clock signal from the clock signal generating circuit. A low-pass filter having prescribed frequency characteristics removes harmonic signals of the tone signals contained in the output of the N-path filter. A tone designating circuit responsive to a second control signal is connected to the low-pass filter and changes its frequency characteristics. A detector is connected to the output of the low-pass filter, and control circuits are responsive to the output of the detector to generate the first and second control signals. |
申请公布号 |
AU3089777(A) |
申请公布日期 |
1979.05.31 |
申请号 |
AU19770030897 |
申请日期 |
1977.11.23 |
申请人 |
NIPPON ELECTRIC CO., LTD. |
发明人 |
TOSHIHIRO MORI;TAKASHI ODA;KOICHI NAGATA |
分类号 |
H04W88/02 |
主分类号 |
H04W88/02 |
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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