发明名称 |
Multifrequency signal receiver |
摘要 |
{PG,1 Detection of valid two-out of-N multifrequency signals is realized by employing a microprocessor in conjunction with a controllably adjustable or settable reference threshold level and a plurality of threshold detectors. Under control of the processor, a reference threshold level supplied to the detectors is set to a first prescribed level. Upon detection of a tone which exceeds the first threshold level the processor controllably sets the reference threshold level to a second prescribed level. Detection of two, and only two, tones which are present for at least a minimum prescribed interval are then considered valid.
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申请公布号 |
US4091243(A) |
申请公布日期 |
1978.05.23 |
申请号 |
US19770819112 |
申请日期 |
1977.07.26 |
申请人 |
BELL TELEPHONE LABORATORIES, INCORPORATED |
发明人 |
MIZRAHI, ALBERT;MOYER, NEAL JOHN;PEZZUTTI, DAVID AUGUST |
分类号 |
H04Q1/45;H04L27/26;H04Q1/453;(IPC1-7):H04M1/50 |
主分类号 |
H04Q1/45 |
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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