发明名称 |
Supervisory audio tone detection in a radio channel |
摘要 |
Supervisory audio tones received from a mobile telephone unit are converted from analog to digital form. The tone is then converted to a complex number by bifurcating the tone path and multiplying one path by a sine function and the other path by a cosine function. The complex numbers are accumulated and the frequencies where significant power exists is found using the discrete Fourier transform. If the power at an assigned frequency exceeds a threshold, the corresponding supervisory audio tone is declared to have been detected.
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申请公布号 |
US4698769(A) |
申请公布日期 |
1987.10.06 |
申请号 |
US19850698095 |
申请日期 |
1985.02.04 |
申请人 |
AMERICAN TELEPHONE AND TELEGRAPH COMPANY;BELL TELEPHONE LABORATORIES, INCORPORATED |
发明人 |
MCPHERSON, ROSS;SMOLIK, KENNETH F.;THOMSON, DAVID J. |
分类号 |
H04L27/00;H04B7/26;H04Q1/442;H04Q1/446;H04Q7/20;H04Q7/38;(IPC1-7):G06F7/38 |
主分类号 |
H04L27/00 |
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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