发明名称 |
Data communication over telephone voice channel using DTMF interface |
摘要 |
A multifrequency tone generator sends data over a telephone voice channel. An alphanumeric character generator sequentially generates alphanumeric characters. Preferably, the character generator may be a keypad or keyboard. A plurality of tone generators have a summed output for transmitting a tone signal selectably including a combination of standard DTMF frequency tones, but not restricted to always having both frequency tones usually paired together by standard DTMF tones. A translation circuit is responsive to an alphanumeric character from the character generator to activate the plurality of tone generators to produce a predetermined combination of the DTMF frequency tones corresponding to the alphanumeric character wherein each bit of the binary ASCII code is represented by a respective one of the individual DTMF frequencies.
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申请公布号 |
US6751303(B1) |
申请公布日期 |
2004.06.15 |
申请号 |
US20020185440 |
申请日期 |
2002.06.28 |
申请人 |
SPRINT COMMUNICATIONS COMPANY L.P. |
发明人 |
COOK FRED S. |
分类号 |
H04M11/06;(IPC1-7):H04M11/00 |
主分类号 |
H04M11/06 |
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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