发明名称 |
AUTOMATIC FREQUENCY CONTROL SYSTEM AND METHOD FOR FREQUENCY-SHIFT-KEY DATA TRANSMISSION SYSTEMS |
摘要 |
The present invention provides a system and method of automatic frequency control (AFC) in a frequency-shift-key (FSK) data transmission system that allows a receiver to be used that has a bandwidth that approaches the requisite minimum bandwidth for a given data transmission rate and produces a substantial signal noise ratio (SNR) in the detected signal by the receiver. The invention includes a transmitter that outputs a SPACE signal and a MARK signal in a preamble that precedes the transmission data. The apparatus also includes a receiver (24) that uses the SPACE and MARK signals to adjust the freguency of the signal output by a voltage-controlled-oscillator (VCO) (42) to tune the receiver and thereby improve the signal-to-noise ratio (SNR) in the signals subsequently detected by the receiver. <IMAGE> |
申请公布号 |
ZA9107409(B) |
申请公布日期 |
1992.05.27 |
申请号 |
ZA19910007409 |
申请日期 |
1991.09.17 |
申请人 |
IN-SITU, INC. |
发明人 |
RICHARD W. WEEKS;EDWARD R. EISENHAUER |
分类号 |
H04L27/16 |
主分类号 |
H04L27/16 |
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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