发明名称 |
METHOD OF AND APPARATUS FOR MODIFYING A VIDEO SIGNAL TO INHIBIT RECORDING THEREOF |
摘要 |
<p>METHOD OF AND APPARATUS FOR MODIFYING A VIDEO SIGNAL TO INHIBIT RECORDING THEREOF Video signal lines are added to or omitted from the ends of individual fields of a video signal to produce a modified video signal whose field length varies at a slow rate. The modified video signal can be broadcast and received by conventional television equipment, normal television reception and viewing being not noticeably affected by the variable field length. However, recording of the modified video signal is inhibited because the field length is not constant. The modified video signal is produced by directly modifying the scanning of televising equipment, or by storing the lines of the video signal in a store and reading them in a controlled manner therefrom. A decoder, for producing a constant field length video signal from the modified video signal, is also disclosed.</p> |
申请公布号 |
CA1187165(A) |
申请公布日期 |
1985.05.14 |
申请号 |
CA19810387297 |
申请日期 |
1981.10.05 |
申请人 |
NORTHERN TELECOM LIMITED |
发明人 |
BOND, JOHN A;LI, YUAN-LU;CRANE, LESLIE J. |
分类号 |
H04N5/913;H04N7/167;H04N7/171;(IPC1-7):H04N5/38;H04N7/16 |
主分类号 |
H04N5/913 |
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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