发明名称 |
Method and apparatus for secure audio channel transmission in a CATV system |
摘要 |
A secure audio channel transmission system method and apparatus in which an FM signal is generated on an FM broadcast frequency, such as 107.5 megahertz, divided in frequency by 2 and distributed via a cable television system to subscribers equipped with frequency doubler circuits that reconstitute the FM signal for reception on a standard FM broadcast receiver. Unauthorized reception is prevented by the use of the non-standard, frequency-divided signal which is not receivable by standard broadcast channel television or FM receivers.
|
申请公布号 |
US4586081(A) |
申请公布日期 |
1986.04.29 |
申请号 |
US19800144362 |
申请日期 |
1980.04.28 |
申请人 |
LINCOLN CENTER FOR THE PERFORMING ARTS, INC. |
发明人 |
ST. ARNAUD, WILLIAM J.;SWITZER, ISRAEL |
分类号 |
H04H20/77;H04H20/79;(IPC1-7):H04N7/167;H04N7/04 |
主分类号 |
H04H20/77 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|