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Title:
Interrogating system for subscription television receivers
United States Patent 3396232
Inventors:
Hendrickson, Melvin C.
Morris, George V.
Application Number:
US37969064A
Publication Date:
08/06/1968
Filing Date:
07/01/1964
Assignee:
ZENITH RADIO CORP
Primary Class:
Other Classes:
346/37, 348/E7.07, 380/241, 725/2, 725/131
International Classes:
H04N7/173
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US Patent References: