3849729 is referenced by 101 patents and cites 6 patents.

The invention relates to a system and device for recording the tuning and working condition of a radio or television set. A record codes the time of any channel change as well as data about operating time after the change. The coding is characterized by means of a series of binary tones identifying different reception channels and a digital indication of the time the set is in use, the recording only being active when the set is in use.

Title
System for determining the listening and viewing habits of wave signal receiver users
Application Number
05/309,885
Publication Number
3849729
Application Date
December 14, 1972
Publication Date
November 19, 1974
Inventor
Van Baggem Johannes Wilhelmus
Agent
Breiner A W
Assignee
Intomart
IPC
H04h 09/00
H04H 09/00
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