05481294 is referenced by 677 patents and cites 13 patents.

An audience measurement system collects data representative of tuned programs rather than of tuned channels, and includes (i) a household metering apparatus which records ancillary codes or extracts program signatures from the programs if no ancillary codes are found therein, (ii) a reference apparatus which monitors broadcast programs to be monitored, which extracts reference signatures therefrom, which records whatever ancillary codes may be associated with these broadcast programs and, if no ancillary codes are present, which compresses and stores a digital replica representative of the broadcast programs to be monitored, (iii) a data collection apparatus which compares the household and reference data to determine (a) which of the broadcast programs to be monitored were selected for viewing and/or listening, (b) which of the metered households selected the broadcast programs to be monitored for viewing and/or listening, and (c) at which times the broadcast programs to be monitored were selected for viewing and/or listening.

Title
Audience measurement system utilizing ancillary codes and passive signatures
Application Number
8/144289
Publication Number
5481294
Application Date
October 27, 1993
Publication Date
January 2, 1996
Inventor
Daozheng Lu
Dunedin
FL, US
William L Thomas
Clearwater
FL, US
Agent
Marshall O Toole Gerstein Murray & Borun
Assignee
A C Nielsen Company
IL, US
IPC
H04N 7/00
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