Nielsen's Feb 20, 2003 press release announced a seven year agreement with NBC to provide audience measurement services. The release also referred to a "digital encoding sytem" as follows:
"The agreement also builds on a strong engineering foundation between the two companies. NBC has agreed to implement Nielsen’s digital encoding system to be used in Nielsen’s new metering system for producing television ratings. The new Active/Passive metering system will be introduced in 2004. In sample homes, the A/P Meter will identify programs, stations and networks from electronic codes embedded in programs at the distribution source. NBC and Nielsen engineers will work closely together as new digital distribution systems come to the market."