The advertiser’s dream of sending a particular commercial to a specific consumer is one step closer to reality as Cablevision Systems plans to announce the largest project yet using targeted advertising on television.

Beginning with 500,000 homes in Brooklyn, the Bronx and some New Jersey areas, Cablevision will use its targeting technology to route ads to specific households based on data about income, ethnicity, gender or whether the homeowner has children or pets.

The technology requires no hardware or installation in a subscriber’s home, so viewers may not realize they are seeing ads different from a neighbor’s. But during the same show, a 50-something male may see an ad for, say, high-end speakers from Best Buy, while his neighbors with children may see one for a Best Buy video game.

“We have, as an industry, been talking about this since the beginning of time,” said Matt Seiler, the global chief executive of the media firm Universal McCann, a part of the Interpublic Group. “Now we’ve got it in 500,000 households. This is real.”