Google, the new kid on the block in TV advertising, has signed up with The Nielsen Co., the venerable TV audience measurement company, in a deal that will increase the data available to participants in the Google TV Ads program.

The agreement, expected to be announced Wednesday, calls for Nielsen to supply demographic data about TV viewers to Google, which in turn will use it to complement the information it already provides to advertisers and agencies in its TV advertising platform.

Google TV Ads, operational since May, provides a platform for buying, selling, and distributing television advertising, along with tracking the effectiveness of campaigns.

As it branches out into TV and other offline advertising markets like radio and print publications, Google maintains that it can apply to these markets the benefits of online advertising, in particular the possibility for targeting and tracking ads in a very granular way.

For example, in its online ad system, Google matches ads to the topic of queries on its search engines and to the topic of third-party Web sites that participate in its ad network. Meanwhile, in Google's most popular ad format, called pay per click, advertisers pay only when users click on their ads.

In Google TV Ads, Google captures and aggregates data from TV set-top boxes, giving advertisers constantly updated information about the distribution of their ads. Advertisers pay by set-top box impressions, according to Google.

Wednesday's announcement is the first of a multi-year agreement in which the two companies will explore other opportunities to collaborate.

Google didn't immediately reply to a request seeking comment on whether Wednesday's agreement also calls for Google to provide set-top box usage data to Nielsen.