69,000 PPMs are already in use in the US, measuring radio exposure in 44 of the country’s top media markets. During the games, which run for three weeks from 27 July, the devices will also record exposure to NBC’s broadcast and cable content that people encounter while out and about.

PPMs pick up on inaudible codes embedded in the audio content of a broadcast. A low-power radio frequency transmitter installed in a respondent’s home is used by the PPM as an ‘at home’ beacon to enable it to distinguish between in-home and out-of-home viewing.

NBC previously worked with Arbitron on measuring audiences for the 2010 Winter Olympics. For this year’s event, the broadcaster has already announced partnerships with Google and ComScore to track viewing across platforms, including TV, mobiles, PCs and tablet devices.