Four of the nation's largest radio networks--Bonneville International, Emmis Communications, Greater Media, and Lincoln Financial Media--announced Thursday they were signing up for ratings results
from Arbitron's new Portable People Meter (PPM), a passive electronic monitoring device that picks up encoded audio signals from a variety of sources including radio. The four firms will begin
receiving PPM results once the device has been deployed in the 50 markets identified by Arbitron for final rollout.
--Erik Sass