The present invention concerns methods and systems for gathering data concerning usage of media data provided from a predetermined receiver to a user. First data concerning usage of the media data is gathered by means of a portable monitor carried on the person of the user. Second data concerning usage...http://www.google.com.tw/patents/US7483975?utm_source=gb-gplus-share專利 US7483975 - Systems and methods for gathering data concerning usage of media data
