Abstract: The present invention realizes a highly secure service system which can readily confirm or prove that served information has been actually received by a served party. Authentication information storage means 101 stores authentication information tied to the information to be served and the authentication information is transmitted to the served party by authentication information transmitting means 102. Upon receipt of the authentication information from the served party, service determining means 103 matches the authentication information with the authentication information stored in authentication information storage means 101 to determine successful service of the information to be served. Detailed information presenting means 104 presents the information to be served on a web page accessed by the served party if the authentication information matches.

Abstract: A method and apparatus for conducting a television audience survey in which a channel switch position detector and a television receiver on/off detector is attached to each television receiver in a sampled household and the information obtained from the channel switch position detectors is transmitted as a pulse train signal via a transmission media to a survey center. At the survey center, the pulse train signal is demodulated to recover the transmitted information which is processed in a computer as statistical data.