Abstract: To accurately detect the channel being actually selected by a TV having built therein a digital tuner, a terminal device connected to the TV analyzes the preamble of a digital audio signal from the TV to thereby detect a change of audio data-type, and for each viewing period from the time of the change of audio data-type to the time of the next change of audio data-type, generates viewing block data containing comparison feature data extracted from data-bursts within the viewing period concerned and time data of the viewing period concerned, and transmits the generated viewing block data to a center apparatus. The center apparatus identifies, for each viewing block, the actually selected channel by making a comparison between the comparison feature data contained in the viewing block data received from the terminal device and reference feature data contained reference data of each channel stored in the reference data storage part.

Abstract: A portable recorder which is carried by a sample subject for a radio listener rating survey has a display unit and an input unit mounted on the front of a case and a processor built in the case. The processor comprises a data memory, data entry support means, data recording means, and a data readout means. The data entry support means displays the current date and time, a tuned station candidate and a place-of-listening candidate on the display unit, thereby supporting a user in his entering the listening start date and time, the name of the tuned station, the place of listening and the listening stop date and time via the input unit when he listened to a radio program at home or outdoors. The data recording means electronically records the radio listening status data containing values of respective items entered under the support of the data entry support means and finally determined by the user.

Abstract: A television channel selection monitoring apparatus for identifying the broadcast channel to which a television receiver means is tuned at any given time is disclosed. Instead of relying for the channel identification on the local oscillation frequency at the tuner of such television receiver means, the apparatus of the present invention utilizes the recognition of the channel identification number superimposed on the video signal received through the selected channel so that the image of the superimposed channel number may appear, for a certain duration following the channel selection, at a predetermined area of the image corresponding to the video signal.

Abstract: A monitoring apparatus for the use status of a car radio is disclosed. In addition to the function of identifying a radio station to which the car radio is tuned at any given time, the present apparatus is capable of identifying the individual actually in the driver's seat listening to that radio station, and of measuring the idle time during which the car radio could have been turned ON but actually was not. Also, the present apparatus has a rechargeable battery dedicated thereto, thereby to avoid overloading the vehicle-mounted storage battery used also for engine starter. Moreover, the present apparatus comprises a device for generating an excessive discharge alarm signal when the excessively discharged state of the rechargeable battery is detected. Furthermore, the present apparatus employs the radio station identification based on the detection of local oscillation frequency picked up at the tuner portion, which is in one to one correspondence with a radio station broadcast frequency.