Abstract: A data hiding system is described for hiding data within an audio signal. The system can be used for watermarking, data communications, audience surveying etc. The system hides data in an audio signal by adding artificial echoes whose polarity varies with the data to be hidden. In one embodiment, each data value is represented by a positive and a negative echo having different delays. A receiver can then remove the effects of natural echoes and/or periodicities in the audio signal by differencing measurements obtained at the different delays.

Abstract: A captioning system is provided for providing captions for audio and/or video presentations. The captioning system can be used to provide text captions or audio descriptions of a video presentation. A user device is provided for the captioning system having a receiver operable to receive the captions together with synchronization information and a caption output circuit which is operable to output the captions at the appropriate timings defined by the synchronization information. The user device is preferably a portable hand-held device such as a mobile telephone, PDA or the like.

Abstract: There is described a communication system in which data is received by and/or transmitted to a telecommunications apparatus using an acoustic data channel. In embodiments, the data is encoded within the audio track of a media broadcast or other public broadcast. The invention has particular, but not exclusive, relevance to a cellular communication system. There are also described acoustic position detection systems for determining the position of a telecommunications apparatus.

Abstract: A bookmarking system is described for allowing users to bookmark audio and video content for sharing with other users. The system allows the bookmark to be generated with minimal user involvement, making the process as easy to use as the bookmarking of websites on a computer device. A disambiguation server is provided to disambiguate the content to be book-marked. The disambiguation server uses information from various sources to provide a number of candidates for selection by the user. Historical data and the bookmarks of other users can also be used to aid the disambiguation process.

Abstract: A data hiding system is described for hiding data within an audio signal. The system can be used for watermarking, data communications, audience surveying etc. The system hides data in an audio signal by adding artificial echoes whose polarity varies with the data to be hidden. In one embodiment, each data value is represented by a positive and a negative echo having different delays. A receiver can then remove the effects of natural echoes and/or periodicities in the audio signal by differencing measurements obtained at the different delays.

Abstract: There is described a communication system in which data is received by and/or transmitted to a telecommunications apparatus using an acoustic data channel. In embodiments, the data is encoded within the audio track of a media broadcast or other public broadcast. The invention has particular, but not exclusive, relevance to a cellular communication system. There are also described acoustic position detection systems for determining the position of a telecommunications apparatus.