Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. The nature of the audio output devices used to render the synthesised sounds is such that the user is also able to hear real-world sounds from the environment. Under user control, a distinctive presentation effect is selectively applied to the item-related sounds emanating from a group of at least one synthesised sound source whereby to assist the user in distinguishing these sounds from the real-world sounds.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: Many modern microprocessors support parallel processing operations, such as single instruction multiple data (SIMD) operations. The present invention presents a number of ways in which maximum advantage can be taken of these operations to provide an efficient way of processing multiple data channels.

Abstract: Codeword synchronization and scrambler synchronization in a block-coded serial communications link are accomplished by (i) substituting a specific comma control codeword for a selected codeword value occurring in the output of a scrambler receiving an input data stream, and (ii) using selected polarity-independent bits of the block-coded scrambled bit stream to convey samples of the scrambler state. Inversion of received control codewords indicates polarity inversion somewhere along the link, enabling automatic polarity correction to be applied.

Abstract: Codeword synchronization and scrambler synchronization in a block-coded serial communications link are accomplished by (i) substituting a specific comma control codeword for a selected codeword value occurring in the output of a scrambler receiving an input data stream, and (ii) using selected polarity-independent bits of the block-coded scrambled bit stream to convey samples of the scrambler state. Inversion of received control codewords indicates polarity inversion somewhere along the link, enabling automatic polarity correction to be applied.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. The nature of the audio output devices used to render the synthesized sounds is such that the user is also able to hear real-world sounds from the environment. Under user control, a distinctive presentation effect is selectively applied to the item-related sounds emanating from a group of at least one synthesized sound source whereby to assist the user in distinguishing these sounds from the real-world sounds.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. An audio cursor, in the form of a synthesised sound source from which a distinctive cursor sound emanates, is movable in the audio field under user control. Upon the cursor being moved close to an item-representing sound source, a related audible indication is generated by modifying the sounds emanating from at least one of that item-representing sound source and the cursor. In one embodiment, this audible indication also indicates the current distance between the cursor and item-representing sound source and also the direction of the latter from the cursor.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. The interface is generated by apparatus that includes functionality for determining for each sound source, a rendering position at which the sound source is to be synthesized to sound in the audio field. To facilitate discrimination between the synthesized sound sources, the sound-source rendering positions are adjusted such that the audio field is dilated in a region of the audio field about a focus reference; this focus reference is, for example, the current direction of facing of the user or the position of an audio cursor in the audio field.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. A division of the audio field into segments is specified. In response to predetermined user input indicating at least one of these segments, the audibility of the synthesised sound sources in the segment concerned is changed, for example, to mute or un-mute the sound sources. The segmentation of the audio field can be set relative to the user's facing direction, to a presentation reference determined by the configuration of audio output devices used to produce the synthesised sound sources, or to any other convenient reference. This selective segment muting facilitates exploration of the audio field by the user.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. The sound sources are arranged in a cylindrical organization in the audio field and the field is preferably both displaceable along, and rotatable about, the axis of this organization. In one embodiment, the sound sources are arranged as on discrete floors of a building with only the sound sources on the current floor being audible; in this case, summary sound sources are provided in the audio field to indicate what sound sources are available above and below the current floor.

Abstract: An audio system comprises an audio source terminal 11 and a audio playback terminal 13, connected to each another by a wireless data link 14. The source terminal 11 comprises a source computer 15, and a cellular modem 17. The playback terminal 13 comprises a playback computer 19 having an internal processor 23 and an audio processor 24. Connected to the processor 23 is a cellular modem 21, an audio transducer 25, and a user control 27. Data relating to audio components, representing different services, is stored at the source terminal 11 where it is spatially processed and transmitted to the playback terminal. At the same time, each individual audio component is transmitted at a lower bit-rate than the spatially processed data, to the audio source terminal 11, whereafter it is spatially processed. Although the low bit-rate transmission causes a loss of audio quality, the positional data remains unaffected.

Abstract: In a method for encoding payload bits for transmission over communications link, data and control information are assembled into n-bit data words, where n is an even number and words for control information are constrained to have zero disparity (equal numbers of binary zero and one digits). The n-bit data words are then encoded into n+2-bit code words by adding a two-bit label; for words carrying control information the label has a value of 10. For other data words the disparity is evaluated; if it is zero, the label bits are 01; if the disparity is non-zero and opposite in sense to the running digital sum of the code words transmitted already, the label bits are 11; otherwise, the data word is inverted, and the label bits are 00.

Abstract: An interactive audio system comprises an audio source terminal 11 and a audio playback terminal 13 connected to each another by a wireless data link 14. The playback terminal 13, in this case, is in the form of a mobile telephone receiver. The source terminal 1 comprises a source computer 5 provided at some fixed network core. Connected to the playback terminal 13 is an audio transducer 15, and a user control device 17. The wireless data link 14 is established over a network connection which is set-up using an existing cellular telecommunications network (as are used in mobile telephony systems). In use, the source terminal 11 acts as a device by which the playback terminal 13 can access particular services. The presentation of available services is not performed using visual data displayed at the remote terminal, but instead, audible sound is used to present services. The services are represented by audio components which are transmitted from the audio source terminal 11 over the data link 14.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: Data are transmitted in blocks over a channel together with control signals for coordinating access to the channel. The control signals have the same values as some of the data blocks, these values being selected so that the control signals are spaced throughout the population of data block values and so that there is a greater Hamming distance between the control signal values than between the data signals. The control signals are transmitted between delimiter signals which differ from any of the data block signals, and are passed through a scrambling and encoding system in the same way as data signals, so that the spectrum of radiated electromagnetic emissions from the channel is not affected by the control signals.

Abstract: Three-level (ternary) line codes are provided for use in transmitting binary data at high data rates (e.g. 100 Mbits/s) over twisted-pair cable, without producing excessive radiated emissions at frequencies above 30 MHz. A running digital sum (RDS) is computed for a stream of ternary symbols as it is encoded; if this RDS reaches a predetermined limit, the polarity of the next following non-zero symbol is determined so as to change the RDS towards zero. In addition, if the binary data stream and the RDS satisfy another predetermined criterion, such as the RDS having a particular polarity when two or more 0 symbols have occurred, then the next non-zero symbol is determined so as to have the opposite polarity; otherwise the next non-zero symbol has the opposite polarity to the preceding non-zero symbol. The RDS limit and the predetermined criterion can be selected to obtain a desired power spectral density for the ternary signal propagating over the twisted-pair cable.

Abstract: An ion microprobe has an ion extraction arrangement formed by a pair of cone-shaped guard electrodes. The guard electrodes are positioned to lie tangentially to each other and to a planar surface from which ions are extracted with their apexes coinciding at the point of extraction. They have equal apex angles of preferably 90.degree.. An aperture is provided at the common apex and electric fields oppositely polarized with respect to each other are provided within each guard electrode for ion and electron beam extraction.