Abstract: A directional speaker for an electronic device having audio output capabilities is disclosed. The directional speaker can thus be used with the electronic device to direct audio output in a directionally constrained manner. As a result, a certain degree of privacy with respect to the audio output is achieved for the user of the electronic device, yet the user need not wear a headset or ear phone, or have to hold a speaker against one's ear. The directional speaker can be integral with the electronic device. Alternatively, the directional speaker can be an attachment (or peripheral) to the electronic device.

Abstract: A hearing enhancement system that enhances a user's hearing based on a directional speaker is disclosed. In one embodiment, the system can include an interface unit that has a directional speaker and a microphone. The microphone captures input audio signals that are transformed into ultrasonic signals. The speaker transmits the ultrasonic signals, which are transformed into output audio signals by interaction with air. At least a portion of the output audio signals are modified to enhance the hearing of the user. Based on the system, the user's ear remains free from any inserted objects and thus is free from annoying occlusion effects. Compared to existing hearing aids, the system is relatively inexpensive. In another embodiment, the system can also be used as a phone. In yet another embodiment, the system can also access audio signals from other portable or non-portable instruments, wired or wirelessly, such as from home entertainment units, phones, microphones at a conference or speakers at a movie theater.

Abstract: This invention describes a new method and system for delivering data over a network to a large number of clients, which may be suitable for building large-scale Video-on-Demand (VOD) systems. In current VOD systems, the client may suffer from a long latency before starting to receive the requested data that is capable of providing sufficient interactive functions, or the reverse, without significantly increasing the network load. The method utilizes two groups of data streams, one responsible for minimizing latency while the other one provides the required interactive functions. In the anti-latency data group, uniform, or non-uniform or hierarchical staggered stream intervals may be used. The system being realized based on this invention may have a relatively small startup latency while users may enjoy most of the interactive functions that are typical of video recorders including fast-forward, forward-jump, and so on.

Abstract: This invention describes a new method and system for delivering data over a network to a large number of clients, which may be suitable for building large-scale Video-on-Demand (VOD) systems. In current VOD systems, the client may suffer from a long latency before starting to receive the requested data that is capable of providing sufficient interactive functions, or the reverse, without significantly increasing the network load. The method utilizes two groups of data streams, one responsible for minimizing latency while the other one provides the required interactive functions. In the anti-latency data group, uniform, or non-uniform or hierarchical staggered stream intervals may be used. The system being realized based on this invention may have a relatively small startup latency while users may enjoy most of the interactive functions that are typical of video recorders including fast-forward, forward-jump, and so on.

Abstract: This invention describes a new method and system for delivering data over a network to a large number of clients, which may be suitable for building large-scale Video-on-Demand (VOD) systems. In current VOD systems, the client may suffer from a long latency before starting to receive the requested data that is capable of providing sufficient interactive functions, or the reverse, without significantly increasing the network load. The method utilizes two groups of data streams, one responsible for minimizing latency while the other one provides the required interactive functions. In the anti-latency data group, uniform, or non-uniform or hierarchical staggered stream intervals may be used. The system being realized based on this invention may have a relatively small startup latency while users may enjoy most of the interactive functions that are typical of video recorders including fast-forward, forward-jump, and so on.

Abstract: In a large-scale video-on-demand (VOD) system, the scalability and the provision of truly interactive functions are two difficult problems which have not been resolved satisfactorily. It is easy to provide fully interactive functions using unicast streams but these systems are limited in their scalability which affect the cost of service provisioning. Batching systems based on multicast streaming, on the other hand, can increase the scalability but it is difficult to provide interactive functions on these systems. This invention provides a media delivery system having a novel architecture aiming at serving millions of users in a metropolitan area. It features hybrid multicast-unicast streaming to achieve both scalability and full interactivity through the provision of distributed interactive servers, which cached the multicast media streams generated by the media servers. The interactive servers may also provide fault tolerant routing and error recovery.

Abstract: In a large-scale video-on-demand (VOD) system, the scalability and the provision of truly interactive functions are two difficult problems which have not been resolved satisfactorily. It is easy to provide fully interactive functions using unicast streams but these systems are limited in their scalability which affect the cost of service provisioning. Batching systems based on multicast streaming, on the other hand, can increase the scalability but it is difficult to provide interactive functions on these systems. This invention provides a media delivery system having a novel architecture aiming at serving millions of users in a metropolitan area. It features hybrid multicast-unicast streaming to achieve both scalability and full interactivity through the provision of distributed interactive servers, which cached the multicast media streams generated by the media servers. The interactive servers may also provide fault tolerant routing and error recovery.

Abstract: A distributed-queue, expanded-bus communication network and the protocol for its operation. A dual bus (42) has two counter-propagating buses (44,46) each having multiple channels (48), preferably wavelength-division multiplexed. A plurality of nodes 52 arranged along the bus receive data segments only from one each of the counter-propagating channels but can tune to any of the channel pairs for transmission. Head ends (50) at each end of the buses generate (100) formatted slots (90) upon the individual channels. Included in the format is a request field REQ and a multi-bit global request count field GRC. The head end calculates the global request count for one outgoing channel from a series of request fields received on the corresponding incoming channel. When a node has a data segment to transmit, it determines on which channel it is to be transmitted and tunes (56) to both that forward channel and the corresponding reverse channel on the other bus.

Abstract: A fiber-optic communication system in which two or more lasers of different wavelengths are modulated with respective data signals. The laser outputs are coupled to a common optical fiber. A receiving station receives all the signals on the optical fiber. A tunable acousto-optical filter in the receiving station is electrically tuned to the laser frequency carrying the desired data signal and passes only the optical signal with that frequency to an optical detector.

Abstract: A polarized semiconductive optical detector, laser, or amplifier in which the active layer includes a strained quantum well such that the strain splits the valence band so as to provide anisotropic absorption (and gain under population inversion) for two linear polarizations of light. The bands are split about the energy of the light so that the polarized device absorbs and thus detects, amplifies, or lases only one of the polarizations. To form a polarization-diversity detector, the polarized detector is set serially first on an optical waveguide, and a non-polarized or oppositely polarized detector is set serially second on the waveguide so as to detect the non-absorbed light of the other polarization. Such a polarization-diversity detector can be used to form a simple optical-disk pickup head or an array of pickup heads. A pair of such polarization diversity detectors can advantageously be comined with a 3 dB splitter and a local-oscillator laser to form a simple coherent receiver.

Abstract: An acousto-optica converter fabricated on x-cut (LiNbO.sub.3 and having an optical waveguide extending along the y-direction. An interdigital transducer is oriented at 5.degree. with respect to the y-direction in order to compensate for the acoustic walk-off on such an orientation. Such as integrated acousto-optical converter allows multiple stages of such converters so as to provide for (1) two-stage zero-frequency shifted converters and filters, (2) lasers using an acousto-optic filter as a tuning element, (3) polarization-independent converters in which the modes are divided, separately polarization converted, and recobined according to frequency, (4) and wavelength division multiplexing routing switches capable of simultaneously switching multiple channels.

Abstract: A 2.times.2 optical switching element is described. Illustratively, the switching element includes first and second inputs for receiving optical radiation and first and second outputs for transmitting optical radiation. The switching element also includes mode conversion means for selectively switching optical radiation of a specific wavelength arriving via one of the inputs to either or both ouptus by selectively controlling the conversion of the radiation at the specific wavelength from one mode to another. An N.times.N switch may be formed from an array of the 2.times.2 switching element.