Abstract: A method of and system for facilitating synthetic stereo audio conferencing of a plurality of users over a local or wide area network (LAN/WAN). The disclosure describes a system architecture using a LAN/WAN to support synthetic audio conferencing thus allowing, at a receiving user location, for the spatially distinct virtual “placement” of the other parties involved in a conference call. This enables the user to differentiate between the various other parties and to discern which one or more of the parties are talking at any given time. In a first embodiment of the invention, both stereo synthesis and conferencing are client-based functions. In a second embodiment of the invention, both stereo synthesis and conferencing are server-based functions. In a third embodiment of the invention, stereo synthesis is a server-based function and conferencing is a hybrid client/server function using multicast.

Abstract: A method of and system for conferencing a plurality of clients over a local or wide area network using multicasting where the conferencing function is distributed between a server and the clients. The invention takes advantage of certain capabilities of existing client equipment and multicasting capabilities of the server to distribute the conference function between the server and the clients in a conference call over a LAN/WAN in a way that reduces network congestion and protocol complexity. The system of the present invention for providing conferencing over a local or wide area network, includes: a plurality of clients connected to the network for transmitting signals to and receiving signals from the network; and a server connected to the network for receiving a plurality of signals transmitted from the plurality of clients, mixing the received signals to create a single multicast signal, and transmitting the multicast signal to each of the clients.

Abstract: The present invention provides a method of and system for controlling and effectively reducing the echo introduced in telephone connections over variable delay networks such as LAN/WAN networks. The invention includes estimation of the round-trip user-to-user delay in the telephone connection. This estimation can be made in a number of different ways, including using timestamps in existing data packets according to a Real-Time Protocol (RTP) or a Real-Time Control Protocol (RTCP) and by sending timestamps in data packets according to an Internet Control Message Protocol (ICMP). The invention further includes determination of an echo control target for the telephone connection based upon the estimated user-to-user delay. This target represents the total amount of echo control required to limit the probability of objectionable echo to less than a predetermined threshold. The amount of echo control required increases as the length of the estimated user-to-user delay increases.

Abstract: An interactive subscriber telephone terminal, comprising: a display screen; a plurality of temporarily definable response/data entry keys; and local control means for selectively causing the display screen and/or the response/data entry keys to be controlled by one of: remote signals transmitted to the terminal from a telephone switching office, and the local control means.

Abstract: The invention provides for a E-Mux and a method for encapsulating/segmenting ATM cells into/from an Ethernet frame at the boundary between an ATM and an Ethernet network. An Ethernet end-station on the E-Mux is addressed using multiple MAC level identifiers, which are dynamically assigned according to the ATM virtual circuits which terminate on that end station, and have only transitory significance on the Ethernet. A unique ATM OUI identifies the frames carrying ATM-traffic.

Abstract: An interactive subscriber telephone terminal, comprising: a display screen; a plurality of temporarily definable response/data entry keys; and local control means for selectively causing the display screen and/or the response/data entry keys to be controlled by one of: remote signals transmitted to the terminal from a telephone switching office, and the local control means.

Abstract: Changes in a telephone subscriber line voltage are detected in a telephone set by supplying a voltage dependent upon the subscriber line voltage to a potential divider having first, second, and third tapping points, the second tapping point being between the first and third tapping points, and comparing the voltages at the first and third tapping points with a smoothed version of the voltage at the second tapping point to produce pulses at respective terminals when the line voltage is falling or rising. An algorithm is described for responding to the pulses to distinguish changes in hook state of another telephone connected to the same subscriber line from interfering signals. The arrangement facilitates remote release from hold and privacy indication functions for the telephone set.

Abstract: This invention relates to a dynamic photoelasticimeter with a rotating birefringent element. It comprises a laser, a birefringent plate rotatable at a constant speed, a model to be studied, a circular analyzer and a photodetector supplying signals at its output having frequency components of 2.omega. and 4.omega.. The ratio of the amplitudes of these signals supplies an indication of the phase shift .phi. (t) contributed by the model, and the phase of the signal of the frequency 4.omega. contributes information as to the orientation .theta. of the axes of the model at the point in question.The present invention provides a particularly simple and accurate dynamic photoelasticimeter.

Abstract: An ellipsometer for measuring the polarization parameters .alpha. and .lambda. of an elliptically polarized light wave. The light wave passes successively through an orientable quarter-wave plate, a birefringent plate rotatable at a constant speed .omega. and a polarizer and then impinges upon a photodetector. Reference signals having angular frequencies of 2.omega. and 4.omega. are generated, one of these signals being employed to synchronously detect the signal at the output of the photodetector by adjusting the quarter-wave plate until the synchronously detected signal component is zero, the orientation of the quarter-wave plate then corresponding to the polarization parameter .alpha.. The parameter .lambda. is obtained by measuring the phase of the component at the output of the photodetector having an angular frequency of 4.omega..The invention applies in particular to photoelasticimetry.

Abstract: An automatic two wavelength photoelasticimeter comprising, in succession, a light source for emitting light having at least two wavelengths, .lambda..sub.1 and .lambda..sub.2 ; a polarizer rotating at constant speed, an orientable quarter-wave plate of orientation .beta. with respect to a reference axis; a model to be analyzed exhibiting double-refraction and having a fast axis which forms an angle .theta. with respect to the reference axis and which provides a phase shift .phi. (which parameters .theta. and .phi. are to be measured) and three photodetectors 5, 6, and 7 preceded by analyzers 10, 11 and 12 respectively. The photodetectors 6 and 7 are preceded by filters 8 and 9 of wavelengths .lambda..sub.1 and .lambda..sub.2 respectively. The difference between the phases of the signals of the frequency 2.omega.