Abstract: An audio signal compression and decompression method and apparatus that provide lossless, realtime performance. The compression/decompression method and apparatus are based on an entropy encoding technique using multiple Huffman code tables. Uncompressed audio data samples are first processed by a prediction filter which generates prediction error samples. An optimum coding table is then selected from a number of different preselected tables which have been tailored to different probability density functions of the prediction error. For each frame of prediction error samples, an entropy encoder selects the one Huffman code table which will yield the shortest encoded representation of the frame of prediction error samples. The frame of prediction error samples is then encoded using the selected Huffman code table. A block structure for the compressed data and a decoder for reconstructing the original audio signal from the compressed data are also disclosed.
Abstract: In a multi-point video conference control apparatus, a chairman demultiplexer separates video and speech signals from a multiplexed signal from a chairman CODEC. A talker demultiplexer separates video and speech signals from a selected multiplexed signal. A detecting section detects a talk request signal. A first selection instructing section instructs a first selector to select one multiplexed signal on the basis of a detected talk request signal. A second selection instructing section instructs an image selector to select the video signal from the talker demultiplexer upon detection of no talk request signal, and instructs the image selector to select the video signal from the chairman demultiplexer upon detection of no talk request signal. A multi-address calling multiplexer multiplexes the video signal from the image selector and the speech signal from a speech adder.
Abstract: A networking protocol for wireless point (base station) to multipoint (user) networks where the users are stationary which utilized time-division multiplexing the in the direction of the base station to the user, heretofore called the downstream direction, and time-division multiple access in the direction of the user to the base station, heretofore called the upstream direction, where medium access control actively assigns time slots in the upstream direction to accommodate varying demands for bandwidth by multiple users, where upstream frame timing is synchronized to the downstream frame timing, where time slots carry individual ATM cells, where the first time slot of the downstream frame carries a frame start ATM cell, where upstream time slot synchronization is maintained to within .+-.
December 5, 1995
Date of Patent:
May 12, 1998
Stanford Telecommunications, Inc.
Allan Evans, Charles Van Blaricom, April Hunter
Abstract: A data communication network for providing dynamic routing through both wireless and wired subnetworks to support wireless communication devices and wired remote stations is disclosed. In the wireless network, the wireless communication devices can be mobile RF terminals, while the wired remote stations might be personal computers attached to a wired subnet, such as an ethernet coaxial cable. The wireless network architecture utilizes a spanning tree configuration which provides for transparent bridging between wired subnets and the wireless subnets. The spanning tree configuration provides dynamic routing to and from wireless communication devices and remote stations attached to standard IEEE 802 LANs.
Abstract: A network termination (NT) with a network interface (U.sub.KO), several subscriber interfaces (S.sub.O 1, S.sub.O 2), a control unit (CPU) and an internal bus (IBUS) is indicated for a telecommunications network. Information is transmitted on the network side in a frame structure by the time division multiplex method. The frame structure contains several useful information channels and one or more signaling channels. The control unit (CPU) assigns the useful information channels to the terminals in such a way, that each terminal has at least one channel available for the transmission of useful information. In addition, the network terminations (NT) of several subscribers are combined in the circuit of a network termination arrangement (NTE) outside of the subscribers' premises, and is jointly supplied by a voltage transformer (ACDC). A power supply that is independent of the telecommunications network supplies the voltage transformer (ACDC).
May 31, 1996
Date of Patent:
December 2, 1997
Reinhard Doll, Siegfried Schmoll, Wolf Ohl
Abstract: From a stream of digital data units (10), which exhibits gaps as a result of parameter monitoring, the number of missing data units must be determined and the response time of the parameter monitoring must be estimated at the place of determination for non-conforming data units (15, 16, 17; 21). The method is based on using the identification number (12, 13, . . . ), which is carried by the data unit (10), to detect the gaps. A starting time (L12) is established with the arrival of a first conforming data unit, which is continuously updated as long as no gap occurs. After a gap is detected, the updated time (L14) of the last conforming data unit serves as the lower barrier (L) of the response time, that of the first conforming data unit (18) after the gap as the upper barrier (U) of the response time. The number of missing data units can be derived from the gap in the identification numbers. The method can be immediately continued, so that many values can be stored and used for a statistical evaluation.
Abstract: An architecture for a radio network having nodes that are subject to dynamically changing topology such as, e.g., a mobile radio network. The network is partitioned into a number of physical subnets wherein each physical subnet includes a certain number of network nodes in relatively close proximity to one another. Each node of each physical subnet is affiliated with a corresponding node of each of the other physical subnets, thus defining a certain number of virtual subnets. A desired communications path is routed from a source node of one physical subnet to a destination node of another physical subnet, by routing certain parts of the path within one or more physical subnets during a first transmission phase, and routing remaining parts of the path within one or more virtual subnets during a second transmission phase.