Telogy Networks, Inc.

Texas Instruments Corporation

Zoran Mladenovic

Bogdan R Kosanovic

William A Mills

Edward B Morgan

Dunling Li

Manoj Sindhwani

David Alston Lide

Keith Krasnansky

John Thomas Dowdal

Gokhan Sisli

Joseph A Crupi

Piyush Shankerbhai Patel

Nagendra Kumar

Saqib Ali

Negendra Kumar

An overflow problem of LSF quantization in G.729 Annex B speech encoding which may lead to non-assignment of a codebook index. Preferred embodiments fix the problem with default or limited random variable assignments or flagging the overflow and adjusting the frame encoding such as by limiting spectral components or changing quantization targets.

Speech coder and method

A distributed intelligence conferencing system is disclosed, having a plurality of conferencing nodes to connect groups of participants to a conference. Each of the conferencing nodes provides for the connection of one or more participants to the conference. Each node includes a DSP for distributed signal processing, eliminating the need for a central processor. The node DSP has a signal measuring device for measuring a significant characteristic of the signals from each of the participants, such as power; a processing device, interconnected with the signal measuring device, for determining the relative characteristics, such as power levels, of each of the number of participant input signals; a communication device, interconnected with the processing device, for communicating the measured signal characteristics for a plurality of participant input signals to all other conferencing nodes; muting means for muting individual participant input signals so that only selected signals are transmitted over the conference bus to the other participants.

Bandwidth efficient conferencing system with distributed processing

A method for identification of memory assignment conflicts in the assignment of memory location addresses to a set of buffers. Programs run in embedded processors using buffers in a fixed storage space need to be mapped to addresses which do not overlap or create conflicts. The process of assigning start and end addresses for buffers can be tedious and error prone if performed without automation. The present invention presents a tool that automates the task of mapping the memory buffers and heaps to physical space. The tool utilizes a memory buffer allocation table created by the programer. The table designates the locations, sizes and overlays of all the buffers and heaps. The tool checks the validity of the memory map specified. If it is found to be invalid, the user is notified of the error. Otherwise, a memory table is created which will serve as 'hooks' for runtime buffer manipulation.

Microprocessor memory space allocation management

A modem-based echo cancellation enhancement for digital communications networks is provided. The effects on echo cancellation of non-linearity in a far end echo path in a digital telephone system are reduced by introduction of non-linearities into the near end signal prior to generation of the echo cancellation signal. Near end signal is sampled after linear to PCM conversion. A PCM to linear conversion is added prior to the echo canceler. The near end delay line can be provided between the converters to delay the signal as PCM samples, thereby reducing delay line memory requirements.

Digital modem echo canceler enhancement

A message-based memory system for Digital Signal Processor (DSP) storage expansion has a shared memory device connected to a number of DSPs through a packet communication bus. Each of the DSPs has a packet bus interface interconnected to the packet bus; and a messaging unit connected to the packet bus interface. The memory device interconnected to the packet bus can provide shared memory space for the DSPs to increase the amount of memory available to each DSP. The memory device can also be utilized to provide access to common information such as shared data or shared programing that may need to be run by multiple DSPs. The DSPs and the memory device communicate through the packet bus interface by generating packetized read and write requests.

Message-based memory system for DSP storage expansion

A system and method for reducing or eliminating degradation in voice transmission quality resulting from repeated or sequential compression and decompression of voice packets over one or more packet networks. When a voice connection is established between two parties on separate packet networks, the signal is often passed through a PBX and/or over PSTN lines, with the occurrence of two tandem low-bit-rate codecs used to transfer the signal and introducing degradation of voice quality. This situation arises frequently in voice-over-packet applications. The situation can also arise when a call is forwarded from one place to another. The present invention reduces the degradation associated with the transport of voice data and thereby improving the voice quality by removing one of the tandem codecs.

Apparatus and method for improving voice quality by removing tandem codecs in a voice communication link

The transport of ABCD bits in a digital packet network is facilitated by the inclusion of the ABCD bits into the RTP header of the digital packets. The ABCD bits are first placed in the unused bits of the RTP header. Redundancy of the previous ABCD bits, when applicable, is achieved by restricting the size of fields in the header to reserve space for redundant ABCD bits. The ABCD bits are placed in the reserved portions of restricted header fields.

Transporting ABCD bits using RTP

A method of discriminating noise and voice energy in a communication signal. A signal is measured in a plurality of block periods, which are sampled to obtain a measurement of the block energy value for the signal. The blocks are compared to a noise threshold and to a voice threshold to discriminate between noise and voice. The thresholds for noise and voice are periodically updated based on the minimum and maximum energy levels measured for block energies. In a preferred embodiment, the voice energy threshold and noise energy threshold values are updated according to a formula where the revised thresholds are based upon a factor of the minimum and maximum energy levels of the current block and the most recent past block and the average energy of the previous blocks. Updating of threshold levels allows for more accurate estimation of noise and voice during changes in either noise, voice or both to avoid missclassification of noise and/or voice.

Adaptive two-threshold method for discriminating noise from speech in a communication signal

In a system in which user equipment is connected to a packet network and a speech recognition application server is also connected to the packet network for performing speech recognition on speech data from the user equipment, a speech recognition system selectively performs feature extraction at a user end before transmitting speech data to be recognized. The feature extraction is performed only for speech which is to be recognized.

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Bethesda, MD, United States of America

Zoran Mladenovic