Abstract: Acoustic echos are canceled by employing a first echo canceler having a comparatively long first impulse response synthesis capability which is connected between a transmit path and receive path for generating a first error signal and for canceling echo signals in the transmit path, and at least a second echo canceler having a comparatively short second impulse response synthesis capability connected in parallel with the first echo canceler between the transmit and the receive path. The second echo canceler is supplied with the first error signal from the first echo canceler and is adaptively operating simultaneously with but independent of the first echo canceler to further cancel echos in the transmit path. Specifically, the first echo canceler is intended to capture the substantially stationary and any slowly varying components of the echo path impulse response, and the second echo canceler is intended to capture the more time varying, i.e., dynamically varying, component of the echo path impulse response.

Abstract: The invention conveys network related information utilizing a single bit within a data cell. This is facilitated through a statistical analysis of a plurality of such single bits collected over a period of time from multiple data cells, and provides a level of intelligence beyond a simple indication of whether or not a particular parameter has exceeded a preset threshold. Thus a switch compiling such information can convey more accurate statistical information with respect to a varying parameter related to data cells (such as queue size, current transmission rate or link utilization) being sent to the various receivers within the network. Each receiver can then apply a suitable filter to the stream of received bits to extract the appropriate information, and send that information back to the source. In response, the source adapts the transmission rate or amount of data cells being sent to the switch accordingly.

Abstract: The problem of noise enhancement is eliminated in communications systems by predistorting the amplitude of the transmitted information signal in a manner which compensates for the amplitude distortion introduced in a portion of the communications channel. In the disclosed embodiments, the communications system includes two signal transceivers which communicate with one another through a communications channel. The communications channel includes two-wire subscriber loops adjacent to each signal transceiver with a four-wire transmission path disposed between the subscriber loops. Each transceiver transmits an information signal which, depending on the system noise characteristics, is predistorted to compensate for all or a portion of the amplitude distortion introduced in a subscriber loop adjacent to that signal transceiver. The predistortion necessary to provide such compensation is determined at each transceiver in response to a received narrowband signal at that transceiver.

Abstract: Encoder/decoder buffer overflow and underflow encountered when employing actually variable or effectively variable bit-rate channels for communicating encoded video images and corresponding audio signals are overcome by adjusting the parameters of a video encoder in response to a representation of cell delay variation, i.e., jitter, determined at a remote decoder.

Abstract: Failure to cancel echos at frequencies in which the frequency characteristics of sub-band filters in the X and Y analysis filter banks overlag in subband echo cancelers is overcome by employing an X-analysis filter bank in which the pass-band of the subband filters is wider than the pass-band of the corresponding subband filters in the Y-analysis filter bank. This insures that there is sufficient energy in the tap delay lines of the adaptive filters in the subband echo cancelers at all frequencies where echos are to be synthesized. More specifically, the keeping of sufficient energy in the tap delay lines of the adaptive filters in the subband echo cancelers avoids exciting eigenmodes associated with the small eigenvalues of the correlation matrix.

Abstract: Encoder/decoder buffer overflow and underflow encountered when employing actually variable or effectively variable bit-rate channels for communicating encoded video images and corresponding audio signals are overcome by adjusting the parameters of a video encoder in response to a representation of cell delay variation, i.e., jitter, determined at a remote decoder.

Abstract: Symbols which are representative of customer data are transmitted in bursts. In the idle mode, i.e., the time intervals between bursts, symbol sequences which are a priori known to the receiver are transmitted. Such idle mode symbols maintain adaptive apparatus, such as NEXT cancellers and equalizers, in their properly converged state. To reduce crosstalk and spectral emissions, the idle mode symbols are selected to be the innermost symbols in the signal constellation encompassing the ensemble of all symbols.

Abstract: In a telecommunications management network including a network element provisioned as a so-called Directory Services Network Element (DSNE) and at least one sub-network intended to include one or more network elements, automatic registration network element identity information is realized by employing a routing exchange protocol to dynamically maintain identity information of network elements reachable within the network, enhancing the routing exchange protocol interface to automatically supply an indication of detection of a newly reachable network element to an applications layer protocol, and using the indentity information of a newly reachable network element in the applications layer protocol of the DSNE to establish communications with the newly reachable network element. Then, the newly reachable network element supplies additional identity information (e.g., its name, network address and the like) to the DSNE.

Abstract: In a telecommunications management network including a network element provisioned as a so-called Directory Services Network Element (DSNE) and at least one sub-network intended to include one or more network elements, the DSNE automatically distributes the identity information of all network elements in a sub-network to all the network elements in that sub-network. Specifically, the DSNE automatically distributes all the identity information for all network elements within a sub-network to a newly registered network element and also supplies the identity information for the newly registered network element to all the other network elements within the sub-network. Since, each sub-network can be defined as a set of network elements that require significant communications with each other, distribution of the identity information for all the network elements in the sub-network to all the network elements in that sub-network significantly reduces the number of queries made to the DSNE.

Abstract: Full channel service is obtained over a modified ISDN BRI interface by emulating at least one central office (CO) station terminal which provides access to a voice channel over a single DSL for user station terminals whether or not they are ISDN BRI compatible. To this end, an interface is provided for the DSL that emulates an ISDN BRI CO station terminal and acts like a facility to station terminals. More specifically, a plurality of CO station terminals are emulated on a single multi-point passive bus terminating the single DSL. Each of the emulated CO station terminals presents to the CO switching office the appearance of being a CO station terminal. The emulated CO station terminals are configured such that CO features are accessible. Information from the emulated CO station terminals is mapped into existing system structures where such structures are available and compatible with the information from the emulated terminal.

Abstract: The long term average broad band gains of a plurality of individual signal channels, associated with a corresponding plurality of microphone elements, are electronically and dynamically adapted to one another. This is realized by periodically and dynamically processing the signals from the individual microphone elements. More specifically, the processing is such that the long term average broad band gain of the signal channels of the individual microphone elements is dynamically adjusted, an energy estimate of each microphone signal channel is averaged over the long term and the difference in energy between the signal channels is used to readjust the long term average broad band gain of the microphone signal channels to minimize those differences.

Abstract: The quality of video images received at the remote end of an ATM network capable of transmitting data at high and low priorities is greatly improved at high cell loss levels by employing a two-layered video encoding technique that adapts the method for encoding information transmitted in the low-priority bit-stream to the rate of cell loss on the network so that compression efficiency and image quality are high when the network load is low and resiliency to cell loss is high when the network load is high. The encoder adapts its encoding method in response to a cell loss information signal generated by the remote decoder by selecting the prediction mode used to encode the low-priority bit-stream, and by changing the frequency at which slice-start synchronization codes are placed within the low-priority bit-stream.

Abstract: Full directional pickup coverage is realized by employing a pickup arrangement which provides a plurality of audio polar directivity patterns, i.e., directional beams. These polar directivity patterns are formed in a unique embodiment of the invention by generating a plurality of frequency independent time-delayed versions of a corresponding plurality of spatially sampled signals and by combining each of the plurality of spatially sampled signals with one or more selected ones of the time delayed versions to generate at least a similar plurality of polar directivity patterns. More specifically, the spatially sampled signals are combined with the delayed versions in such a manner that a greater number of polar directivity patterns can be considered than the number of spatially sampled signals. In a specific embodiment, the spatially sampled signals are acoustic (audio) and a plurality of microphones arranged in a predetermined spatial configuration is employed to obtain them.

Abstract: To reduce near-end crosstalk (NEXT) in systems possessing excess bandwidth, a signal is transmitted from a first to a second location. At the second location, the received signal is examined and a characteristic of this signal is determined while the delay provided in the transmit signal path at this location is varied. Based on this examination, a particular amount of delay is introduced into the transmit signal path which reduces NEXT. This process is repeated for each direction of transmission. In the disclosed embodiment, the characteristic of the received signal which is determined is the mean square error and the amount of delay selected is that corresponding to the minimum mean square error.

Abstract: An auxiliary baseband telephone instrument interface is provided in an answering machine to which any auxiliary telephone instrument, whether corded or cordless, can be connected and can control the answering machine functionality by use of in-band control signals. More specifically, a controllable switch arrangement is employed to connect outputs of an auxiliary instrument jack to outputs of a telephone line jack to which the answering machine is connected, or to the answering machine functionality itself and to disconnect the outputs of the auxiliary jack from the outputs of the telephone line jack or the answering machine functionality.

Abstract: ATM test cells are generated and inserted into an ATM combined data stream in such a manner that a desired average insertion rate is maintained. The desired average insertion rate is obtained by enabling generation of and insertion of test cells into each idle cell of the ATM combined data stream so long as the actual number of test cell being inserted does not exceed a number that should have been inserted.

Abstract: Misconnections between communications circuits in a bidirectional line-switched ring transmission system are essentially eliminated by deterministically squelching in adjacent ring nodes, i.e., loop-back-switching nodes, communications circuits terminated in failed ring nodes in the ring transmission system. The deterministic squelching is realized by provisioning the ring nodes with all active communications circuits including those passing through the node which are terminated in other ring nodes in the bidirectional line-switched ring transmission system. Then, when one or more adjacent ring nodes fail, all active communications circuits terminated in those failed ring nodes are squelched in the adjacent ring nodes, i.e., in the loop-back-switching ring nodes.