Abstract: Data communication apparatus including a port and a control entity. The control entity is operative to establish a connection with a remote entity over a first path and negotiate with the remote entity using in-band signaling over the first path establishment of a second path allowing the exchange of data between the data communication apparatus and the remote entity. The invention presents advantages from the standpoint of ease of implementation and bandwidth and resource savings. The use of an in-band messaging protocol to negotiate a establishment of the second path can be implemented generally in a straight forward manner. At the same time, the ability to transfer at least part of the connection to the second path avoids the drawbacks that would arise if that part of the connection were constrained to the first path. This feature allows the operator to take advantage of benefits provided by the second path but not available to the first path.

Abstract: A data communication apparatus, comprising an interface for enabling communication with a remote entity via a network and a control entity in communication with said interface. The control entity is operative to establish a packet-switched connection with the remote entity through the network and to negotiate with the remote entity using in-band signaling entry into a codec-bypass mode of operation. In this way, a codec-bypass connection, which enhances speech quality, can be established over a packet network, which reduces bandwidth.

Abstract: Data communication apparatus including a port and a control entity. The control entity is operative to establish a connection with a remote entity over a first path and negotiate with the remote entity using in-band signaling over the first path establishment of a second path allowing the exchange of data between the data communication apparatus and the remote entity. The invention presents advantages from the standpoint of ease of implementation and bandwidth and resource savings. The use of an in-band messaging protocol to negotiate a establishment of the second path can be implemented generally in a straight forward manner. At the same time, the ability to transfer at least part of the connection to the second path avoids the drawbacks that would arise if that part of the connection were constrained to the first path. This feature allows the operator to take advantage of benefits provided by the second path but not available to the first path.

Abstract: Data communication apparatus including a port and a control entity. The control entity is operative to establish a connection with a remote entity over a first path and negotiate with the remote entity using in-band signaling over the first path establishment of a second path allowing the exchange of data between the data communication apparatus and the remote entity. The invention presents advantages from the standpoint of ease of implementation and bandwidth and resource savings. The use of an in-band messaging protocol to negotiate a establishment of the second path can be implemented generally in a straight forward manner. At the same time, the ability to transfer at least part of the connection to the second path avoids the drawbacks that would arise if that part of the connection were constrained to the first path. This feature allows the operator to take advantage of benefits provided by the second path but not available to the first path.

Abstract: A data communication apparatus, comprising an interface for enabling communication with a remote entity via a network and a control entity in communication with said interface. The control entity is operative to establish a packet-switched connection with the remote entity through the network and to negotiate with the remote entity using in-band signaling entry into a codec-bypass mode of operation. In this way, a codec-bypass connection, which enhances speech quality, can be established over a packet network, which reduces bandwidth.

Abstract: Transcoder apparatus is designed to transcode a receive signal (UR) into a transmit signal (UE). For this purpose, it includes a signaling transmitting member (14) for producing a signaling message and for introducing it into the transmit signal by stealing bits from said signal. According to the invention, the signaling transmitter member (14) also comprises a tone generator (15) to add a tone signal (UTS) to the transmit signal (UE) prior to applying the signaling message to said transmit signal.

Abstract: A data communication apparatus, comprising an interface for enabling communication with a remote entity via a network and a control entity in communication with said interface. The control entity is operative to establish a packet-switched connection with the remote entity through the network and to negotiate with the remote entity using in-band signaling entry into a codec-bypass mode of operation. In this way, a codec-bypass connection, which enhances speech quality, can be established over a packet network, which reduces bandwidth.

Abstract: Data communication apparatus including a port and a control entity. The control entity is operative to establish a connection with a remote entity over a first path and negotiate with the remote entity using in-band signaling over the first path establishment of a second path allowing the exchange of data between the data communication apparatus and the remote entity. The invention presents advantages from the standpoint of ease of implementation and bandwidth and resource savings. The use of an in-band messaging protocol to negotiate a establishment of the second path can be implemented generally in a straight forward manner. At the same time, the ability to transfer at least part of the connection to the second path avoids the drawbacks that would arise if that part of the connection were constrained to the first path. This feature allows the operator to take advantage of benefits provided by the second path but not available to the first path.

Abstract: The sender includes a first source of M-ary symbols and a second source of M′-ary symbols, with M′>M>1, for example M=2, M′=8. The frames delivered by one of the sources are interleaved into successive blocks each including symbols obtained from at least two frames. Each block gives rise to a burst of modulated signal produced either by a first modulator of M-ary symbols or by a second modulator of M′-ary symbols. In response to a change of the active source, certain M-ary symbols originating from the first source are converted into M′-ary symbols to produce at least one block of M′-ary symbols submitted to the second modulator and including both symbols from at least one frame delivered by the second source and symbols obtained by conversion of M-ary symbols from at least one frame delivered by the first source.

Abstract: This invention relates to a method and an apparatus for processing digital audio signals that may reduce the signal degradation occurring when the signal is exchanged between two communication terminals equipped with vocoders in a communication network. The solution proposed by this invention is to provide a communication terminal with a vocoder including a decoder section provided with a plurality of decoding units. A switch activates a selected one of the decoding units in dependence of the format of the compressed audio signal data frames received from a remote communication terminal. This system allows the communication terminal to support a number of different speech compression formals. In order to achieve simplicity and low cost, the communication terminal is provided with a single encoding unit. This results in an asymmetric arrangement where the communication terminal has a large number of decoding units than encoding units.

Abstract: In recent years, the telecommunications industry has witnessed the proliferation of a variety of digital vocoders in order to meet bandwidth demands of different wireline and wireless communication systems. The rapid growth in the diversity of networks and the number of users of such networks is increasing the number of instances where two vocoders are placed in tandem to serve a single connection. Such arrangements of low bit-rate codecs can degrade the quality of the transmitted speech. To overcome this problem the invention provides a novel method and an apparatus for transmitting digitized voice signals in the wireless communications environment. The apparatus is capable of converting a compressed speech signal from one format to another format via an intermediate common format, thus avoiding the necessity to successively de-compress voice data to a PCM type digitization and then recompress the voice data.

Abstract: A method comprising the steps of performing a linear prediction analysis of a speech signal digitized in a series of frames divided into sub-frames, in order to determine the parameters of a short-term synthesis filter; carrying out an open loop analysis to detect voiced signal frames and determine, for each voice frame, a degree of signal voicing and a long-term prediction delay search interval containing a number of delays depending on the degree of voicing; carrying out a closed-loop predictive analysis of the speech signal to select, for at least some sub-frames of the voiced frames, a long-term prediction delay contained in the search interval and constituting a long-term synthesis filter parameter; and determining a stochastic excitation for each sub-frame, to minimize a perceptually weighted deviation between the speech signal and the stochastic excitation filtered by the long-term and short-term synthesis filters.

Abstract: A linear prediction analysis is performed for each frame of a speech signal to determine the coefficients of a short-term synthesis filter and an open-loop analysis is performed to determine a degree of frame voicing. At least one closed-loop analysis is performed for each sub-frame to determine an excitation sequence which, when applied to the short-term synthesis filter, generates a synthetic signal representative of the speech signal. Each closed-loop analysis uses the impulse response of a filter consisting of the short-term synthesis filter and a perceptual weighting filter, by truncating the impulse response to a truncation length that is no greater than the number of samples per sub-frame and is dependent on the energy distribution of the response and the degree of voicing of the frame.

Abstract: A linear prediction analysis is performed for each frame of a speech signal to determine the coefficients of a short-Term synthesis filter. For each sub-frame, an excitations sequence which, when applied to the short-term synthesis filter generates a synthetic signal representative of the speech signal, is determined by means of an iterative process in which a symmetrical matrix B.sub.n, is gradually built up with each iteration. The matrix B.sub.n is reversed with each iteration by decomposing the pattern B.sub.n =L.sub.n .multidot.R.sub.n.sup.T with L.sub.n =R.sub.n .multidot.K.sub.n where L.sub.n and R.sub.n are triangular matrices and K.sub.n is a diagonal matrix, and matrix L.sub.n has only 1s on its main diagonal.

Abstract: The input acoustic signal is subjected to high-pass filtering. The energy of the high-pass filtered signal is compared with that of the unfiltered signal in order to determine a state of the signal from among a first state for which the energy of the high-pass filtered signal is above a predetermined fraction of the energy of the unfiltered signal and a second state for which the energy of the high-pass filtered signal is below the predetermined fraction of the energy of the unfiltered signal. The high-pass filtered signal subjected to pre-emphasis of the high frequencies is addressed to the input of the coder when the signal is in its second state.

Abstract: A speech signal digitized as successive frames is subjected to analysis-by-synthesis in order to obtain, for each frame, quantization values of synthesis parameters allowing reconstruction of an estimate of the speech signal. The analysis-by-synthesis includes short-term linear prediction of the speech signal in order to determine the quantization values of the coefficients of a short-term synthesis filter. A spectral state of the speech signal is determined from among first and second states such that the signal contains proportionally less energy at the low frequencies in the first state than in the second state, and one or the other of two modes of quantization is applied to obtain the quantization values of the coefficients of the short-term synthesis filter depending on the determined spectral state of the speech signal.