Abstract: A first voice channel transmits voice signals into a second voice channel through a plurality of network nodes and data links. Preferably the voice signals are in packets each having a plurality of bits containing voice information and each having at least one additional bit to indicate whether a congestion has been encountered at any of the nodes. Preferably the voice signals in each packet have a particular bandwidth and a particular compression. When a congestion of a packet is encountered at one of the nodes, the node produces at the additional bit in the packet an indication that congestion has occurred. The packet with this indication then passes through the nodes to the second channel. The second channel then produces and sends to the first channel signals acknowledging the reception of the packets and the encountering of congestion. The first channel then reduces the bandwidths of the signals in the packets transmitted to the second channel and increases the compression of the signals in the packets.

Abstract: A calling station sends to a called station a call request package including the address of the called station and the information digitizing rate of the calling station. The packet may also include the address of the calling station. The called station selects the lower of the information digitizing rates of the calling and called stations or the information digitizing rates of both stations if such rates are the same. The called station sends to the calling station a call request response package including the selected information digitizing rate. The call request response packet may include the addresses of the calling and called stations. The calling station selects the lower of the information digitizing rates of the calling and called stations or the information digitizing rates of both stations if both rates are the same. The information digitizing rates of the calling and called stations may be the voice digitizing rates of both stations.

Abstract: Symbols, each having a particular number (e.g. 9) of binary bits in first channels have individual periodicities. A symbol in each channel indicates the start and the periodicity of the symbols in that channel. Another symbol indicates the end of the symbols in that channel. The symbols from each channel are merged into sequential time slots, in a priority dependent upon the symbol periodicities in the different channels. Aperiodic symbols in second channels are merged sequentially into the time slots not occupied by the periodic symbols. Second portions (e.g. 5 bits) of the symbols in groups are provided in character frames without change. The binary bits (e.g. 4) in the first portion of each symbol in each group represent a decimal integer. The resultant decimal value is represented in the character frame by a reduced number (e.g. 10) of binary bits.

Abstract: Symbols, each having a particular number (e.g. 9) of binary bits in first channels have individual periodicities. A symbol in each channel indicates the start and the periodicity of the symbols in that channel. Another symbol indicates the end of the symbols in that channel. The symbols from each channel are merged into sequential time slots, during the occurrence of the symbols in such channel, in a priority dependent upon the symbol periodicities in the different channels. Aperiodic symbols in second channels are merged sequentially into the time slots not occupied by the periodic symbols. Second portions (e.g. 5 bits) of the symbols in groups are provided in character frames without change. The binary bits (e.g. 4) in the first portion of each symbol in each group represent a decimal integer with an individual decimal significance. The resultant decimal value is represented in the character frame by a reduced number (e.g. 10) of binary bits.

Abstract: The pitch frequency of voice signals in successive time frames at a voice coder may be determined as by (1) Cepstrum analysis (time between successive peak amplitudes in each time frame), (2) harmonic gap analysis (amplitude differences between peaks and troughs of the peak amplitude signals in the frequency spectrum) (3) harmonic matching, (4) filtering of the frequency signals in successive pairs of time frames and the performance of (1)-(3) on the filtered signals to provide pitch interpolation on the first frame in the pair and (5) pitch matching. The amplitude and phase of the pitch frequency and harmonic signals are determined by refined techniques to provide amplitude and phase signals with enhanced resolution.

Abstract: Modulated data information having an individual one of different baud rates and aural information are converted at a transmitter from analog to digital form. A controller separately identifies the digitized aural and modulated data information and, if modulated data, identifies the baud rate of such modulated data. The aural information is separately transformed. For modulated data, the information is separately processed in accordance with the different baud rates. The individual ones of aural and modulated data are then introduced to a common line for packetizing. The beginning of each packet is labelled to identify whether the packet contains aural information (such as voice or music) or modulated data (such as modem or facsimile), and, if modulated data, the particular baud rate of such information. An individual code identifies the end of each packet. The packetized information is then multiplexed in a common bus with other packetized aural and data information.