Abstract: For use in a multichannel time division multiplexed conference arrangement where the samples in one time frame of simultaneous speakers are summed for distribution to each of the conferees, the disclosed arrangement reduces the amount of speech that is often not heard (clipped) when a conferee first begins to speak. The arrangement features a delay unit which stores all the speech samples from one time frame for a period of time greater than the processing time required to detect and determine whether to include speech samples from a new speaker in the distributed sample. By first storing the samples from one time frame and then summing the stored samples, any samples from a new speaker may be included in the resulting output sample to reduce speech clipping.

Abstract: There is disclosed a linear time division multiplexed time slot conference for continuously summing and outputting digital message samples received from n connected telephone lines respective to m sequential time slots. The conferencer processes 256 time slots and uses prefetching techniques to reduce memory requirements to allow the circuit to be integrated into a single chip. Besides establishing conference-type connections, the conferencer has the capability to establish broadcast and monitor connections. Message samples collected from each connected line of a conference connection are summed during a first time frame and outputted during a second time frame. The conferencer includes circuitry for detecting either positive or negative overflow which could result from the summation process, and in this respect, selects an alternate message for outputting.

Abstract: In a digital, time division multiplex communication system, a first-in, first-out buffer (10) at each subscriber station is employed to establish a conference call. The digital words of the conferees being listened to are entered into the buffer as they are received. They are then read out at a different bit rate such that they all occupy an equal fraction of the word period. The words are decoded in a standard D/A converter (11) and combined in a filter (12).

Abstract: There is disclosed a linear time division multiplexed time slot conferencer in which a summation of incoming message samples respective to a group of time slots are stored in a summation memory during a first frame and extended to an output during a next or second frame. The conferencer processes 256 time slots and refreshes the summation memory each frame by recognizing a first access to the memory with respect to a group of time slots and directly loads a new incoming message sample over the priorly stored summation for that group.

Abstract: A digital transmission system in which bursts of digital signals are transmitted in opposite directions over a two wire telephone loop at fixed frame intervals. Each signal burst is bounded by initial and final synchronization bits at its beginning and ending respectively. Once frame synchronization is established the signals are only gated to the receiver during a window interval which is coextensive with that of the received bursts.

Abstract: A receive circuit for binary signals in time compression multiplexing systems mitigates effects of the local data decay tail and zero line wander by means of a sample-and-hold circuit, having a fast attack and a decay time constant equal to a combination of the transmission line, and dc blocking device time constants followed by a subtracting difference amplifier. Power feed of the line via dc blocking capacitors is thus possible. Also higher receiver gain is possible when sampling switch is left on during local data transmission without receiver instability.

Abstract: The system for transmitting information between a central station (SP) and sub-stations (SS1, SS2, SS3) operates, for the transmission from the sub-stations to the central station in accordance with a method (TDMA method) which consists in providing time slots in each of which only one sub-station can transmit, the arrangement of these time slots being determined by a synchronizing signal transmitted via a link from the central station to the substations; this system is characterized in that it comprises at the sub-station ends delay adjustment means (MR1, MR2, MR3 . . .

Abstract: In a circuit arrangement for time-division multiplex telecommunication systems, the signaling information transmitted over a signal channel per time-division multiplex and combined in super pulse frames is switched over the time-division multiplex switching matrix serving for the switching of message channels. Two holding memories are assigned to an information memory. One of the holding memories serves for the switching of message information and operates with a circulation cycle corresponding to a pulse frame. The other holding memory serves for switching of the signaling information and operates with a cycle corresponding to a super pulse frame. The second holding memory is advanced with each full cycle of the first holding memory.

Abstract: A digital transmission system in which bursts of digital signals are transmitted in opposite directions over a two wire telephone loop at fixed frame intervals. Each signal burst is bounded by initial and final synchronization bits at its beginning and ending respectively. Synchronization is established by determining coincidence of the final bit of one burst, the initial bit of the following burst, and two gating signals having an equivalent time interval therebetween.

Abstract: Signaling information is transmitted over a signal channel per time-division multiplex and combined into super pulse frames each of which corresponds to the duration of a larger plurality of successive pulse frames, over the time-division multiplex switching matrix serving for the switching of message channels. A first information memory has a turnover cycle corresponding to a pulse frame and serves for the intermediate storage of message sub-information, whereas a second information memory has a turnover cycle corresponding to a super pulse frame and serves for the intermediate storage of signaling sub-information. A common holding memory assigned to both information memories regularly interrupts the read operation of the first information memory for the purpose of inserting a signaling sub-information read from the second information memory.

Abstract: This circuit provides for retrieving common control interoffice signaling (CCIS) data from a PCM voice data stream of a T1 span. T1 spans interconnect switching offices. Unused data bits in these T1 spans are encoded with CCIS data and transmitted between the switching systems where the CCIS data is recovered.

Abstract: The conference circuit provides for establishing a conference call between three conferees in a T-S-T digital switching network. The voice samples of the three conferees are sequentially stored in input buffers. When all three conferees' samples are stored, the samples are transferred to working buffers, while the input buffers store three other conferees' samples. In the time slot succeeding the transfer to the working buffers, two conferees' voice samples are compared. During the next time slot, the resultant of the comparison is transmitted to the third conferee. This conference arrangement provides for time sharing up to 64 three-port conference calls via the switching network.

Abstract: In the duplex transmission of data signals over two-wire transmission paths the phenomenon of echo-signals is encountered, while simultaneously intersymbol interference occurs between the data symbols themselves. In order to reduce the influence of both the echo signals, and the intersymbol interference, the arrangement comprises a random access memory (16) which produces a correction value (c(i)) at each sampling instant to correct the received data signal. The memory is addressed from registers (13, 14) and a counter (15), the contents of the registers being determined by the data ssymbols transmitted last and the data symbols received last, respectively. A D-A converter (19) converts the correction value into a correction signal (c(t)), which in a difference producer (20) is subtracted from the received data signal. A sampling arrangement (21) samples the corrected received data signal. After D-A conversion (22) and multiplication (17) by a predetermined factor .alpha.

Abstract: An automated switching office arrangement for switching data link transmission from analog to digital data or vice versa is disclosed. Any or all of a number of data links may be automatically switched between the digital and the analog transmission modes. This automated switching may be accomplished locally within the switching office or from a remote location.

Abstract: Voice-band signals are coupled to and from a telephone subscriber line via a low-pass filter which has a shunt capacitor coupled across the line. In order to simultaneously couple above voice-band signals to and from the line, this capacitor is coupled to the line via windings of a transformer. The above voice-band signals are coupled via at least one series inductor and the transformer to the line, the inductor being series resonant with the filter capacitor, as reflected through the transformer, at the above voice-band signal frequency. Two such series inductors provide for efficient coupling of signals to and from the line at two different frequencies, facilitating simultaneous transmission and reception of above voice-band signals, for example FSK data signals, via the line. Parallel resonant circuits are also provided to prevent degradation of the filter characteristics in the voice-band and to prevent coupling of receive frequency components from the transmit signal to the receive signal line.

Abstract: Voice-band signals are coupled to and from a telephone subscriber line via a low-pass filter which has a shunt capacitor coupled across the line. In order to simultaneously couple above voice-band signals to and from the line, this capacitor is coupled to the line via windings of a transformer. The above voice-band signals are coupled via the transformer to and from the line, for example via series inductors which are series resonant with the filter capacitor, as reflected through the transformer, at above voice-band signal frequencies. A parallel resonant circuit, which has a low impedance in the voice-band, is connected in parallel with a winding of the transformer to prevent degradation of the filter characteristics in the voice-band.

Abstract: A T-carrier digital test system which actively monitors each T-carrier wire pair on a time division multiplexing basis while either live communications or test signals are on the line, and determines from the monitored data whether an incipient or hard failure of the line exists. It achieves this result by utilization of interacting devices called Scanners and Scanner Controllers. Each Scanner is housed in a repeater case and is connected to and monitors the output of each regenerative repeater in that case. The Scanner also connects to a fault line which runs in parallel to the T-Carrier wire pair and acts as the communications media and power path between several Scanners and the telecommunications facilities at each end of the cable pair.

Abstract: Asynchronous time division multiplex switching network for multi-service digital network. It comprises a plurality of time division multiplex bidirectional highways, a plurality of data transmit and receive stations connected to and associated with said bidirectional highways and a plurality of buses connecting these stations therebetween. The highways convey digital data arranged in a hybrid frame including a time slot part formed of a plurality of time slots containing sample words having a variable number of bits and a packet channel part formed of a plurality of channels for packets having a variable number of bits.

Abstract: A data transmitting system where transmission in packet form takes place between several stations includes an encoder converting signals into a transmission waveform where the low frequency components are significantly attenuated. A sub-signal, notably a voice signal from a telephone set is multiplied on the low frequency region and also transmitted between the stations.