Abstract: To supervise the operation of an arithmetic unit of a digital transmultiplexer intended to convert a TDM-signal into a FDM-signal and vice versa, a pilot signal is utilized as the test signal which pilot signal is also used to control the level of the received FDM-signals and is processed in the transmultiplexer. The pilot signal selection filter used for controlling the level is used, also in time-division multiplex, for selecting a component having a frequency equal to the pilot signal frequency and occurring in each of the two input and output signals of the arithmetic unit.

Abstract: A multiplex unit for multiplexing plesiochronous digital signals has a monitoring device for signalling the loss of input signals on one or more channels being multiplexed. Upon recognition of a lost signal in one or more channels, an alarm indication signal is substituted for the information signals in that channel and a synthetic justification signal is produced which replaces the justification information in such channel. The synthetic justification information gives the alarm indication signal the correct pulse repetition rate in the outgoing channel of the multiplex unit.

Abstract: In an arrangement for transmitting digital data signals between subscriber stations which are connected to a common data and control line, each subscriber station contains a clock generator with all clock generators synchronized via a common clock line. The station sending data signals switches the data during a given clock phase to the data line, and the stations receiving data likewise accept the data during a given clock phase. All clock generators are held in the given clock phase until data are accepted so that all clock generators are synchronized to the slowest clock.

Abstract: The present invention relates to a technique for increasing the rain margin of a satellite communication system which includes a satellite capable of transmitting multiple concurrent beams comprising time slot bursts in a TDMA mode. The present technique creates a small pool of TDMA time slots which are dedicated or formed at some instant of time by the rearrangement of traffic to permit the power normally transmitted in any portion of the multiple concurrent beams to be applied to one beam in a multiple fixed beam or limited scanning beam system or any portion of the beams which are directed at one ground station in a multiple unlimited scanning beam system for accessing a ground station experiencing, for example, a fade condition.

Abstract: A time division multiple access mobile communications system employing frency division multiplexing and perfect noise codes to enable utilization of the system. A central node, or repeater, is employed, with all transmissions to it being performed at a first frequency, and with the frequency division multiplexing being such that all re-transmissions from the central node are performed at a second, different frequency. The noise codes employed are of a type termed code mates having correlation functions which upon detection provide an impulse autocorrelation function. The described arrangement enables random access, or direct call-up, to be accomplished with total non-interference between users. Large improvements in signal-to-noise power ratio and in signal-to-jamming power ratio will be seen to result.

Abstract: A frame synchronization system for time division multiplexed data wherein all the time slots of the frame are considered during the course of the frame as opposed to being considered individually.The framing system comprises a first memory, e.g., a random access memory (RAM), and a second memory, e.g., a programmable read-only memory (ROM). The RAM includes respective locations corresponding to each relative bit time slot in the framing interval. The ROM includes respective locations corresponding to each correlation state in a predetermined sequence of states, respectively indicative of the number sequential bits in a given time slot matching the synchronization pattern. Each word in the ROM contains, in a link field, indicia of the ROM locations corresponding to the next state in the sequence. The ROM word also contains indicia of whether or not a correlation state has been attained indicative of the frame sync bit. Each RAM location is sequentially addressed in synchronism with the data input stream.

Abstract: It is common that communications such as telephone calls between calling and called lines be made by sharing a single communications path on a time division basis. Each call is assigned to a shared path for a short time interval, also called a time slot. It is known to interchange an input time slot to a different output time slot. Unfortunately, known time slot interchange arrangements insert an input sample in a single output time slot. The instant time slot interchanger extends an input sample onto a plurality of output time slots for broadcasting a sample through a plurality of locations. Also, the instant time slot interchanger may selectively insert an alternate message, e.g., an error message, in an output time slot.

Abstract: A multiplexing/demultiplexing bus structure for a TDMA communications system employs a mapping RAM in common equipment and a decoding device in a plurality of interface modules. The common equipment provides identical encoded information to each of the decoders in the interface modules, the decoders in each of the interface modules determining whether or not incoming or outgoing data is to be written into or read from the associated interface module. The decoders initiate a count to provide an address for the data written into or read out of a buffer in the associated interface module. The common equipment can thereby provide burst-to-burst selection of data. Burst and/or channel allocation may be changed in real time for any of the interface modules through a "demand assignment" process. A central network controller receives all capacity and destination requests for processing. The controller can then send capacity and destination assignments to network stations where they are received and decoded.

Abstract: A start-stop signal, such as a telex signal, having a stop polarity which is maintained for a period of time after a start-stop transition, is regenerated as a plurality of signal samples which are stored and then used to form an isochronous output signal. The invention resides in having unequal time intervals between the signal samples so that a range of periods of time for the stop polarity can be catered for to produce an isochronous output-signal of satisfactory duration.

Abstract: A system is disclosed which permits information received from any data terminal or telephone subscriber line at any interface to a digital network to be transmitted to any number of other terminals at any or all of the interfaces to the digital network. The system herein described also permits any terminal at any interface of the digital network to be conferenced, with up to N other terminals at any or all of the interfaces to the digital network where N can be made to depend solely upon the topology and single path transmission delay of the digital network itself. A facility is provided which is independently provisioned at every interface to the digital network and which is independently and concurrently available to any number of combinations of terminals and simplex paths at those interfaces. A broadcast capability is also provided whereby telecommunication information can be simultaneously transmitted from a source terminal to a plurality of destination terminals.

Abstract: An information handling system particularly suitable for motor vehicle use. A master station is arranged to transmit information to, and to receive and display information from, a plurality of sequentially-addressed peripheral stations. Synchronization and clock signals, as well as information control signals, are transmitted by the master station to the various peripheral stations, each of which responds to a particular information frame. An address code determines the information frame to which a given peripheral station responds. The peripheral station may control devices actuated by connection to a power bus or sensors from which information is obtained and transmitted to the master station for display.

Abstract: The main features of the present invention reside in the fact that one or more remote groups of subordinated terminal units are serially interconnected and arranged in a closed loop which is terminated at the output and input of a master unit. Each of said groups and said master unit is connected to the transmission line via a modulator and a demodulator. In order to selectively connect a pulse equipment associated with each subordinated terminal unit, and adapted for transmission of data, with the transmission line, each of said subordinated terminal units includes a switching unit, which either connects or disconnects the associated pulse equipment from the transmission line.

Abstract: An open loop TDMA communications system includes a transponder located on a spacecraft in quasi-synchronous earth orbit; a reference station periodically transmits a timing marker through said transponder to a plurality of geographically separated earth stations. Spacecraft position varies within controlled limits, and at any time the reference station has available to it information respecting the spacecraft's position. The reference station transmits, along with the timing marker, a spacecraft position index signal which is received at the geographically separated stations. Each of the stations detects the spacecraft position index signal, and based on its own geographic location, translates the spacecraft position index into a transmit timing adjustment. The transmit timing adjustment is employed to vary transmit timing from nominal and to thereby reduce the extent of the guard time used to ensure non-overlapping of bursts from the plurality of stations at the transponder.

Abstract: A digital data processing system including an interconnection for the various elements that constitute the system. Each element that connects to the interconnection is called a nexus, and each nexus in the system can communicate with other nexuses. A central clocking circuit generates timing signals that control such communications on a synchronous basis. The clocking circuit includes oscillator, control and sequencing circuits that produce phase and clocking signals that are coupled to each nexus. Each nexus contains receivers and decoders for converting the phase and clocking signals into a sequence of internal timing signals that synchronizes the operation of the nexus to transfers among the nexuses.

Abstract: Satellite communication system for speech signals located within the telephony band and one or more data signals, wherein half-duplex data traffic between ground-based stations can be effected simultaneously with, but separated from, full-duplex speech traffic between two ground-based stations. The use of a second receiver enables all ground-based stations to follow both the data traffic and the speech traffic.

Abstract: A multiloop communications system and a method of routing data between stations is disclosed. The communications system has a plurality of interconnected communications loops, each of the loops including a ring-connected set of nodes providing data flow unidirectionally from one node to the next, each of the nodes being capable of passing data through itself along its loop, extracting data from its loop or injecting data into its loop. A first subset of each loop's set of nodes are local nodes which interface a station to its respective loop. A second subset of each loop's set of nodes are gateway nodes which interface to a gateway node of another of the loops. Each of the stations has a logical address unique within the system and each of the nodes has a functional address unique within each node's respective loop.

Abstract: When one time reference distribution node is referenced to another time reference distribution node through a repeater, the same delays are put into signals transmitted from the repeater that are in signals received by the repeater. This is accomplished by introducing variable storage buffers into the paths of signals transmitted from the repeater, and by providing for their control. Since the same delays are added to signals transmitted to a node that are in the signals received from that node, the difference in signal transit times in the two directions of transmission on a duplex transmission path is minimized. Accordingly, the transit time in both directions of transmission between any pair of nodes, which are communicating through the repeater, is essentially the same, and high accuracy is maintained for time reference distribution among the nodes of an electronic network.

Abstract: A multiple-access, time-division multiplex, satellite communications system n which the uplink and downlink frequencies are the same.In each ground station, the outgoing information (be it data, encoded data or digitized samples of the voice frequency signals) are assembled into a sequence of pulses to be transmitted as a burst in the time slot assigned to that particular earth station. If there are n ground stations in the system, n.gtoreq.2, then the duration of each ground station sequence is, on the average, 1/2n times the duration of a complete frame or epoch, because for half of the epoch the satellite is in the receiving mode and the other half of the epoch the satellite is in the transmitting mode.

Abstract: Level control arrangement for frequency-division multiplex signals, comprising an amplifying device having a variable gain factor, a circuit for transposing the frequency of the multiplex signal at the output of said arrangement in order to bring the frequency of the pilot signal to a low frequency; a low-pass filter for limiting the spectrum of the transposed signal; and analog-to-digital converter in the form of a uniform delta modulator, the input whereof is connected to the output of the low-pass filter. In a code converter this delta modulation signal is converted into either a PCM signal, or a DPCM signal, and the signal thus obtained is applied to a digital filter for selecting a signal which is characteristic of said pilot signal. The filtered signal is applied to a detector for detecting the peak values. The peak values obtained are applied to a comparison device for generating an error signal which sets the value of the gain factor of the amplifying device.

Abstract: A process is disclosed for frame synchronization in a time division multiplex system which, while ensuring a high degree of synchronization reliability, requires only a small transmission capacity. In accordance with the invention, before a synchronous state is reached, a synchronization alarm (SA=1) is given and the recognition of two consecutive synchronizing words (100010) defines the beginning of a test period (P). If synchronizing words (100010) are constantly received during this test period (P), the synchronization alarm (SA=1) is disconnected. If only one single synchronizing word (100010) is not recognized during the test period (P), the synchronization alarm continues. Commencing from the synchronous state, the synchronization alarm is given if a plurality of synchronizing words are not recognized (FIGS. 3 to 6).