Abstract: A Time-Division Multiple Access (TDMA) synchronization system for a satellite relay system is provided by designating one of the ground stations a "Reference" station and arranging for a sinusoidal signal transmitted from the reference station to be received by other ground stations via the satellite and compared with their own sinusoidal synchronization signals after transmission to and from the satellite. The sinusoidal signal from the "Reference" station uses only a small proportion of the bandwidth of a satellite global beam transponder. Most of the traffic is transmitted to one or more spot beam transponders of the satellite. Each station derives from its symbol-rate clock a pulse indicating the start of each TDMA frame and a local synchronization sinusoidal signal at the frame repetition frequency. The phase of this local sinusoidal signal is such that its positive-going zero crossings coincide with the frame-start pulses.

Abstract: In a pulse code modulation communication system in which in each station the local oscillator frequency is controlled by the difference between the aligner fills at the ends of each link coupled to the particular station, a balanced modifier can be applied periodically to the aligner fills at the ends of a link to make the fills symmetrically disposed about a mid range value and/or a straight modifier can be applied periodically to an aligner fill in the particular station to make the aligner fill equal to the mid range value, the modifiers preventing the establishment of falsely synchronized modes among the oscillators of the system.

Abstract: A delta modulator produces a digital bit stream from an input analog waveform and applies same to bit-averaging circuitry dividing the bit stream into time-frame intervals and computing the average slope per frame. Each average time-frame slope value is transmitted over a communication system as a discrete digital signal and at a receiver each such signal is employed to set the gain of a multi-level integrator and thus incrementally reconstruct the original waveform.

Abstract: Apparatus for multiplexing a large number of digital signals onto a few aog channels using a level code encoded multiplexer. Each digital signal to be multiplexed is assigned a unique reference level to represent a logical "one", with all digital inputs assigned the same zero ground as a base line for a logical "zero".

Abstract: A test unit for testing the wiring connections in modular telephone installations. The unit consists of a housing with an input jack to receive the standard plug used to connect the telephone wiring to a handset. The jack has four terminals, one pair corresponding to the green and red(tip-ring) line wires, and the other pair corresponding to the yellow and black (ground and lamp a.c.) line wires. The tip-ring terminals are connected in the housing through a first diode, a Zener diode and a resistor to a "tip-ring" L.E.D. The a.c. terminals are connected in the housing to a "lamp" L.E.D. through a diode and a transistor, controlled by a network including a blocking capacitor. When the telephone line plug is inserted in the test unit jack, the "tip-ring" L.E.D. will light only if the "tip-ring" line voltage is correct in magnitude and polarity, and the tip ring line conductors have not been interchanged with the a.c. line conductors. The "lamp" L.E.D. will light to indicate proper a.c. voltage on the a.c.

Abstract: Highly portable apparatus enabling locating cutting and splicing of an active circuit communications pair extending between two locations without circuit interruption is disclosed. The apparatus includes a master unit at one of the locations connected to the pair to be spliced and an alternate pair extending between the locations. A remote unit at the other location is connected to the active pair and the alternate pair. A pair identification and connection verification circuit is included for verifying the interconnection of the master unit and the remote unit to the same active pair. Manually actuated switching circuitry is included in the master unit for connecting the alternate pair to the active pair and for generating a switching signal which is transmitted to the remote unit upon manual actuation of the switch in the master unit. Automatic switching circuitry in the remote unit connects the alternate pair to the active pair in response to the switching signal.

Abstract: The structure described is a switching-processing node for high speed data transmission systems. Information is transmitted in time slot channels, one of which is control information. Data to be passed through a node is stripped of control characters, passed to a transmitting unit and there re-encoded with such additional data bits as needed. Data for the node is switched from an input decoder to a processor input and data for transmission is switched to a transmission unit for encoding.A switching information control frame can be passed over the system to set the switching circuits at a node to operate at the appropriate time slots of the data frames.

Abstract: A signaling extraction circuit utilizes common control circuitry to carry out the signal extraction function for all of a plurality of time multiplexed, digital data groups (digroups), each of which comprises 24 time division multiplexed, PCM encoded channels. Each digroup uses eight bits for transmitting digital information for each channel, but the eighth bit (D8) is borrowed for signaling purposes in every sixth frame. To identify these signaling digits, signaling frame information is inserted in a digroup bit stream in the framing bit position of every other frame (i.e., the subframes). A signaling subframe pattern store comprising a shared recirculating memory serves to maintain a continuing real time record of the pattern of the signaling framing information for each digroup, as well as a test digroup. When a predetermined pattern has been recorded for a digroup (i.e.

Abstract: TNR (Traffic Noise Ratio) is defined as the ratio of the portion of the noise representing a multi-channel signal that occurs in a narrow bandwidth (including inherent, and intermodulation) to the noise in the same bandwidth, in the absence of a traffic signal in that bandwidth, under specified traffic conditions. The TNR of a communications link is measured by measuring the noise power level in a predetermined bandwidth in a quiet channel with reference to a signal representative of the power that would be in the quiet channel if it was loaded under peak traffic conditions. The noise power level is measured using a digitally stepped automatic attenuator controlled by a feedback loop which includes filters for isolating the noise in the quiet channel.

Abstract: A synchronization arrangement for a TDM concentrator in which phase differences between the transmission line clock and the internal concentrator clock are compensated for by lengthening or shortening a signalling channel (Ksynch).

Abstract: A multiplex signal transmission device for use in a multiplex communication system based on a time sharing method, which device comprises a transmitter and a receiver each having a counter circuit respectively for generating address signals in response to timing signals generated by an oscillator. Signals are transmitted from the transmitter to the receiver as a level signal at a time position of the address signal which is allotted to the signal to be transmitted.

Abstract: RC low-pass and high-pass filters are fed in common with a demodulated broadcast signal through a noise blanking switch device and the outputs of the respective filters are added in a summing amplifier, of which the output is supplied to the low-frequency stages of the receiver. For stereo reception, the crossover between the filters is made lower than the lowest pilot frequency of the composite demodulated signal, so that the circuit functions as an all-pass filter in the absence of disturbances and stores only the audible frequency program signal for transmission to the low-frequency stages during blanking intervals.

Abstract: A switching network provides interconnections for time division channels utilizing a folded space-time-space network. The network modifies the ratios of operation frequency between space division switches and time division switches to increase the efficiency of transmission while minimizing the total volume of equipment.

Abstract: In a time division multiplexed loop communication system, a plurality of terminals share one or more channels of a multichannel frame, with a second plurality of terminals assigned to different channels. The communications controller may dedicate one or more of the channels to one of the terminals automatically and dynamically. Alternatively, one of a plurality of terminals assigned to a particular channel group can interrupt the controller and become automatically selected for communication.

Abstract: A TDM switching network for a communication system having 17 input transmission lines for carrying TDM digital signals in 64 input channels on each input line and having 15 output transmission lines for carrying TDM digital signals in 64 output channels on each output line. The TDM switching network establishes connections between selected input and output channels in accordance with address instructions having A and B address segments each designating a particular channel of a particular transmission line. The switching network includes 15 switching matrices (plus a spare). Each matrix is connected to all 17 of the input transmission lines and to a different one of the output transmission lines. Each switching matrix includes a data memory which can store a data bit for each channel of each transmission line. Each matrix also includes an address memory which can store an address segment for each channel of the associated output transmission line at a corresponding storage location.

Abstract: A traffic analysis system is disclosed which utilizes a scanner to provide the identity of the trunk group within which a call attempt has occurred. The trunk group identity information from the scanner is supplied to a multiplexer which makes available four, 8-bit words based on the trunk identity information from the scanner. A micro-processor is coupled to the multiplexer and upon the occurrence of a call attempt the micro-processor adds the four words from the multiplexer, the sum of these words yielding the address of the proper storage location in a memory unit for storing the call attempt indication.

Abstract: Switching criteria are transmitted over a plurality of trunk lines to a central office of a telecommunication system in the form of a set of binary signals modulated on three carriers for each trunk line, the triads of carriers being cyclically sampled and demodulated. During each sampling interval t.sub.i allocated to a particular trunk G.sub.i within a cycle, a locally generated identification code of that trunk is transmitted to each of three sections of a read-only memory MS, each memory section permanently storing four different threshold values for the length of "on" signals (1) and "off" signals (0). Integrators IN, rejecting spurious changeovers from one type of signal to the other, feed respective counters CT via respective coincidence circuits CFR which receive from a register MG the bits of the preceding cycle and reset arithmetic units .sigma.

Abstract: A time division digital switching network comprises first multiplexing means in which first-order digital data channels transmitting words consisting of a given number of bits and having first rates which are different from but multiples of one another undergo a first multiplexing converting them into a second-order digital data channels having a second predetermined rate. Thereafter there are provided second multiplexing means in which the second-order digital channels undergo a second multiplexing converting them into third-order digital data channels having a third predetermined rate. In a digital switching unit having at least one buffer store, the first-order-channel words multiplexed into the third-order channels are grouped at an address whose first part depends upon the second-order channel they occupy in the third-order channel and whose second part depends upon the first-order channel they occupy in the second-order channel.

Abstract: A device for suppressing a pilot wave in a spectrum of frequencies by subtraction of an auxiliary frequency adjusted in frequency, in phase, and in amplitude to adequate values, used in frequency multiplex telephone transmission systems, containing two pilot frequencies in cases where maintaining either one or several of these frequencies would lead to disturbances.

Abstract: A closed loop transmission system is described in which a plurality of stations have access to each loop to write messages into and read messages from standard-sized message blocks transmitted around the loop. One station in each loop provides regeneration of all message blocks. The various loops are interconnected by switching stations which respond to address information at the head of each message block to selectively switch the block to the interconnected loop. The next required address is always substituted for the current address to simplify address recognition. Alternate and redundant routing are also provided for.