U.S. Philips Corporation

Ulrich R Killat

Johann E Kruger

Wolfgang E Jasmer

Hans O Dammann

Gert Rabe

Hans J Schmitt

Dieter A Riekmann

Rolf Stecher

In the framework of the development of future, integrated wideband networks, specifically the arrangement of the switching networks and switching network controls is of particular importance. In a switching network arranged in accordance with a space-division multiplex switching network each switching point comprises a comparator, comparing the addresses of the trunk lines arranged column-by-column to the routing information. When there is multiple correspondence in a column a decision circuit assigned to the trunk line decides the order in which the switching points are to switch. In addition, an input buffer is connected to each supply line, in which buffer the blocks are temporatily stored until they can reach one of the trunk lines. To avoid the occurrence of bottle-necks in the performance of the switching network an input buffer is assigned to each switching point or the switching network is arranged column-by-column and built up of units of equal structure.

Switching network and switching network control for a transmission system

In broadband space-division switching networks a multi-layer p.c. board is used for wiring the switching matrices of adjacent switching stages. In case of a plurality of links between the switching matrices a corresponding number of layers of the p.c. board can be provided. The connection of the individual layers of the p.c. board requires much expenditure in point of manufacturing engineering. This expenditure can be reduced in a surprisingly simple manner, when a canonical linkage in a p.c. board is introduced such, that link sections of the switching matrix are fanned out into groups onto a layer of the p.c. board and combined again. By dividing the links into sections, requirements as regards equal line length, reduction of space required and replacement in case of defects can be met in a simple manner.

Broadband space-division switching network with linkage in a printed

The invention relates to a switching network for a communication system, comprising m/1 stages and in which cells are transmitted in accordance with a time-division multiple access method and the switching is effected on the basis of the routing information contained in the header. The arriving cells are temporarily stored in a buffer until a free frame is available. The queues built up in the buffers of the m/1 stages are to be processed in the most fair manner. For this purpose it is proposed to assign a memory to each m/1 stage of each auxiliary line (Zl . . . Zm), to which memory are applied the results of the comparisons between routing information and address of the trunk line (A) and to determine for the decision circuits the order in which the cells stored in the buffers (B) are read out.

Packet switching network for a communication system

The invention relates to a switching network for a switching system in which cells are transmitted in accordance with a time division multiplex method and the through-connection is effected by means of the routing information contained in the header of the cells. The blocks arriving at the switching node are temporarily stored in a queuing buffer until a free frame is available. A switching network should be configured in such a manner that the number of buffer spaces can become as small as possible and buffer spaces only need to be provided for data which are to be forwarded via the associated serving trunk. To this end, it is proposed to allocate a comparator to each offering trunk, the comparator comparing the address of the serving trunk with the routing information and the cells supplied in the offering trunk only being entered into the buffer store associated with the serving trunk in the case of a correspondence between routing information and stored address of this serving trunk.

Switching network for a switching system

In a switching system, more specifically a packet switching system, the flow control of the packets can be established by way of a datagram or by implementing the method of the virtual connection. For the optimization of the flow control the selected structure of the switching network is especially important. If the switching network is designed along the lines of a space-division multiplex switching network, each junction point of the bus bar system consisting of feeder lines and trunk lines has a comparator assigned thereto, which compares the addresses of the trunk lines arranged in columns with the routing information contained in the packet message headers. If, simultaneously, several of the auxiliary lines arranged in rows are to be connected through to one of the trunk lines arranged in a column, the order is determined by means of a decision circuit associated to each trunk line. If the order is determined by the spatial arrangement of the feeder lines, each decision circuit cyclically scans all comparators associated thereto, so that a new evaluation of the routing information is not achieved until the complete cycle has finished.

Method of and circuit arrangement for controlling a switching network in

Large-scale time-division switching arrangements often consist of a central switching network and a series of so-called concentrators. For establishing an H1 switching a series of wideband concentrators are connected to a central wideband switching network if the wideband concentrators are of a modular structure and communicate through an internal bus system and an interface circuit with the central wideband switching network connected thereto, a distribution switching in the direction of the subscriber station and a testing of the concentrators while in operation can be effected in a simple way.

Shared lines equipment, especially for B-ISDN switching system

A buffer memory for an input line of a digital interface serves to adapt input data which exhibit large phase fluctuations with respect to the local clock of the interface to this local clock. To this end it is necessary to write the input data with the associated clock into the buffer, the data being read with the local clock. Depending on the phase shifts, write and read operation are then liable to occur simultaneously in border cases. In order to enable the use of conventional components in spite of the described phenomenon, the buffer memory is composed of a number of storage blocks which each comprise the same number of addresses, the storage blocks normally being cyclically addressed in succession. An address spacing monitoring device ensures that read and write operations are always performed only in different storage blocks, so that they can take place simultaneously. When the spacing between read and write operations becomes less than the number of address positions of a storage block due to prolonged, large phase fluctuations so that there is a risk of simultaneous read and write operations within the same block, a read address jump is made in order to address a next or a preceding storage block so that the address is increased again. This address jump takes place only at or directly after the changing over of notably the read address from one storage block to another.

Buffer memory for an input line of a digital interface

The invention relates to an optical wavelength multiplexing and/or demultiplexing device. The device comprises a digital phase grating having at least four steps. The grating diffracts light of at least three different wavelengths in different central diffraction orders. Since the grating period may be high in comparison with the wavelengths light-emitting diodes may be used as light sources.

Optical wavelength-multiplexing and/or demultiplexing device

An optical power divider for use with one incoming and a plurality of outgoing glass fibers includes an imaging device arranged on an optical axis between the incoming and outgoing glass fibers. At least one plane binary phase grating is disposed in the pupil of the imaging device. The grating is one-dimensional, has a duty factor of at least substantially 1:1, and has an optical path difference of at least substantially

Optical power divider

Method the transmission of data packets in a TDM transmission loop wherein the frame is subdivided into several groups each having the same number of words, and each group comprises either exclusively narrow-band channels for the transmission of speech data or is associated with the high-rate channel for groups comprising narrow-band channels always comprises an unambiguous bit sample of, for example, the highest priority is assigned to each group. When a subscriber station wants access to a word group in the high-rate channel it transmits its own identifying bit sample and possibly priority data in a signaling word. When this bit sample is returned through the loop undisturbed the subscriber station immediately accesses the assigned group of words in the high-rate channel for the transmission of a data packet. Allocation of channel access among individual subscriber stations is prioritized. The bit samples identifying groups comprising narrow-band channels receive the highest priority, so that these channels are automatically protected from access as a high-rate channel. A central control unit can increase the number of narrow-band channels by transmitting a further group of identifying bit samples in the signaling word.

Method of and arrangement for controlling access to a time-division

For recognizing a binary word in a bit stream in the form of light pulses in an optical conductor, the light signals arriving are distributed among a number of optical conductors. The number of conductors is equal to the number of bits of the word to be recognized. The optical conductors have a length which is stepped in unit steps according to the bit distance in the bit stream, so that the delay in each conductor is equal to the time between the bit associated with this light conductor and the last bit of the word. The ends associated with optical conductors of the one bit value are connected to a photodetector. The ends of the other optical conductors are connected to a second photodetector. A differential amplifier determines the difference between the two output signals. When the difference is maximum, the word has been recognized.

Device for recognizing a binary word

The record carrier according to the invention comprises a substrate on which an electrode is provided which, on the side remote from the substrate, has a low-ohmic photoconductive layer which is covered with a second transparent electrode which is provided wihh a thermoplastic layer. For storing information the electrodes are connected to a voltage source and the thermoplastic layer is charged electrostatically and exposed in known manner. Upon exposure of an area of the thermoplastic layer, the light will fall through the transparent electrode on the low-ohmic photoconductive layer. As a result of the current passage, Joulean heat is produced which heats the thermoplastic layer in the place of the exposed area and softens it thereby deforming the layer by electrostatic forces in accordance with the charge. The thermoplastic layer may, in known manner, also have photoconductive properties or be provided with a further photoconductive layer.

Record carrier for deformation images

A device for coupling a first optical signal of a first wavelength into a transmission glass-fiber and for coupling a second optical signal, which has a second wavelength which differs from the first wavelength, out of the fiber. The two signals travel in the transmission glass-fiber in opposite directions. The optical signals also travel in other, spatially separated glass fibers. The device includes an imaging device arranged between the transmission glass-fiber and the other glass fibers. In the pupil of the imaging device, a binary optical grating is disposed. Other glass fibers receive the second optical signals which have been diffracted into the diffractions orders of the grating. The grating is a phase grating and is arranged on an optical axis of the imaging device. It has a duty factor of at least substantially 1:1 as well as an optical path difference, H=(n-1)h, which is substantially

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Hamburg, Germany

Ulrich R Killat