DE1254716B - Time division multiplexed messaging system - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

H 04 j

German KL: 21 a4 - 49

Number: 1 254 716

File number: S 101 519 IX d / 21 a4

Filing date: January 19, 1966

Opening day: November 23, 1967

The central facilities, for example telephone exchanges, of such messaging systems have the Task, the optional connection between any terminals, z. B. telephone subscribers, if possible easy and quick to manufacture. In addition to the usual ones built with electromechanical selectors Mediations have also become known in recent years, where the mediation in the central facilities with time distribution with the aid of so-called time division multiplex busbars is carried out. These devices work at least in telephone systems purely electronic. In this case, a larger number of terminals and their connections are above electronic switches on a common busbar. To establish a connection will be the corresponding switches in phase in the rhythm of at least twice the highest signal frequency (Sampling frequency) switched through for a short time. Depending on the size of the sampling period on the one hand and the duration of a connection on the other hand can be sufficient taking into account the required Crosstalk attenuation a larger or smaller number of connections over a busbar be guided. Each connection is assigned a separate phase in which the The message is transmitted by exchanging amplitude samples, i.e. the message transmission in the area of time-division multiplex busbars, this is done in the form of pulse amplitude modulation carried out.

Is the number of a central facility assigned to terminals so large that between them Connections to be carried out are no longer carried out by a single time division multiplex busbar can be, the central facility for two or more interconnected time division multiplex busbars be interpreted. During the interconnection of two and more time division multiplex busbars in a central facility in a simple manner for pulse-amplitude-modulated operation can be carried out, considerable difficulties arise when the one another connecting facilities, as is the case, for example, at different telephone exchanges, are at a greater spatial distance from each other.

The invention is based on the object for the connection of, in particular, spatially separated central facilities in a communication system of the type described in the introduction, a simple solution to specify.

Time division multiplex message transmission system

Applicant:

Siemens Aktiengesellschaft, Berlin and Munich, Munich 2, Witteisbacherplatz 2

Named as inventor:

Dipl.-Ing. Hans-Martin Christiansen,

Munich-Solln;

Dipl.-Ing. Max Schlichte, Munich

Starting from a message system, in particular a telephone system, consisting of central Facilities for a large number of terminals connected with this via individual channels, in which the optional connection of the terminals by time division multiplex busbars in the respectively assigned to them central facilities is made, this object is achieved according to the invention solved that the switching between the terminals assigned to the various central facilities are, by time division multiplex systems with a suitable for the transmission of the signals over cables Modulation takes place between the time division multiplex busbars of the central facilities concerned are connected via switching devices operated in the rhythm of the channel repetition frequency, and that in the connection path from the receiving-side output of the time division multiplex systems to the Time-division multiplex busbars intermediate storage are arranged, whose the individual channels of the time division multiplex systems allocated storage units on the input and output side one after the other in rhythm the channel repetition frequency actuated switches are parallel to each other.

The invention is based on the knowledge that the pulse amplitude-modulated form with which the from incoming signals to the terminals are switched through by means of the time division multiplex busbars, for the interconnection of spatially separated central facilities not practically feasible is significant because pulse amplitude modulated signals are already being transmitted over very short cable routes be deformed, d. This means that the pulses of different channels flow into one another, so that on the A clean separation is no longer possible on the receiving side.

709 689/171

3 4

In principle, there would be the possibility of switching in the telephone exchanges, there are between

pulse amplitude modulated signals for transmission see the time division multiplex busbars of an office

via cable lines in low-frequency signals back "and the participants assigned to them two-wire

to convert them to the next central connections. In this case the switching

Set up again in pulse-amplitude-modulated Si devices as fork circuits (time fork).

signals for further through-connection via time multi-feed in order to make the necessary adjustment of the partial

to implement plex collective writing. The technical two-wire connection on the receiver side to the

However, the effort required for this is extremely high;

because one double line and one to the manure are possible for each channel.

another for the implementation at the two ends of the io to the switching through of the amplitude modulating cable route a low-pass filter each is necessary. The effort th signals without additional amplifier devices will not be less, if to be able to carry out savings as loss-free as possible, it is Lines several channels carrier-frequency together - expediently, the switching devices with after to get nabbed. In this case, switches operating on the resonance transfer principle are set up of the low-pass filters at each connection end 15. This principle can also be used in advantageous bandpasses, who made use of the necessary mutual adherence at the time forks Ensure the signal-to-noise ratio between the individual channels. In a preferred embodiment deliver, require a lot of effort. In addition, the timing forks are T-links, where the cross points it is a disadvantage here that the cable attenuator from the series connection with an inductance especially if there is more than a capacity in the higher frequency range, which is one of the elimination of the carried channels only very short cable sections with no residual charge of the capacity after a completed Allow intermediate reinforcement. Charge exchange serving first switch in parallel

On the other hand, the situation then turns out to be. The busbar-side longitudinal branch of the

Considerably cheaper if the connection between T-links is a second switch during the

spatially separated central facilities according to 25 series branch on the part of the time division multiplex systems in

of the invention by time division multiplex systems with a sending and a receiving fork arm

is suitable for the transmission of signals via cables, of which the fork on the transmitter side

modulation takes place, because then the arm consists of a third switch and the

the time-division multiplex busbars caused the time-catching fork arm of the parallel to each other

Bundling of the signals to be switched through for the 30 arranged output-side switches of the storage

Time division multiplex systems made direct use of chereinheiten the buffer memory is formed.

can be. In addition, the time- The number of connections on a busbar

multiplex systems a simple intermediate storage determine the switching cycle of the switching devices,

of the signals transmitted by them on the receiver via which the time division multiplex systems to the collective

catch side and thus a particularly simple solution 35 rails are turned on. Do you need this switching

the problem of mutual synchronization of the devices, such as the one after the

central facilities connected to them. The time forks of the

Time-division multiplex systems are particularly suitable with case is, intermediate clocks, then the case can occur

Pulse phase modulation, as the phase modulated that of the interference-free transmission of the

Pulses only have low low-frequency components 40 consecutive amplitude-modulated signal

and therefore the relatively large delay time impulses given maximum switching cycle is smaller than

at low frequencies the for the transmission server for the signal transmission all to the

used cables do not come into play here. Busbar of connected terminals required

Such a time division multiplex system is expediently borrowed. Here it is then appropriate to make the connection Combine one behind the other in the transmission direction on the transmission side 45 between two time division multiplex busbars Presser, one of the amplitude-modulated different central facilities pulse converts two or more channel groups into phase-modulated pulses with group-wise Modulation converter and, on the receiving side, one that composes the modulation and demodulation to provide phase-modulated pulses in amplitude-modulated time division multiplex systems, its individual Pulse back-converting modulation converter and 50 groups, whose channels for transmission like a Stretchers on. in turn to one that encompasses all groups

Advantageous transmission properties are also provided by the combination of pulse frames, in each case via a switching device to the time division multiplex that is specific to time division multiplex systems with pulse code modulation. Here, the time division multiplex systems have purpose-built busbars to be connected. In this case, the switching devices for the individual channel side send a press, a group in the pulse frame that converts the amplitude-modulated groups in the specified order of the channel pulses into phase-modulated pulses in succession in the rhythm of the first modulation converter, one of the phase-modulating channel repetition frequency to operate
The storage units of the buffers can be modulation converters and, at the receiving end, one of the capacitors can simply be capacitors. If code characters are converted back into amplitude-modulated pulses, the switching devices are built up with the generally pre-converting modulation converter and a resonance transfer switch that draws in an expander. the capacitors are useful in the

The output-side switches of the storage units with the necessary resonance system with

the cache can easily be referenced in 65,

the switching devices are included. Due to the intermediate storage, it is extremely

The connection is possible in numerous possible applications, in particular borrowed in an advantageous manner

especially in telephone systems with electronic between two busbars of different central

traler facilities on the time division multiplex system, even if the tax file for the switches at the various central facilities not only with regard to the phase, but also differ slightly in frequency from each other. Because of the different frequency of the control clock between the central facilities occur, provided the storage units . the buffer stores are each formed from a capacitor, in addition to the message signal band Sidebands that are equal to the slip frequency and its harmonics. However, this disorder is negligible as long as the slip frequency remains small enough and prevents it from going to zero will. Otherwise it is expedient to use the storage units of the intermediate storage as low-pass rc elements to train.

In the following, the invention will now be based on the embodiments shown in the drawing will be explained in more detail. In the drawing means

F i g. 1 shows the block diagram of a connection between the time division multiplex busbars of two spatially separated central facilities according to the invention,

F i g. 2 shows the block diagram of a time division multiplex system for one transmission direction according to the invention,

F i g. 3 shows a further block diagram of a time division multiplex system for a transmission direction according to FIG the invention,

F i g. 4 shows a time diagram of the switching functions of the various switches in the exemplary embodiment according to FIG. 1.

In the case of the FIG. 1 shows a circuit diagram of a time-bundled connection between two electronic telephone exchanges, one office is designated with A and the other office with B. Each of the two offices has a time-division multiplex busbar Ls or Ls' to which the remote subscribers are connected via a two-wire connection through switches ill, s 12 ... sIn or ill ', sIT ... sin' . The time division multiplex system that establishes the connection between the two offices consists in each transmission direction of a modulation converter circuit MWS or MWS 'on the transmit side and another modulation converter circuit MWE' or MWE on the receive side, which is followed by a buffer.

Each of the two buffers at the receiving end has a number of storage units SpI... Spη or SpV.. . . s6n or s61 ', s62'. . . s6n ' are connected in parallel to the output of the modulation converter circuit MWE or MWE' at the receiving end.

The transition from the subscriber-side two-wire connection to the four-wire connection representing the time-division multiplex system takes place with the aid of time forks which connect the time-division multiplex system in the exchange A or B to the time-division multiplex busbar Ls or Ls' . According to their structure, they can be viewed as T-members, in which the cross member consists of the series connection of the transfer inductance Lo or Lo ' with the capacitor Co or Co' , which is responsible for eliminating the residual charge of the capacitor Co or Co ' in Connection to a completed charge exchange serving switch 3 or 53 'is parallel. The switch s 2 or si ' represents the busbar side. The fork arm on the transmitter side is in turn formed by a switch s 4 or s 4 ' . The receiving-side fork arm is already part of the receiving-side buffer, as it is of the

ίο Sum of the output-side switches s 51, s52 ... s5n or j51 ', s 52' ... s Sn 'of the storage units SpI ... Spη or Sp V, which are arranged parallel to one another. . .Spn 'is formed.

As the F i g. 1 also reveals is in the course of the transmission line between the send and on the receiving side modulation converter circuits in a broken line another with Li? designated Arrangement shown. It is intended to provide the intermediary required for a greater length of the transmission line Indicate line regenerators.

For a preferred exemplary embodiment of a time division multiplex system with pulse phase modulation, FIG. 2 an expedient embodiment for one transmission direction is also shown in the block diagram. In this case, the modulation converter circuit MWS on the transmission side has a presser P on the input side, to which the pulse modulation converter M1, which converts the amplitude-modulated pulses into phase-modulated pulses, is connected.

After the phase-modulated pulses have been transmitted over the path, in which line generators LR are switched on, they are converted into amplitude-modulated pulses on the receiving side in the pulse modulation converter MV and passed on to the busbar of the relevant office after passing through an adjoining stretcher D. The presser P on the transmitter side and the stretcher D on the receiver side serve to improve the signal-to-noise ratio of the transmitted signal.

A further advantageous exemplary embodiment for a time division multiplex system which works with pulse code modulation is also shown for one direction of transmission in the form of a block diagram in FIG. 3 shown. In terms of structure, it differs from the time division multiplex system according to FIG. 2 on the transmitting side by a second pulse modulation converter M 2 connected downstream of the first pulse modulation converter Ml , which converts the phase-modulated pulses into code characters for the transmission of the signal. On the receiving side, the received code characters can be converted directly into amplitude-modulated pulses in the pulse modulation converter M 2 ', which then according to the exemplary embodiment according to FIG. 2 can be fed to the busbar after passing through the stretcher D.

For a better understanding of the time forks operating according to the resonance transfer principle, FIG. FIG. 4 shows a time diagram of the switches of the time fork on the side of central office A according to FIG. 1 specified. The individual diagrams are labeled s 1 ... s 5 according to the functions of the switches they represent. Each switch function is represented over time as a positive pulse series in which the relevant switch is open during the pulse pause and closed during the pulse duration. Each impulse in a series is also consecutively designated with Arabic numerals 1 to 6 or 7.

net, which indicate which channel or which amplitude-modulated pulse is currently being transmitted when a switch is closed. In the top diagram, assigned to switch group s 11, s 12 ... s In and switch s 2 , the Arabic numerals within the pulses also provide information about which of the switches in the switch group, each of which is assigned to a channel the switch s 2 is closed at the same time.

As the F i g. 4 shows, the capacitor Co according to FIG. 1 is used to transmit an amplitude-modulated signal pulse belonging to one of the channels 1 ... η from the relevant storage unit Sp 1 ... Memory associated with the output-side switch s5 charged. After this switch has opened again, the switch s2 and at the same time the switch of the switch group si belonging to the relevant channel closes, the charge stored in the capacitor Co being transferred to the relevant channel and at the same time a signal pulse in the opposite direction via the busbar Ls and the switch s 2 is stored in the capacitor Co. After the switch s 2 and the mentioned channel switch of the switch group s 1 have been opened, the signal pulse stored for the opposite direction in the capacitor Co is now fed to the modulation converter circuit MWS on the transmitter side by closing the switch s 4. Any remaining charge in the capacitor Co is eliminated after the switch s4 has been opened by briefly closing the switch s3. This game of switches is then repeated in the rhythm of the channel repetition frequency for channel 2, 3 ... n, which in turn is followed by channel 1.

The processes on the part of switching office B proceed accordingly. The synchronization between the control clocks for the switches in the various offices does not present any difficulties because, at least with regard to the phase, no synchronism is required by the buffer. The clock of an office extends to the input-side switches s6V, s62 '... s6n' or 56I, s62 ... s6n on the receiving side of the time division multiplex system of the respective remote office.

In known electronic switching offices that work with time bundling, the individual Channels with a period of about 100 usec each scanned for 1 μεεϋ. Considering an intermediate time between two samples to prevent crosstalk, About 50 connections, each of which is allocated a separate phase, can be connected via a time division multiplex busbar be guided. When connecting the busbars, two spatially separated ones Offices according to a circuit according to FIG. 1 it is difficult to find the 50 connections in the specified rhythm and the required high crosstalk attenuation over the To run time forks because they have a total of four switching cycles in the available time interval need to run one after the other. In this case, as has already been indicated, it is appropriate to the time division multiplex system consisting of two or more channel groups with group-wise modulation and demodulation to build up its individual groups, their channels for transmission in turn to one all groups comprising pulse frames are put together, each with its own timing fork connected to the time division multiplex busbars. With 50 busbar connections it should be sufficient if the time division multiplex system has two groups of 25 channels each, which are mutually combined in such a way for the transmission to a pulse frame that the timing forks of the two groups to transmit only every second of the successive channels to need.

Claims (12)

Patent claims: 1. Message system, in particular telephone system, consisting of central facilities for a large number of terminals connected therewith via individual channels, in which the optional connection of the terminals is made by time-division multiplex busbars in the central facilities assigned to them, characterized in that the switching between the terminals, which are assigned to different central facilities (A, B) , by time division multiplex systems with a suitable modulation for the transmission of the signals via cables, which are carried out between the time division multiplex busbars (Ls, Ls') of the relevant central facilities via the rhythm the channel repetition frequency operated switching devices are connected, and that intermediate storage devices are arranged in the connection path from the output of the time division multiplex systems on the receiving side to the time division multiplex busbars, the storage units (Sp 1 ... Spη or SpV ... Spn ') on the input and output side via switches operated one after the other in the rhythm of the channel repetition frequency (s61 ... s6n, s51 ... s5rc or s61'. . . s6n ', s 51' ... s 5n ') are parallel to each other. 2. System according to claim 1, characterized in that the time division multiplex systems with pulse phase modulation work. 3. System according to claim 2, characterized in that the time division multiplex systems in the transmission direction one after the other on the transmitting side a presser (F), one of the amplitude-modulated pulses Pulse modulation converter (Ml) converting into phase-modulated pulses and on the receiving side one that converts the phase-modulated pulses back into amplitude-modulated pulses Pulse modulation converter (Ml ') and a stretcher (D) . 4. System according to claim 1, characterized in that the time division multiplex systems with pulse code modulation work. 5. System according to claim 4, characterized in that the time division multiplex systems in the transmission direction one after the other on the transmitting side a presser (F), one of the amplitude-modulated pulses in phase modulated ^ pulses converting first pulse modulation converter (Ml), a die second pulse modulation converter (M 2) converting phase-modulated pulses into code characters and at the receiving end one that converts the code characters back into amplitude-modulated pulses Pulse modulation converter {M2 ') and a stretcher (D) . 6. System according to one of the preceding claims, characterized in that the output-side switches (s51 ... s5n or sSV ... s Sn ') of the storage units (Sp 1 ... Sp η or SpI' .. .Spn ') the buffer are included in the switching devices. 7. System according to any one of the preceding claims, wherein between the terminals and the time division multiplex busbars of the central facilities assigned to them two-wire connections are provided, characterized in that the switching devices hybrid circuits (Time forks) are. 8. System according to claim 6 or 7, characterized in that the switching devices according to are switches or timing forks that work according to the resonance transfer principle. 9. System according to claim 7 or 8, characterized in that the timing forks are T-members, in which the cross member consists of the series connection of an inductance (Lo or Lo ') with a capacitance (Co or Co') , the one the removal of the residual charge of the capacity after a completed charge exchange serving first switch (s 3 or s3 ') is parallel, and in which the busbar-side series branch is a second switch (52 or si') , while the series branch on the side of the time division multiplex systems in a transmitting and a receiving-side fork arm is split, of which the transmitting-side fork arm consists of a third switch (s4 or s4 ') , and the receiving-side fork arm of the mutually parallel output-side switches (sSl ... sSn or s51'. ..s5n ') of the storage units (SpI .. .Sp η or SpI' ... Sp n ') the intermediate storage is formed. 10. System according to any one of the preceding claims, characterized in that between two time division multiplex busbars from different central facilities composing two and more channel groups with group-wise modulation and demodulation Time division multiplex system is provided, its individual groups, their channels for transmission are in turn combined to form a pulse frame comprising all groups, each via its own switching device the time division busbars are connected, and that the switching devices for the individual channel groups in the specified order of the channel groups in the pulse frame one after the other are operated in the rhythm of the channel repetition frequency. 11. System according to any one of the preceding claims, characterized in that the Storage units of the intermediate storage capacitors are. 12. System according to one of claims 1 to 10, characterized in that the storage units the buffer are low-pass? i elements. 1 sheet of drawings 709 689/171 11. 67 © Bundesdruckeiei Berlin