LU79894A1 - MESSAGE TRANSFER SYSTEM - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT Our mark

Berlin and Munich VPA 77 P 6659 i

Foreign version

Message transfer svstea

The invention relates to a message transmission system for wired and / or wireless transmission of speech, music, text, images or data, containing the conventional Femmeldenetz for analog and possibly also 5 digital transmission with end and transit (analog network) ♦

The current telecommunications network of the Deutsche Bundespost and other postal administrations essentially consists of remote communication channels 10 with a bandwidth of 3.1 kHz each. A few digital transmission links are also inserted, via which 3 »1 kHz signals are transmitted at 64 kbit / s each.

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In the "Nachrichtenentechnische Zeitschrift", 29 (1976) Issue 3, 15 pages 190 to 210, a number of useful communication options such as office telex, facsimile, interrogation single image or electronic letter transmission are dealt with. are too slow when using today's analog telecommunications network or have to be rejected as uneconomical due to excessive tape requirements.

The pulse code modulation transmission devices which are present in part in the current telecommunications network and which transmit a 64 kbit / s signal per voice channel would be suitable per se

Wke 1 Bri / 5.5.1978 i -2- VPA 77 P 6659 to largely eliminate the disadvantages mentioned. To do this, however, the individual subscriber would have to be connected directly to the 64 kbit / s network, and the 64 kbit / s signal would have to reach the corresponding subscriber without interruption by any digital-analog and analog-digital conversions A four-wire or quasi-four-wire connection of the subscribers would also be necessary in order to be able to take full advantage of this connection. Since digital connections will only be available as intermediate sections within the analog network for the foreseeable future, 10 their advantages cannot be exploited.

* The object of the invention is to serve a subscriber group with a particular interest in digital transmission, which is to be sought in particular in the business world, if the predominantly analog network continues to exist. Among other things, the invention is intended to enable, for example, fast fax transmission, electronic mail, extended screen image services and high-quality encryption, and to bring improved voice quality.

20 Starting from a message transmission system of the type described in the introduction, this object is achieved according to the invention in that a network superimposed on the analog network is provided for purely digital transmission with its own transit exchanges (digital long-distance network) and in that digital end exchanges 25 are provided, which on the one hand are directly connected with analog-digital - or digital-to-analog converters having digital subscriber stations and, on the other hand, for each connection to be set up that goes beyond the end switching area, either with the digital long-distance network directly or with the analogue network via analog-to-digital 30 or digital-to-analog converter or at Connection to a section-wise digital transmission are connected via a code converter.

For the practical implementation of the subject matter of the invention, it is advantageous if digital end exchanges are provided which, based on a dialing code, transmit the signals coming from the digital subscriber stations either into the analogue network or into the digital network.

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It is also advantageous if the digital end exchanges are connected to their digital subscriber stations via subscriber lines with four-wire properties, which can be realized by time forks, hybrid circuits and / or crossovers. 5

It is advantageous if a delta modulator is provided for the analog-digital conversion of the speech in the subscriber station.

10 A message transmission system is already known from the magazine ttAIEE, Part 1, Communications and Electronics1 *, May 1957, pages 142 to 147, in which delta modulation is used from subscriber to subscriber, but this is one purely digital and not a hybrid network.

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It is also advantageous if additional identifiers are transmitted on the subscriber line by modulation or additional coding or by multiplexing.

It is also advantageous if part or all of the bit stream available for voice transmission is used continuously or temporarily for data transmission and / or signaling purposes.

25 It is also advantageous if encryptors and decryptors are provided in the digital network, in the digital end exchanges or in the digital subscriber stations for the purpose of secrecy, 30 It is also advantageous if a switch is provided, with which the full bit flow of a connection for voice terminals can be switched to a connection for data terminals and vice versa. A preamble can be used to control the switch. Different preambles serve to differentiate between different types of data signals.

It is also advantageous if a switch is provided which \

Cf - 4 - VPA 77 P 6659 activates data transmission manually or automatically during the natural pauses in speech.

The automatic switchover to data transmission can be controlled, for example, by voice signal recognition circuits, such as have been used in the TASI devices of the submarine cable systems for years.

It is also advantageous if memories are provided for services with smaller bit-10 rates, which are read out burst-like at the higher bit rate of the digital network, for example in the pauses in speech.

Finally, it is advantageous if a microprocessor is provided for memory control, multiplexing, code conversion, preamble evaluation, speech pause detection and / or monitoring.

The invention is explained in more detail below on the basis of exemplary embodiments.

20th

Show it: -

1 shows a message transmission system according to the invention,

2 shows two digital subscriber stations with their communication options, 25 FIG. 3 shows a digital end switch with two digital subscriber stations,

4 a digital subscriber station,

5 shows a transmission between two digital subscriber stations and FIG. 6 shows a data adapter for a digital subscriber station.

1 shows a basic circuit diagram of the message transmission system according to the invention. This contains the conventional analog network I, a digital network II, two end switching areas 1 35 or 1 ’and 3 or 3’> in which subscriber stations are located, and a long-distance network and transit switching area 2 or 2 ’. The square boxes without a dash represent switches - 5 - VPA 77 P 6659 gen Teleph.Ex. If the box contains an A, it is an analog switch, if the box contains a D, it is a digital switch . The telephones and the circles represent subscriber stations. If they are 5 marked with an A, they are analog subscriber stations, if they contain a D, they are digital subscriber stations. Such subscriber stations contain a commercially available analog-digital converter and a commercially available digital-analog converter for the voice signal.

10th

In the analog network I, a connection can be established in a conventional manner, for example between a subscriber station 4, which is connected to the analog terminal exchange 6, and a subscriber station 5, which is connected to the analog terminal exchange 7. In this pall, the message exchange takes place only in the analog network I via the corresponding analog switches A and the analog femnet 2.

The same is possible in the digital network II between a subscriber station 8, 20, which is connected to the digital terminal exchange 9, and a subscriber station 13 ', which is connected to the digital terminal exchange 11. For a connection between the digital subscriber stations 8 and 13, depending on the dialing code, the connection is made either via the digital end switch 9, the digital 25 telephone network 2 'and the digital end switch 11 or via the digital end switch 9, a commercially available digital

Analog converter 10, the analog network I, a commercially available analog-digital converter 12 and the digital end switch 11 are manufactured. If the analog network I is not suitable for the desired communication, then only transmission via the digital femnet 2 is possible.

If a connection is to be established from the digital subscriber station 8 to the analog subscriber station 5, this is set up via the digital terminal exchange 9, via the digital-to-analog converter 10 and the analog network I.

Conversely, if a connection is to be established from the analog subscriber station 5 to the digital subscriber station 8, this is forced without any special dialing code via the analog network I to the last analog switch, the end switch. lung 6, and from there built on the analog-to-digital converter 10 and 5 via the digital end switch 9.

The possibilities presented by the message transmission system according to the invention are demonstrated on the basis of FIG. It shows schematically the digital subscriber stations 8 and 13 according to Fig.1. 10 In the digital subscriber station 8, a switch 19 can optionally be used to connect a telephone 19, for example with hands-free options, an office teleprinter 14, a screen device 15, for example for screen text or still images, or a facsimile device 16 to the transmission line. The digital subscriber station 13 contains corresponding devices, the reference numerals of which are provided with an apostrophe to distinguish them. Optionally, an encryption device 18, 18 'can be inserted, which contains an exclusive OR gate 181 181 * for modulo-2 addition and a commercially available pseudo-random generator 182, 182' 20, which consists, for example, of a feedback shift register.

With 64 kbit / s delta modulation, the entire speech spectrum can be transmitted without restriction 25 from the telephone 19 to the telephone 19 ’. Compared to the band-limited transmission w in the CCITT voice channel (300 Hz to 3400 Hz), this means a significant improvement in voice quality and an increase in intelligibility, especially in foreign languages.

30 Delta modulation is better adapted to the speech spectrum than pulse code modulation, so that even with the greatly expanded low-frequency band, very little quantization distortion occurs. Because of the high sampling frequency, the low and low-pass filters necessary for pulse code modulation can be omitted. Furthermore, a delta codec is much simpler and therefore cheaper than a pulse code modulation codec. The four-wire connection to the subscriber enables real hands-free talking. Echo locks can be omitted. In addition, there are no attenuation fluctuations with digital transmission.

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Conference calls are possible. Priority subscriber stations can be implemented using the digital connection for switching without additional lines. Due to the greater bandwidth of delta modulation compared to PCM, the quality of a home receiver can be achieved with music transmission. This enables new services such as "Dial a Hit" (hit of the week over the phone).

Very fast data transmission is possible between office teleprinters 14 and 14 ’(1 DIN A 4 page in approx. 0.3 s).

Fast data communication between monitors and computers is also possible.

15 With monitors 15 and 15 'it is possible to transfer still images with accompanying text. The transfer of a screen image with 625 line resolution in color takes about 25 s.

There is a between facsimile devices 16 and 16 ’. Fast remote copying possible. Approx. 15 s are required to transfer a DIN A-4 page with a resolution of 8 lines / mm. The redundancy reduction required in the current fast facsimile transmission in voice channels can be eliminated, which saves effort and reduces the sensitivity to transmission interference. In addition, the expensive 4.8 kbit / s modems, some of which work with adaptive equalization, are saved.

Telephoning and remote copying can also optionally take place simultaneously if 32 kbit / s are assigned, the 30 speech quality is still good and a DIN A-4 page in approx.

30 s is transferable.

The possibility of using fast and inexpensive femcopier devices is regarded as a significant advantage of the message transmission system according to the invention. Accompanying material for a long distance call in picture or written form can be immediately delivered with ¥ * - 8 - VPA 77 P 6659. The area's in-house mail is already relieved in the first stage of expansion of an extension network.

3 shows in detail the digital end-5 switch 9 shown in FIG. 1 with two digital subscriber stations 8 'and 8 ".

One connection serves as an output in the digital remote network 2 *, another connection serves as an output in the analog network I. Since in this example two-wire lines were accepted as connections in the analog 10 network I and in the digital long-distance network 2 *, a four-wire connection must be made Fork circuits are provided. A circuit 27 with a digital fork 271 and a line transmission 272 is therefore provided in the output to the digital remote network 2. At the output of the analog network there is a circuit 20 15 with a commercially available codec 201, 202 and with an analog fork 203. Furthermore, a clock supply 21 and an audible signal generator 22 are provided, which consist, for example, of an analog-digital converter 221, a scanner 222 and a tone generator 223 exists. The subscriber station 8 'and 8 "contain digital adapters 231 20 and 23", as explained in more detail in FIG. 4 under the reference symbol 231, telephones 25' and 25 ", data device adapters 24 'and 24", as shown in FIG .6 are explained in more detail under reference numerals 39 and 40 and data devices 26 'and 26 ".

FIG. 4 shows a digital subscriber station 8 * according to FIG. 3 in detail. The digital adapter 23 'contains a commercially available voice signal codec 34, a switchover device for voice / data 28, which in principle corresponds to the switch 17 in FIG. 2 and is explained in more detail in FIG. 6 under the reference symbol 45 and an arrangement 29 with 30 a demultiplexer 291 and with a multiplexer 292 in the form of a switch with a digital fork 292 and with a line, transmission 292 for two-way duplex transmission. The telephone 25 contains a receiver 30, a microphone 31, a call sign receiver 32 and a dialing signal generator 35. Furthermore, the data device adapter 24 'and the data device 26' are shown again.

5 shows the voice and fast data transmission between two digital subscriber stations 8 and 13 according to FIG. 1 with elements of the digital subscriber stations according to FIG. 4. In the digital subscriber stations 40 there is still a first commercially available data storage - 9 - VPA 77 P 6659 cher 37 hzw. 37 *, a second commercially available data memory 35 or 35 ', such as a RAM (random access memory) and a commercially available data printer 36 or 36'.

5 The switching device 28 or 28 * contained in FIG. 5 has the task of enabling different services to exchange signals via the 64 kbit / s transmission. In the case of pure voice transmission, the corresponding position of the switch 28 or 28 'ensures that the microphone 31 of the codec 34 and the transmission connection are connected to the codec 34 * and the receiver 30'. The opposite direction is switched accordingly (311-34’-34-30).

If only data is to be transmitted, the switch 28 ~ or 28 'is flipped. The 64 kbit / s transmission is then each connected to 15 the data memories 37 »35 or 37 *> 35 '. The data storage was provided here in order to enable slow data sources and data sinks via the 64 kbit / s to optimally exchange data. Such slow data sources or data sinks could, for example, be office teleprinters, as they were designated in FIG. 2 with 14 20 or 14 '.

However, data bursts can also be transmitted during pauses in a conversation. This is possible since information generally only has to be transmitted 25 in one direction of conversation. This allows data to be transmitted in the opposite direction, w This was assumed in the position of the switches 28 and 28 'shown in FIG.

When the switches 28 and 28 'are shown, signals are transmitted from the microphone 31 via the modulator of the speech signal codec 34,' the switch 28, the transmission line, the switch 28 'and the demodulator of the speech signal codec 34' to the listener 30 '. At the same time, data is transmitted from the data store 37 ’via the transmission line to the data store 35 and the data printer 36. When the switches 28 and 281 are flipped, the transfer takes place in the opposite direction.

6 shows a combination of the data adapter 24 'of FIG. 4 with - 10 - VPA 77 P 6659 of the switching device 45, which in principle corresponds to the switch 28 or 28' of FIG. 5, in one embodiment without using a microprocessor. The circuit includes a data end part 39 and a data reception part 40.

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The most important part of the data transmission part 39 contains a commercially available transmission memory 41, in which the data can be read in at the usually slow speed inherent in the data terminal 38 and can be kept ready for transmission at 64 kbit / s 10. For transmission by hand or automatically in the

Pauses can be initiated, the transmit memory 41 is switched to the line instead of the speech signal codec 34 and then a preamble of a commercially available preamble generator 42 is read out with the switch 45b.

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In the receiving part 40, a commercially available preamble decoder 43 recognizes the beginning of the data burst and switches from the speech signal codec 34 to a commercially available data reception memory 44 for a short time, for example until the memory 44 is full.

Subsequently, the data terminal 37 connected on the receiving side can read the receiving memory 44 at its own data speed.

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Claims (15)

1 V% «-12- VPA 77 P 6659 1. Message transmission system for wired and / or wireless transmission of speech, music, text, images or data, containing the conventional Ferameldenetz for analog and possibly also section by section digital transmission with end and transit exchanges (analog network), characterized in that the analog network (I) superimposed additional network (2 *) is provided for purely digital transmission with own through exchanges (digital long-distance network) and that digital end exchanges (9, 11) are provided, which on the one hand directly with analog-digital * or. Digital V-analog converters with digital subscriber stations (8, 13th and, on the other hand, for each connection to be set up that goes beyond the end switching area, either with the digital femnet (2 ·) directly or with the analogue network (I) via analog-digital or digital-to-analog converter (10, 12) or when connected to a section-wise digital transmission via a code converter (FIG. 1). 2. System according to claim 1, characterized in that digital end exchanges (9, 11) are provided which, based on a dialing code, the signals coming from the digital subscriber stations (8, 13) either in the analog network (i) or in convey the digital long-distance network (2 '). 3. System according to claim 2, characterized in that the digital end exchanges (9, 11) with their digital subscriber stations (8, 13) are connected via subscriber lines with four-wire properties. 4. System according to claim 3> characterized in that the four-wire properties are realized by time forks. 5. System according to claim 3, characterized in that the four-wire properties are realized by hybrid circuits and / or crossovers. 6. System according to claim 1, characterized in that a delta modulator is provided for an analog-digital conversion of speech in the subscriber station. 7. System according to any one of the preceding claims, characterized in that additional identifiers are transmitted on the subscriber line by modulation or additional coding or by multiplexing, 8. System according to one of the preceding claims, characterized in that part or all of the bit stream available for speech transmission is used continuously or temporarily for data transmission and / or signaling purposes. 9. System according to any one of the preceding claims, characterized in that in the digital network (II), in the digital end exchanges (9, 11) or in the digital subscriber stations (8, 13) for the purpose of secrecy encryptors and decryptors (18, 18 ' ) are provided. 10. System according to any one of the preceding claims, characterized in that a switch (17, 17 *) is provided with which the full bit flow can be switched from a connection for voice terminals to a connection for data terminals and vice versa. 11. System according to claim 10, characterized in that a device for generating a switch (17, 17 ') controlling preamble is provided as a label. 12. System according to claim 11, characterized in that a device for generating different preambles for distinguishing between different types of data signals is provided, 13. System according to any one of the preceding claims, characterized in that a switch is provided which a data ['! »Jv î 1 X -13- VPA 77 P 6659 Transmission switched on manually or automatically in the naturally available pauses. 14. System according to one of the preceding claims, characterized in that memories are provided for services with lower bit rates, which are read out burst-like with the higher bit rate of the digital network, for example in the pauses in speech. 15. System according to any one of the preceding claims, characterized in that a microprocessor for memory control, multiplexing, code conversion, preamble evaluation, 'speech pause detection and / or monitoring is provided. "i