CH627556A5 - Digital transmission system, particularly for PCM signals, comprising an alphabet code converter - Google Patents

Description

The invention relates to a digital transmission line terminal to transmit.

plant, in particular for PCM signals, with one between two according to the invention the object is achieved in that

End stations and regenerating amplifier stations for the use of an address-free error location method containing transmission path and with at least one “the alphabet-code converter an additional control input alphabet-code converter, which contain binary signals each m bits long, which a normal logi during normal operation -in ternary signals with n trivalent signal elements each, assumes in the seen state and which is called for the transmission of location-following Tit, converts signals in the sending terminal into a second logical state, and converts back in the receiving terminal, where m that the transmitting alphabet Code converters are concerned with the and n natural numbers, and during the normal 50 second logical state its association between the operating binary signals corresponding to the intended code alphabets and the specified ternary output signals with a certain maximum n changes the number of signals in such a way that they are generated during the norma nulltit. maximum possible number of zero tits

Alphabet-code converters are used to convert digits that when recording binary signals with g blocks of tale signals, in particular of ternary signals with g blocks of PCM signals present in a binary code with m zero bits each on the output side in an alphabet code and to be recognized with n ternary null tits that the corresponding reverse conversion. From the proceedings of the alphabet-code converter on the interfering side when the second national Zurich seminar on digital communications from the 12th - logical state was concerned, its assignment between the recorded 15.3.1974, lectures Fl and F2, known such alphabetical ternary signals and the emitted binary Signa codes are, for example, the 4B 3T code, the MS 43 code 60 len changes in such a way that when recording g blocks and the Fomot code. In these cases, code converters with n ternary zero-tits g blocks with m zero-bits are used, by means of which a binary signal, which is in blocks of m each, is 2m <3 "and that g is a natural number. Bit length is converted into a ternary signal. The main advantage of the invention is that for the location and every binary block with m bit by a ternary measurement measurement a test signal in the transmission code uses block with n tit (ternary digit) is replaced following code can be 65 and the test signal at the digital interface modified MS 43 code (MMS 43-Lock), the code of the transmission-side line terminal can be fed in and can also be evaluated by swapping the positions of individual binary values. This ensures that all parts with each other or by exchanging the ternary code alpha of the line terminal, in particular also the alphabet code

Converter to be checked. A special solution results from the fact that the transmitter-side alphabet code converter is provided for converting binary signals scrambled with a pseudo random sequence into ternary signals corresponding to a modified MS 43 code, and the input-side code converter is used for reverse conversion.

The invention will be explained in more detail below with reference to the drawing, for example. The drawing shows:

Fig. 1 shows the transmitting part of a line terminal of a PCM system to be monitored and

Fig. 2 shows the receiving part of this PCM system.

The transmitting part of a line terminal shown in FIG. 1 receives the signals to be transmitted via the first digital interface 1 .DS, which are present in HDB3 code in accordance with the regulations of the International Telecommunications Authority CCITT and have a bit rate of approximately 34 Mbit. The first decoder Deel, which is a known HDB3 decoder, connects to the digital interface 1 .DS. The decoded signals are then fed to a scrambler Seri, which contains a pseudo random generator and an exclusive-OR gate and in which the generated pseudo random sequence is fed to one input of the exclusive-OR gate and the decoded signals are fed to the other input and to one another modulo-2 can be added. This results in a scrambling of the signals to be transmitted, by means of which bit sequences which are difficult for transmission, for example long sequences of zero bits or one bits, can be eliminated. This ensures synchronization during the transmission of all signal sequences in all parts of the PCM system, in particular also in the alphabet converter. The output signals of the scrambler Seri are fed to the first alphabet code converter ACW1, which converts them into the MMS 43 code, which is particularly favorable for transmission via coaxial cables at high bit rates, and outputs the converted signals to the first line interface 1 .LS for further transmission.

3,627,556

The first alphabet code converter ACW1 is connected via an additional control line to a switch S1 and a bias voltage source U1, by which a part connected in parallel with the normal alphabet code converter is only periodically switched on during the transmission of the loop closure signal and the normal alphabet Code converter can be turned off at the same time. This additional code converter part is used for code conversion of the loop closure signal consisting of binary zeros into one which consists of ternary null oils and in which the assignment between binary signal and ternary signal no longer corresponds to the alphabet code MMS 43. In the present case, the location command in the binary form consists of three groups of four zero bits each, which are represented in the ternary form by three groups with three ternary 15 zero bits each.

A second switch S2 is coupled to the switch S1 for switching over the first alphabet code converter ACW1 on the transmission side, which switches over the switchover of the receiving part shown in FIG. 2. The receiving part is constructed analogously to the 20 transmitting part, it receives the signals transmitted on the second line interface 2LS and present in the MMS 43 code, which are converted back into binary form in the second alphabet code converter ACW2 connected to the second line interface. After the conversion 25, the signals are fed to a scrambler Scr2, which, by renewed modulo-2 addition with the pseudo-random sequence in the transmitting section in the receiving section, restores the original binary signal, which is cod 2 in the connected HDB3 encoder converted into the desired interface code 30 and delivered to the second digital interface 2.Ds. A bias voltage source is also coupled to the second switch S2, which periodically activates a second code converter part in the code converter ACW2 and switches off the actual code converter at the same time, so that the desired conversion of the loop closure signal which is outside the regulations of the MMS 43 code takes place in the location 35 .

C.

1 sheet of drawings

Claims (2)

627 556 2 PATENT CLAIMS pray in the order they appear. In these cases 1. A digital transmission system, in particular for PCM series for code conversion for a given sequence of m bit signals, with one and more sequences from n Tit located between two end stations, with the transmission generating amplifier stations containing the assignment specified rules are carried out which relate to the digital sum accumulated at the end of the stretch and with at least one alphabet code converter, the 5 preceding blocks n tit, binary signals with m bits in length into ternary signals with n. Through the use of alphabet-code converters in di-trivalent signal elements, hereinafter referred to as tit, in the gital transmission systems, it is therefore possible to convert the moving terminal and to convert the quantity of information back into the receiving end at a reduced speed, whereby m and n are natural numbers. If the requirement that 2m <3 "is met and that is the intended Coio during normal operation, the ternary output signal does not contain all the output signals corresponding to the possible de-alphabets with a combination of ternary elements. In the case of digital transmission systems, in particular in the case of sol, that the use of an address-free error for PCM signals, it is customary for the individual intermediate location methods to use the alphabet code converters (ACW1 , 2) part of a transmission line and possibly also the line end genes contain an additional control input, which assumes a first logical state during loop formation between the two signal signaling operations and leading wires of the transmission line and transmission of the signals for the transmission of location signals a second logi of test signals is switched over to the bargaining state via the loop closures that are formed, to check that the transmitter-side alpha. These test or location signals contain bet code converters (ACW1), when the second logical signal is present, as a loop closure signal, a periodic portion, the state of its association between the signals received from the regenerator in the direction of location of an intermediate point and the ternary signals emitted Signals in the is known and this changes to form loops in the other way that the regenerator possible during normal operation causes the same intermediate point. The maximum number of null tits is exceeded, that when these location signals are transmitted in transmission systems, binary signals with g blocks with m zero bits each have alphabet code converters in their line terminals on the output side contain ternary signals with g blocks with n ternary 25th, is not easily possible. On the one hand, this is due to the fact that nulltits are given that the alphabet on the receiving end - that according to the above-described mode of operation code converter (ACW) when the second logical addition is applied - the alphabet-code converter has a binary input signal at the point of its assignment between the recorded terna - Output of the code converter, depending on the starting conditions, leads to ren signals and the emitted binary signals in the way of different ternary signal sequences and thereby changes one that when g blocks with n ternary 30 loop closure signals occurring periodically in the locating signal come with zero tits g blocks m zero bits are output that 2m <3 "would be converted into several different signals. Ande-ist and that g is a natural number. On the other hand, it is 2. Transmission system according to claim 1, characterized expediently as a periodic loop closure signal that indicates that the transmitter-side alphabet code converter is to be used in the location signal that is used in (ACW 1) to convert binary, with a pseudo-random alphabet Code are not provided. Such a signal sequence follows scrambled signals in ternary, a modified MS is a sequence with more than n zero steps in the secondary signal. 43-code corresponding signals and the receiving-side code. The object of the invention is therefore to provide for a converter (ACW2) for reverse conversion. Transmission system of the type described at the outset is able to locate faults by forming loop closures. 40 den; In particular, the task consists in the loop closure signal consisting of several digital zeros within the