RU2099884C1 - Method of duplex transmission of digital information over two-wire circuit and device for its realization - Google Patents

Abstract

FIELD: electric communication, applicable for organization of duplex communication of a party or group of parties with an automatic telephone exchange over a two-wire circuit, with provision of main access to the digital circuit. SUBSTANCE: at a transmission of signal from party 1 towards automatic telephone exchange 5 the signal is converter to a three-level bipolar sequence by means of converter 2 realizing a transition from a random binary signal to a bipolar one, in which alternation of polarity of unit amplitude pulses occurs. At a transmission of signal from electronic automatic telephone exchange 5 towards party 1 the signal is converter to a multi-level sequence by means of converter 6 realizing a transition from a random binary signal to an absolute bipulse sequence with predistortion of pulse amplitudes. EFFECT: simplified device realizing the method of duplex transmission of digital information over a two-wire circuit, expanded abilities of application of this method. 2 cl, 17 dwg

Description

 The invention relates to the field of telecommunications and can be used for organizing duplex communication of a subscriber or group of subscribers with an automatic telephone exchange through a two-wire circuit, including the implementation of basic access to a digital network.

 A known method [1] of duplex transmission of digital information on a two-wire circuit, in which the separation of transmission directions by decoupling by attenuation is carried out using differential systems and digital echo cancellers. At the same time, subscribers of electronic telephone exchanges at their request can be provided with the so-called basic access to a digital network with the integration of services.

 In accordance with the recommendations of the CCITT in 1984 [2], the basic access subscriber kit can contain up to eight different devices, including digital telephones, telefax, teletex and video tex, personal computers, etc. Each of of the above devices has access to two switched channels with a speed of 64 kbit / s and one additional channel with a speed of 16 kbit / s, with the help of which all signals related to call processing are received and sent. The same additional channel is used to transmit and receive low-speed signals by packet switching.

 All these devices are output to common four-wire buses, on which a frame is organized in which digital signals are transmitted at a speed of 192 kbit / s. In the consumer’s premises, this frame at junction S is processed into another frame at a speed of 160 kbit / s. This frame is broadcast on one telephone pair to station V, with the organization of signal transmission in both directions simultaneously using digital echo cancellers. The equipment of this type, providing simultaneous transmission of digital signals at a speed of 160 kbit / s in both directions using digital echo cancellers, which is produced by a number of well-known companies [1] is very complex. Its effectiveness is ensured by the use of ultra-large integrated circuits, the production of which is quite difficult, as a result of which the cost of the devices is relatively high.

The closest in technical essence to the proposed one is the Erickson company equipment [3] containing digital echo cancellers and differential systems included between the subscriber set and the electronic telephone exchange, with the help of which the digital streams transmitted in a duplex way via a two-wire subscriber line are separated (Fig. 1). Moreover, to select a digital signal using an adaptive filter, a balanced signal is generated, which avoids the influence of reflections on the reception quality. The reflected signal Y _{k is} recorded in the form of a pulse sequence with a deterministic clock interval set when transmitting the outgoing signal X _k . The compensating signal Z _{k is} generated in such a way as to most fully ensure that the equality Z _k -Y _{k is} fulfilled, which allows achieving good results in suppressing the reflected signal and restoring the received sequence.

 The main disadvantage of this method is the complexity of the device that implements it, which is caused by the design features of digital echo cancellers.

 In addition, this method has a limited scope, because does not allow the use of composite cable pairs without reducing the quality of the transmission in the presence of significant heterogeneities at the junction of pairs of various types; apply digital subscriber lines with high attenuation (more than 40 dB at a frequency of 80 kHz) due to the limited accuracy of compensation of reflected signals; use a large number of systems on different pairs in one cable while limiting the transient influences acceptable for a given cable at the near end due to level differences of up to 40 dB during oncoming transmission of information; organize wired broadcasting of the highest class using subscriber communication lines, as Such a digital broadcast channel requires a transmission rate of more than 144 kbps.

 The purpose of the invention is the simplification of a device that implements a method of duplex transmission of digital information on a two-wire circuit, as well as expanding the possible field of application of this method.

This goal is achieved by the fact that there is a method of duplex transmission of digital information on a two-wire circuit, which consists in the simultaneous transmission of digital signals from an electronic telephone exchange to the subscriber and from the subscriber to the electronic telephone exchange between the connecting points S and V with their subsequent separation, they convert the binary signals of the subscribers into bipolar a sequence occupying a frequency band of 0 ^o C ω ₁ binary signals of an electronic telephone exchange in an absolute bi-pulse sequence with a 2-fold decrease in the amplitudes of one after another ohms of pulses of the same polarity, occupying the frequency band (ω ₂ > ω ₁ ) ω ₁ ÷ ω ₂ , then independently transmit signals of two directions with their subsequent frequency separation and reverse conversion to the original binary digital signals, while the pulse duration of the bipolar sequence should be 4 times the pulse duration of the absolute bi-pulse sequence.

при α 1 для биполярного сигнала, длительность импульсов которого равна длительности тактового интервала, и

для многоуровневых сигналов другого типа, длительность импульсов которого также равна длительности тактового интервала, где ω $\genfrac{}{}{0ex}{}{\text{бип}}{\text{1}}$ и ω $\genfrac{}{}{0ex}{}{\text{мн.с.}}{\text{1}}$ верхние границы частотного диапазона, занимаемого соответственно биполярным сигналом и многоуровневым сигналом другого типа

.As a multi-level signal occupying the frequency band 0 ^o C ω ₁ ÷ ω ₂ can be used, in particular, signals bipolar [4] duobinary, NWZT, NDVZ, etc. [5] To accommodate the energy spectra of these signals and the absolute bi-pulse sequence with a 2-fold decrease in the amplitudes of successive pulses in the conjugate frequency ranges, respectively, ω ₁ and ω ₁ ÷ ω ₂ (figure 2), which ensures the separation of the two transmission directions with using HF filters for direction "station-subscriber" and LF filters for direction "subscriber station", it is necessary that the ratio of pulse duration τ absolute biimpulsnoy sequence _ab.k pulse duration much rovnevyh signals τ _mn.s. was

when α 1 for a bipolar signal, the pulse duration of which is equal to the duration of the clock interval, and

for multilevel signals of another type, the pulse duration of which is also equal to the duration of the clock interval, where ω $\genfrac{}{}{0ex}{}{\text{beep}}{\text{one}}$ and ω $\genfrac{}{}{0ex}{}{\text{plural}}{\text{one}}$ upper limits of the frequency range occupied respectively by a bipolar signal and a multilevel signal of another type

.

For further consideration, a bipolar signal will be used as a multilevel signal occupying the frequency range 0 ^o C ω ₁ , for which α 1 and pulse duration t _beep should be 4 times the pulse duration τ _{ab of} an absolute bi-pulse sequence.

 It is significant that for the placement of two different transmission directions in non-overlapping frequency ranges, modulation methods using carrier frequencies [6] are not used, the implementation of which greatly complicates and increases the cost of devices installed on the telephone exchange and in the consumer’s premises, as well as reduces noise immunity and therefore, reduces transmission quality.

 This goal is also achieved by the fact that in the device designed to implement the specified method, between the subscriber complex and the electronic telephone exchange connected by the subscriber line, serial-connected binary signal to bipolar sequence converter, the input of which is connected to the subscriber output, is introduced in the direction "subscriber-station" kit, low-pass filter and converter of the bipolar sequence into a binary signal, the input of which is connected to the output of the electronic telephone exchange, and in the direction of “station- subscriber "- a serial converter of a binary signal into an absolute bi-pulse sequence with a predistortion of pulses, the input of which is connected to the output of the electronic telephone exchange, an RF filter and a converter of an absolute bi-pulse sequence with a predistortion of pulses into a binary signal, the output of which is connected to the input of a subscriber set, the binary to absolute bi-pulse converter with pulse pre-emphasis contains the first to fourth RS triggers, the first and second logical electronic ORs, the first to fifth delay lines, the first and second buffer amplifiers, the first and second sign-change detectors (each of which consists of a series-connected differential circuit, a drive, and a first threshold device), the first logic element is NOT, and the transformer, and the binary signal output The electronic telephone exchange is connected directly to the S-input of the first RS-flip-flop, directly to the S-inputs of the second and third RS-flip-flops through the first logic element, to the S-input of the fourth RS-flip-flop, through the first connected in series logic element NOT and a third delay line, the output of the electronic telephone exchange timing signal is connected to the R-inputs of the first and third RS-triggers through the fourth delay line, and with the R-inputs of the second and fourth RS-triggers through the fourth and fifth delay lines connected in series, the outputs the first and fourth RS-flip-flops are connected to the inputs of the first logical element OR, the outputs of the third and second RS-flip-flops are connected to the inputs of the second logical element OR, the outputs of the first and second logical elements "OR" are connected respectively cuts the first and second delay lines and the first and second buffer amplifiers connected in series to the corresponding transformer windings, as well as through the corresponding first and second sign-change detectors to the second inputs of the first and second buffer amplifiers, and the absolute bi-pulse sequence converter with pulse predistortion into a binary signal contains the second threshold device, half-wave and half-wave rectifiers, the first and second logical elements AND, the second logical element NOT and w there is a delay line, while the input of the second threshold device is the input of the converter, and the output is connected to the inputs of the half-wave and half-wave rectifiers, the output of the half-wave rectifier is connected to the input of the sixth delay line and the input of the second logic element NOT, the output of which is connected to the first input of the AND gate, the second input of which is connected to the output of a half-wave rectifier, and the output to the first input of the second logical element And, the second input of which is connected to the output of the sixth lines of delay, and the output is the output of the converter.

It is known to convert a binary digital signal into a bipolar sequence, which is performed to transmit digital information along the linear paths of long-distance communication systems and to avoid the presence of a constant component in the spectrum of the transmitted signal, as well as to obtain a low specific gravity of the LF and HF components of this spectrum and, accordingly, a low level of transition Interference on the channels of frequency-division systems operating on parallel pairs of a symmetrical cable [7]
However, the use of this sequence for duplex transmission requires, in contrast to the claimed solution, two cable pairs. This allows us to conclude that the proposed solution meets the criterion of "significant differences".

 Figure 3 shows a block diagram of the proposed duplex transmission of digital information on a two-wire circuit; 4 and 5 are diagrams of the individual blocks included in the device that implement the proposed method; 6-17 explain the proposed method and operation of the device that implements it.

 The block diagram (Fig. 3) shows: 1 subscriber, 2 converter of binary signals into a bipolar sequence, 3 low-pass filter, 4 - converter of a bipolar sequence into binary signals, 5 - electronic telephone exchange, 6 converter of binary signals into an absolute bi-pulse sequence with pulse predistortion, 7 high-pass filter, 8 - bi-pulse sequence converter with pulse predistortion into binary signals.

τ₁ ≅Т; τ₁ и Т соответственно длительность и период следования импульсов биполярного сигнала.In accordance with FIG. 3, when the signal is transmitted from the subscriber 1 to the side of the electronic telephone exchange 5, it is converted into a three-level bipolar sequence using a converter 2, which transfers from a random binary signal to a bipolar [4] in which, as shown in FIG. 6, the polarity of the pulses of unit amplitude is alternated. The energy spectrum of the bipolar sequence (Fig. 7) occupies the frequency range 0 ^o C ω ₁ which contains about 98% of the total signal power [9] Here

τ ₁ ≅Т; τ ₁ and T, respectively, the duration and repetition period of the bipolar signal pulses.

The above arrangement of the energy spectrum of the bipolar signal transmitted from subscriber 1 to the electronic exchange 5 determines the need to place the energy spectrum of the reverse direction signal in the frequency range bounded below by the frequency ω _1. For this purpose, when the signal is transmitted from the electronic exchange 5 to the side of subscriber 1, it is converted in a multi-level sequence using a converter 6, which transfers from a random binary signal to an absolute bi-pulse sequence minute pulse with amplitude predistortion [7] The principle of this conversion is illustrated by Figure 8.

Легко видеть, что в рассматриваемом случае для эффективного разделения частотных диапазонов прямого и обратного направлений необходимо уменьшить частоту ω₁ и увеличить частоту ω₂ что возможно осуществить путем уменьшения длительности импульса τ₂ при максимально возможной длительности τ₁ Т. Однако подобные операции привели бы к значительному расширению полосы частот, необходимых для передачи абсолютного биимпульсного сигнала (фиг.10). Избежать данного недостатка позволяет применение абсолютной биимпульсной последовательности с предыскажением амплитуд импульсов. Введение предыскажений амплитуд импульсов абсолютной биимпульсной последовательности, впервые описанное в [7] и осуществляемое в соответствии с фиг.11, предполагает уменьшение амплитуды двух следующих друг за другом импульсов одинаковой полярности в β раз по сравнению с амплитудой импульсов чередующейся полярности. Предыскажения описанного типа позволяют трансформировать энергетический спектр передаваемого сигнала таким образом, что достигается значительное уменьшение низкочастотных составляющих спектра, степень которого определяется величиной параметра b
На фиг.12 показан характер изменения энергетического спектра абсолютной биимпульсной последовательности в области низких частот с ростом коэффициента b. Фиг.12 свидетельствует о том, что при b 2-2,5 может быть достигнуто сокращение доли общей мощности сигнала, содержащейся в полосе частот 0 ^oC w_ср, до 1-3% где

Отсюда следует, что для совместной передачи сигналов прямого и обратного направлений с помощью предложенного способа необходимо разместить энергетический спектр биполярного сигнала в области частот 0

что позволит производить разделение направлений передачи с помощью НЧ- и ВЧ-фильтров с низким уровнем вносимых искажений.Fig. 8 gives an idea of an algorithm for converting a binary sequence to an absolute bi-pulse one, where each binary unit is transmitted using a pair of -1, +1. The energy spectrum of the obtained sequence, as shown in Fig.9, is located in the frequency range 0 ^o C ω ₂ where

It is easy to see that in the case under consideration, for the effective separation of the frequency ranges of the forward and reverse directions, it is necessary to reduce the frequency ω ₁ and increase the frequency ω _2, which can be done by reducing the pulse duration τ ₂ at the maximum possible duration τ ₁ T. However, such operations would lead to a significant expanding the frequency band necessary for transmitting an absolute bi-pulse signal (Fig. 10). The use of an absolute bi-pulse sequence with a pre-emphasis of pulse amplitudes allows one to avoid this drawback. The introduction of pre-emphasis of pulse amplitudes of an absolute bi-pulse sequence, first described in [7] and carried out in accordance with Fig. 11, implies a decrease in the amplitude of two successive pulses of the same polarity by a factor of β compared with the amplitude of pulses of alternating polarity. The predistortions of the described type make it possible to transform the energy spectrum of the transmitted signal in such a way that a significant reduction in the low-frequency components of the spectrum is achieved, the degree of which is determined by the value of parameter b
On Fig shows the nature of the change in the energy spectrum of the absolute bi-pulse sequence in the low frequency region with increasing coefficient b. 12 shows that when b 2-2.5 can be achieved by reducing the share of the total signal power contained in the frequency band 0 ^o C w _cf to 1-3% where

It follows that for the joint transmission of signals of the forward and reverse directions using the proposed method, it is necessary to place the energy spectrum of the bipolar signal in the frequency domain 0

which will allow the separation of transmission directions using low-pass and high-pass filters with a low level of introduced distortion.

. Данное ограничение может быть достигнуто в связи с тем, что введение предыскажений наряду с уменьшением низкочастотных составляющих спектра абсолютной биимпульсной последовательности предполагает аналогичное уменьшение высокочастотных составляющих указанного спектра. Степень уменьшения высокочастотных составляющих значительно превышает степень уменьшения составляющих в области низких частот, поскольку спектр одиночного прямоугольного импульсаS(ω), входящий в качестве сомножителя в выражение для энергетического спектра передаваемого сигнала, имеет вид, изображенный на фиг.14.For this purpose, it is sufficient to set τ ₂ T / 4 at τ ₁ T, which allows one to obtain the arrangement of frequency ranges shown in Fig. 13 for the signals of the forward and reverse directions. The resulting frequency band arrangement system provides, along with efficient separation of transmission directions with the help of simple low-pass and high-pass filters, an additional restriction of the transmitted frequency band of the absolute bi-pulse sequence with a frequency of ω ₂ ≈ 3ω _T , where

. This limitation can be achieved due to the fact that the introduction of pre-emphasis, along with a decrease in the low-frequency components of the spectrum of the absolute bi-pulse sequence, implies a similar decrease in the high-frequency components of the specified spectrum. The degree of reduction of the high-frequency components significantly exceeds the degree of reduction of the components in the low-frequency region, since the spectrum of a single rectangular pulse S (ω), which is included as a factor in the expression for the energy spectrum of the transmitted signal, has the form shown in Fig. 14.

 It follows from the above that the new principle of using the combination of the energy spectra of multilevel sequences known from [4] - [7] allows for the first time in world practice to carry out joint transmission of signals of direct and reverse directions through two-wire communication lines without the use of expensive and complicated echo cancellers and differential systems, as well as without ineffective in this case, frequency modulation techniques.

 Let us consider in more detail the device for implementing the proposed method of duplex transmission of information over a two-wire circuit, shown in FIG. 3.

 A converter 2 that converts a random binary sequence into a bipolar sequence can be constructed, for example, in accordance with the circuit shown in [8] and shown in Fig. 15.

In this converter, with the help of a counting trigger T ₂ 1 and two matching circuits U ₁ and U ₂ , the even and odd sequences corresponding to the positive and negative pulses of the bipolar signal are generated, RS-triggers T ₂ 3 and T ₂ 4 are used to start the buffer amplifiers Bus1 and Bus2 and to control the RS-trigger T ₂ 2, which, in turn, in order to increase noise immunity is included in the feedback circuit and allows the sequential operation of the logic circuits U ₁ and U ₂ . The combination of positive and negative pulses in a single sequence and matching with the line is carried out by buffer amplifiers loaded with a common load, which is the transformer Tr.

 The second Converter 6 (figure 4) converts a random binary sequence into an absolute bi-pulse with the simultaneous introduction of pre-emphasis. As shown in figure 4, the second Converter contains the first to fourth RS-triggers 9-12, the first and second logic gates OR 13, 14, the first and second delay lines 15, 16 for 3/4 clock interval, the first and second buffer amplifiers 17, 18, the first and second sign detectors 19, 20, each of which consists respectively of a series-connected differential circuit 21 (22), a drive 23 (24) and a first threshold device 25 (26).

 The second converter 6 also contains the first logic element NOT 27, the third, fourth and fifth delay lines 28, 29, 30 for 1/4 of the clock interval and the transformer 31. In this case, the binary signal output of the electronic telephone exchange 5 is connected to the S-input of the first RS-trigger 9 directly, with the S-inputs of the second and third RS-flip-flops 10, 11 through the logic element HE 27, and with the S-input of the fourth RS-flip-flop 12 through the first logic element HE 27 and the third delay line 28 connected in series.

 The output of the timing signal of the electronic telephone exchange 5 is connected by the R-inputs of the first and third RS-flip-flops 9, 11 through the fourth delay line 29, and with the R-inputs of the second and fourth RS-flip-flops 10, 12 through the fourth and fifth delay lines 29, 30 connected in series .

 The outputs of the first and fourth RS-flip-flops 9, 12 are connected to the inputs of the first logical element OR 13, the outputs of the third and second RS-flip-flops 11, 10 inputs of the second logical element 14 "OR". The outputs of the first and second logic gates OR 13, 14 are connected respectively through the first and second delay lines 15, 16 and the first and second buffer amplifiers 17, 18 connected in series to the corresponding windings of the transformer 31. In addition, the outputs of the first and second logic gates OR 13, 14, through corresponding detectors 19, 20, sign changes are connected to the second inputs of buffer amplifiers 17, 18, respectively.

 Converter 6 operates as follows. The pulse sequences arriving at the inputs of RS-triggers 9-12 represent the initial binary signal, the inverse binary signal directly and delayed by T / 4, the timing sequence directly and delayed by T / 4 and T / 2.

 FIG. 16 illustrates the principle of the formation of positive and negative pulses of an absolute bi-pulse sequence, which are combined using buffer amplifiers 17, 18 loaded on a transformer 31.

 For making pre-emphasis in the absolute bi-pulse signal, sign-change detectors 19, 20 are used, with the help of which cases of occurrence in the absolute bi-pulse signal of two consecutive symbols of the same polarity are recorded. A detector of this purpose is triggered when two logical units are separated by a T / 4 gap, and does not fire when this gap is 3/4 T or 5/4 T. In the event of a sign change detector, a 6 dB attenuation is introduced into the buffer amplifier, which provides a halving amplitudes of successive pulses of the same polarity. To coordinate the moment of introducing pre-emphasis with the output signal of the sign-change detector, in each case of the appearance of two consecutive pulses of the same polarity, the signal arriving at the input of the buffer amplifier is delayed by 3T / 4.

 To carry out the inverse transformation of bipolar signal 4, the simplest circuit is used, based on the principle of half-wave rectification [9]. The circuit of the transducer 8 of an absolute bi-pulse sequence with predistortion of pulses into a binary signal is shown in Fig. 5. Since the introduced pre-emphasis should not affect the operation of the inverse converter, a threshold device with a response threshold located below the amplitude level of the double pulses of the same polarity is placed on its input.

 The Converter 8 contains a second threshold device 32, a half-wave rectifier 33, a half-wave rectifier 34, a second logic element NOT 35, the first and second logic elements AND 36, 37, the sixth delay line 38 to the 1/4 clock interval. The input of the second threshold device 32 is the input of the converter 8, and the output is connected to the inputs of a half-wave rectifier 33 and a half-wave rectifier 34. The output of a half-wave rectifier 33 is connected to the input of the second logic element NOT 35 and to the input of the sixth delay line 38. The output of the second logic element NOT 35 is connected to the first input of the first logical element AND 36, the second input of which is connected to the output of the half-wave rectifier 34. The output of the sixth delay line 38 is connected to the first input of the second logic element And 37, the second input of which is connected to the output of the first logic element And 36. The output of the second logical element And 37 is the output of the Converter 8.

 In accordance with figure 5, the absolute bi-pulse sequence with a pre-emphasis of the amplitudes of the pulses, passing the threshold device 32, is supplied simultaneously to the inputs of the half-wave 33 and half-wave 34 rectifiers.

 From the output of the half-wave rectifier 33, the signal is supplied to the second logic element NOT 35, and the same signal is fed to the input of the delay line 38. From the output of the logical second element NOT 35, the signal is fed to the first input of the logical element And 36, the second input of which receives the signal from the output of the half-wave rectifier 34. The signals from the outputs of the delay line 38 and the logical element And 36 are fed to the first and second inputs of the second logical element And 37. As a result of these transformations, the output of the second logical element AND 37 results in the initial binary sequence.

 17 illustrates the operation of this converter.

Thus, the proposed method for simultaneous transmission of signals of direct and reverse directions through a two-wire subscriber communication line without the use of echo cancellers and differential systems provides the following advantages compared to existing methods:
the use of composite cable pairs without compromising the transmission quality observed in the prototype due to the presence of reflected signals due to the absence of differential systems;
the possibility of using digital subscriber lines with attenuation exceeding 40 dB, which is the upper limit in the considered prototype, due to the absence of echo cancellers;
the use of a large number of systems on different pairs in one cable due to the absence of significant level differences during oncoming transmission of information while limiting transient effects at the near end that are acceptable for a given cable;
the ability to organize wire broadcasting of the highest class due to the upper limit of the range of transmitted frequencies without introducing significant high-frequency distortion.

Sources of information
1. System 12 Digital Eocchauge JNN Tehnical Yournal, vol. 59, N 1/2, 1985.

 2. MKKTT, v. VI, issue VI-5. Digital transit stations in integrated digital networks. Q.501 Q.517, 1984.

3. Ericsson Rewiy JSPN, 1984, vol. 61 (prototype)
4. MR Aoron. PST transmission influ exchange pkauf Bell system techuical Journal, Junuary, 1962, vol. 41.

 5. P. Bylyansky and D. Ingram. Digital transmission systems. Communication, 1985.

 6. Multichannel communication. Communication, 1971.

 7. L.M. Polyak. Probable analysis of multi-level signals. Communication, 1981.

 8. L.S. Levin and M.A. Plotkina. Digital information transfer systems. Radio and Communications, 1982.

 9. Handbook of amateur radio designer Energia, 1977.

Claims (2)

1. The method of duplex transmission of digital information on a two-wire circuit, which consists in generating digital signals on the subscriber side and the station side and simultaneously transmitting them on a two-wire line with subsequent separation, characterized in that on the subscriber side they convert a binary digital signal into a bipolar signal lying in a strip frequencies from 0 to ω ₁ , and binary digital signals on the station side are converted into absolute bi-pulse signals with a halving of the amplitudes of successive pulses coincident giving a polarity lying in the frequency band from ω ₁ to ω ₂ , where ω ₂ > ω ₁ , while the pulse width of the bipolar signal is four times the pulse duration of the absolute bi-pulse signal, the signals are separated by frequency, and they are also converted to binary digital signals.  2. The device for implementing the method according to claim 1, comprising a subscriber unit and an electronic telephone exchange interconnected by a subscriber line, characterized in that the binary signal to bipolar signal converter, the input of which is connected to the output of the subscriber unit, is introduced in the direction of the subscriber station on the subscriber side and the output is connected to the subscriber line, and on the side of the electronic telephone exchange, a low-pass filter is connected in series, the input of which is connected to the subscriber line, and a bipolar signal to binary digital signal converter, the output of which is connected to the input of the electronic telephone exchange, and in the direction of the station, the converter is a binary digital signal to absolute bi-pulse signal with a pre-emphasis on the side of the telephone exchange, the input of which is connected to the output of the telephone exchange and the input is connected to the subscriber line, and on the subscriber side are connected a filter, the input of which is connected to the subscriber line, and an absolute bi-pulse signal converter with predistortion into a binary digital signal, the output of which is connected to the input of the subscriber unit, while m binary digital signal to absolute bi-pulse signal with predistortion contains the first - fourth RS-flip-flops, the first and second logical elements OR, the first fifth delay lines, the first and second buffer amplifiers, the first and second sign-change detectors, each of which consists in series connected to the differential circuit, the drive and the first threshold device, the first logic element is NOT and a transformer, and the output of the binary digital signal of the electronic exchange is connected to the S-input of the first RS of the trigger directly, with S-inputs of the second and third RS-flip-flops through the first logical element NOT, with the S-input of the fourth RS-flip-flop through sequentially connected the first logical element NOT and the third delay line, the output of the timing signal of the electronic telephone exchange is connected to the R-inputs of the first and the third RS-triggers through the fourth delay line, and with the R-inputs of the second and fourth RS-triggers through the fourth and fifth delay lines connected in series, the outputs of the first and fourth RS-triggers are connected to the inputs of the first about the OR element, the outputs of the third and second RS-flip-flops to the inputs of the second logical element OR, the outputs of the first and second logical elements OR are connected respectively through the first and second delay lines and the first and second buffer amplifiers connected in series to the corresponding transformer windings, as well as through the corresponding the first and second sign-change detectors to the second inputs of the first and second buffer amplifiers, and the absolute bi-pulse signal to binary digital signal converter contains a second e threshold device, half-wave rectifier, half-wave rectifier, first and second logic gates AND, second logic element NOT and sixth delay line, the input of the second threshold device being the input of the converter, and the output connected to the inputs of half-wave and half-wave rectifiers, the output of half-wave rectifier to the input of the sixth delay line and the input of the second logic element NOT, the output of which is connected to the first input of the first logical element AND, the second input which is connected to the output of the full-wave rectifier, and the output to the first input of the second AND gate, a second input coupled to the sixth output of the delay line and the output is the input of the inverter.

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