DD269507A1 - CIRCUIT ARRANGEMENT FOR RICH-UP TERMINATION IN THE TIME SEPARATION METHOD - Google Patents

Abstract

With the circuit arrangement, an increase of the efficiency of the time separation method used in digital transmission of the message on a transmission medium for the separation of the transmission directions is to be enabled. According to the invention, this object is achieved in that, when several source words are combined, the source word is split and the resulting parts are transmitted at different speeds, the higher frequency channel being transmitted with an AMI coded line signal and for shaping the spectral range both in the transmit - As well as a high-pass first order is used in the reception branch. For the low-frequency part, the second-order bipolar code is used as a line signal in conjunction with first order low-pass filters in the transmission and reception branches.

Description

Title of the invention

Circuit arrangement for range increase in Zeitgetrenntlageverfahran

Field of application of the invention

The invention relates to a circuit arrangement which enables an increase in the performance of the time separation method used in the separation of the transmission directions of digital signals on 2-wire lines.

Characteristic of the known state of the art

The inclusion of digitized telephony in ISDN (Integrated Services Digital Network) places increased demands on the transmission system to be used. Since an essential requirement of telephony is that of simultaneously transmitting the information flows in both directions, the selection of a suitable method for directional separation is of great importance.

At present, five basic processes are known to accomplish this task:

In four-wire operation, each direction of transmission is provided with a 2-wire cable. With double the amount of transmission medium, complete freedom from reaction and minimum circuit complexity are achieved for directional stabilization / 1 /.

In Gleichlageverfahren the Riehtungstren ^ ung by suppression of the transmission signals by means of a bridge (fork) circuit made so that only the signals to be received can reach the receiving branch (DE 29 11 866). The necessary return loss is improved by an echo compensation device. The achievable range depends essentially on the quality of the compensation. Achieving high return loss requires considerable circuitry effort.

In the frequency separation method, each transmission direction becomes a carrier frequency to which the information to be transmitted is modulated, or a certain line having a frequency separation by different ones

Location of the center frequencies of the power density spectra allows, assigned / 1 /.

This assignment of different carrier frequencies or line codes per transmission direction allows a simultaneous transfer to only one pair of wires. However, this saving in transfer money must be paid for with a high level of circuit complexity and a shortening of the range.

The correlation method makes it possible to separate the transmission directions by using different line codes from the class of orthogonal punctures with associated matched filters or correlation receivers for the different transmission directions and by detecting the correlation functions (DD 235 149 A 1). It is a good interference suppression with the z. Z. available components facing difficult realization.

In the time-separation method, the directional separation on the 2-wire line is achieved by multiplexing the information bursts to be transmitted and the information bursts to be empowered (DS 27 17 592). The necessary increase of the transmission speed to more than twice the source signal leads to a reduction of the range.

Object of the invention

The aim of the invention is a circuit arrangement which makes it possible to increase the transmission range of the time separation method used in the digital transmission of signals in bidirectional traffic.

Explanation of the essence of the invention

It is an object of the present invention to provide a circuit arrangement for increasing the transmission range of the time-separation method used in the simultaneous transmission of digital signals over a transmission medium in both directions.

According to the invention, this object is achieved by

that at least two words of the source signal are combined and transmitted in an information burst,

the separation of characters is such that the number of characters in the two channels is at least 1: 8 (i.e., the higher frequency channel is operated at at least 8 times the transmission speed of the lower frequency channel),

- That for the higher frequency channel of the bipolar code 1st order (AMI code) as a line code in conjunction with a high pass first order in the transmitting and receiving branch and for the low frequency channel of the second order bipolar in conjunction with a low pass 1st order in Transmitting and are used in the reception branch for each transmission direction.

embodiment

The invention is based on an ISDN basic access, consisting of two B-channels with 64 kbits each (corresponding to one 8-bit word each) and a D-Kansl with 16 kbits (corresponding to a 2-bit word), ie one In addition, it is assumed that the duplex channel is realized by the time division method with bursts of three 18-bit words each

 It shows

Figure 1 shows the block diagram of Ütertragungsanordnung for a transmission direction.

According to FIG. 1, the 54-bit burst of the source signal is split in the ratio 1: 8 so that the D channel and B channels are separated. That when three words are combined into one burst, the 6 bits of the D channel are stored in the shift register SR 2 and the 48 bits of the B channels are stored in the shift register SR 1. At the time of transmission, the shift registers are different with different clock frequencies

- T1 = 8 · Τ2 - read out.

At this time, the information of the shift register SR 1 in the line encoder LC is converted into the AMI code. A first-order high-pass filter shapes the spectrum of this transmission signal in such a way that the spectral components which overlap with the low-frequency spectrum of the second channel are suppressed. The information of the shift register SR 2 are converted into the Leibungscodierer LC 2 in the Bipolarcode 2nd order and freed by the subsequent low-pass filter from the overlapping with the higher-frequency spectrum spectral components.

The thus formed signals of LC 1 and LC 2 are combined via a summing, fed to the line circuit LA and transmitted via the line Ltg for line stopping the remote station within the transmission cycle. In the remote station, the received sum signal is separated again by a high pass 1 · order and a low pass 1 · order.

Thereafter, the decoding of the signals in the decoders DC 1 and DC 2 and the injection of the decoded signals - the higher-frequency signals in the shift register SR 3 and the low-frequency signals in the shift register SR 4 *

Thereafter, the further processing of the total information can take place.

Analogously, the next transmission cycle is traversed in the opposite direction.

Claims (2)

claim Circuit arrangement for increasing the time in the time-separated loop 2 shift registers, 2 Leitungsodierern with subsequent Filterschcltungen and a summing and a line connection for the transmission circuit, and line connection and filter circuit, decoder and shift register (for each egg two channels) characterized in that the hb'herfrequente channel with the division ratio corresponding higher transmission speed the low-frequency channel is operated and that for the higher-frequency channel of the bipolar code 1 · order (AMI code) as a line code in conjunction with a high pass first order in the transmitting and receiving branch and for the low-frequency channel of the second-order bipolar in conjunction with a low-pass filter first order in the transmitting and receiving branches are set for each transmission direction. IMit tad μ IUIj ₁ V;