JPS6251853A - Two-wire type time division direction control transmission system - Google Patents

Abstract

PURPOSE:To easily decide the start pulse of a reception signal by allowing the last pulse of a transmission signal and the start pulse of the reception signal to have polarities opposite to each other in the two-wire type time division bidirectional transmission system using a bipolar code. CONSTITUTION:In the waveform figure of transmission and reception signals on a line, even parity bits are added to the last of the transmission signal and the reception signal, and start pulses 1 and 3 and last pulses 2 and 4 have polarities opposite to each other in an AMI code (bipolar code). If signals are transmitted from both stations so that the first pulse of the transmission signal and the last pulse 3 of the reception signal have the same polarity, the last pulse 2 of the transmission signal and the start pulse 3 of the reception signal have polarities opposite to each other, and the variation of DC components are suppressed to reproduce the reception signal correctly.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is based on AMI (Alternate Mark).
The present invention relates to a two-wire time-division direction control transmission system that uses a K inversion code, that is, a bipolar code, and has even-numbered parity pits in the last bits of the transmitted signal and the received signal.

[Conventional technology]

Conventionally, in this type of two-wire time-division direction control transmission system, there is no regulation regarding the polarity of the leading pulse for both the transmitted signal and the received signal, and in the receiving section, the polarity of the component after line equalization is Of which, a certain level (threshold level)
The above were treated as signals.

[Problem that the invention seeks to solve]

In the conventional communication system described above, all components above a certain level are regarded as signals, so it is difficult to distinguish formal signals from level fluctuations due to DC movement, impulsive noise, and the like. Furthermore, since the transmitting and receiving sides use the same line, the transient characteristics of the final pulse of the transmitted signal cause the DC level on the line to fluctuate. At this time, when a received signal is input, the level of the received signal has been attenuated to 1/100 of the transmitted signal, and the receiving circuit receives the first pulse based on the fluctuation of the DC level. It is impossible to determine whether it is the official leading pulse from the signal level aspect, and depending on the difference in the amount of delay in the received signal, fluctuations in the DC level may not affect the received signal, so the sampled results are code analyzed. There were complications that needed to be done.

An object of the present invention is to provide a two-wire time-division direction control transmission system that can easily determine the leading pulse.

[Means for solving problems]

The present invention provides a two-wire time-division direction control transmission system that uses a bipolar code and adds an even parity pit to the last pit of a transmitted signal and a received signal. It is characterized by being set on the side.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows the transmission and reception waveforms on the line according to the present invention, 1 and 5.
・ is the first pulse of the transmitted signal when it is specified to always go to the + side, 2 is the final pulse of the transmitted signal, 3 is the first pulse of the received signal when it is specified that it always goes to the + side, 4 is the received signal is the final pulse of

The final pulse 2 of the transmitted signal and the final pulse 4 of the received signal are even parity pits. However, in the AMI code of 4, these parity pits always have a polarity opposite to that of the leading pulse. In this embodiment, since the leading pulses of the transmitted signal and the received signal are set to the + side, the final pulses of the transmitted signal and the received signal have one polarity. Therefore, the final pulse 2 of the transmitted signal and the leading pulse 3 of the received signal have opposite polarities.

FIG. 2 is an enlarged view of the section T including the final pulse 2 of the transmitted signal and the first pulse 3 of the received signal in FIG. 1, and a timing chart showing sampling and its results.

As shown in the enlarged view, the final pulse 2 of the transmitted signal causes the DC level on the line to fluctuate due to its transient characteristics.

In the figure, 10 is the threshold level on one side of the receiving circuit, 11 is the threshold level on the + side of the receiving circuit, and 12 is the receiving section.

Such an input pulse is sampled at the sampling point 20, 2.
1. The results sampled in 22 are combined with the + side pulse and -
Shown as a side pulse. First, sampling point 2
0, this point is over the DC fluctuation part that occurs in the final pulse 2 of the transmitted signal, and since the input pulse exceeds the threshold level 10 at this sampling point, one side pulse 30 is output as the sample result. . This negative pulse 30 is a pulse due to DC fluctuation occurring in the final pulse of the transmitted signal, and this pulse always appears in the opposite polarity to the leading pulse of the received signal.

At the next sampling point 21, since this point is applied to the leading pulse 3 of the received signal, a positive f pulse 31 is output as the sampling result. This +-side pulse is the sample result of the official leading pulse 3 of the received signal.

The receiving circuit determines that a sample result with the same polarity as the first pulse of the received signal corresponds to the official first pulse, and a sample result with the opposite polarity to the first pulse of the received signal is due to DC fluctuations caused by the last pulse of the transmitted signal. It can be easily determined that this is a pseudo received pulse. Therefore, it becomes possible to easily detect the leading pulse of the received signal.

In the above embodiments, the leading pulses of the transmitted signal and the received signal are set on the + side, but it is clear that the same implementation can be achieved even if they are set on the - side.

〔Effect of the invention〕

As explained above, in the present invention, the signal pulse can be defined so that the DC fluctuation caused by the final pulse of the transmitted signal has the opposite polarity to the leading pulse of the received signal. The first pulse of the signal can be determined as the leading pulse, thereby simplifying the receiving circuit and reducing the cost of the receiving section.

[Brief explanation of drawings]

FIG. 1 is a transmission/reception waveform diagram on a line for explaining an embodiment of the present invention, and FIG. 2 is an enlarged view of section T in FIG. 1 and a timing chart showing the reception state. 1.5... First pulse 2 of the transmission signal...
...Final pulse 3 of the transmitted signal ......
- Leading pulse 4 of the received signal ...... Final pulses 10, 11 of the received signal ...... Threshold level 12 of the receiving circuit ...... Reception section 20.21 .22... Reception circuit sampling point representative Patent attorney Yoshiyuki Iwasa Figure 1 Figure 2

Claims (1)

[Claims] (1) In a two-wire time division direction control transmission system that uses bipolar codes and adds an even parity bit to the last bit of the transmitted signal and received signal, the leading pulses of the transmitted signal and received signal are always on the same polarity side. A two-wire time-division directional control transmission system that is characterized by setting.