JPS587099B2 - Multipoint data transmission/reception system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multipoint data transmission/reception system, particularly a multipoint data transmission/reception system in which a center device and a plurality of terminal devices are linked via modems each having an automatic equalizer. For example, when the automatic equalizer in one terminal device goes into a divergent state, it emits an interference signal that causes the automatic equalizer in the center device to go into a divergent state, and the modem in each terminal device receives a carrier signal from the center device side. The present invention relates to a multipoint data transmitting/receiving system that prevents a divergence state from continuing undesirably by configuring not to emit a synchronization signal in response to an off state.

It is known that modems with automatic equalizers are used in point-to-point data transmission and reception systems.

In this case, the resynchronization procedure when one of the automatic equalizers becomes divergent is C. C. I. T. T
Recommendation V. It is given by 29.

As mentioned above, this resynchronization procedure is for a point-to-point data transmission/reception system, and if you try to apply the resynchronization procedure as it is to a multipoint data transmission/reception system, see Figure 2. As will be described later, the divergence state may continue undesirably.

An object of the present invention is to solve the above-mentioned problems, and a multipoint data transmitting/receiving system according to the present invention is a multipoint data transmitting/receiving system configured such that a center device transmits and receives data to and from a plurality of terminal devices. In a data transmission/reception system in which the center device and each of the plurality of terminal devices are linked via a modem each equipped with an automatic equalizer, the modem of the center device has its own automatic equalizer. A continuous divergence state detection unit that detects a continuous divergence state, and a training signal to the terminal device side after the carrier is temporarily turned off based on the output from the continuous divergence state detection unit. The modem of each terminal device is configured to include at least a resynchronization signal sending section that sends out a resynchronization signal, and the modem of each terminal device has a divergence state detection section that detects that its automatic equalizer is in a divergence state; at least a disturbance signal transmitting section configured to transmit a disturbance signal to cause an automatic equalizer in a modem of the center device to diverge based on the output from the divergence state detection section; It is characterized in that it is configured not to send out a synchronization signal in response.

This will be explained below with reference to the drawings. Figure 1 is an explanatory diagram explaining the point-to-point data transmission/reception system and the resynchronization procedure in that case, and Figure 2 is a multi-point data transmission/reception system.
FIG. 3 is an explanatory diagram illustrating an embodiment of a data transmission/reception system and problems in the case. FIG. 3 shows the configuration of an embodiment of a center device modem and a terminal device modem used in the present invention.

In FIG. 1, 1 represents a center device, 2 a center device modem, 3 a line, 4 a terminal device modem, and 5 a terminal device.

In the case of a point-to-point data transmission/reception system, for example, a center device 1 and a terminal device 5 are linked one-to-one via a line 3, and face each other via a modem.

For 9600 bps modems, each modem 2, 4
Each terminal is equipped with an automatic equalizer, and the terminal device modem 4
The automatic equalizer in the center device modem 2 is trained to correctly receive the transmission data from the center device 1, and the automatic equalizer in the center device modem 2 is trained to correctly receive the transmission data from the terminal device 5. .

That is, for example, the training is performed by transmitting a synchronization signal including a training signal when the power is turned on.

In a point-to-point data transmission/reception system as shown in FIG. 1, if the automatic equalizer in the terminal device modem 4 goes into a divergent state for some reason, C. C. I. T. T. Recommendation v. The following resynchronization procedure according to 29 is taken.

That is, (1) when the modem 4 detects that its automatic equalizer has diverged, it once turns off the carrier, then turns it on, and sends out a synchronizing signal.

(2) The modem 2 detects the off/on state of the carrier from the other party, recognizes that the automatic equalizer in the other party's modem is in a divergent state, and sends out a resynchronization signal.

(3) Needless to say, the resynchronization signal includes a training signal, and the automatic equalizer of the terminal device modem 4 is trained by the resynchronization signal.

That is, the resynchronization procedure is completed. Note that the resynchronization signal may be considered to include a training signal that is issued following the synchronization signal that performs the off-on operation.

Of course, no particular problem will arise if the synchronization signal itself is used to generate a training signal following the off-on, and has the same form as the resynchronization signal.

The resynchronization procedure as described above is the same even if the automatic equalizer in the center device modem 2 diverges first.

However, the resynchronization procedure described above is compatible with a point-to-point transmission/reception system, but problems arise when applied to a multipoint data transmission/reception system as shown in FIG.

In FIG. 2, symbols 1, 2 . 3 corresponds to FIG. 1, 4A, 4B, . . . , 4N are terminal device modems, and 5A, 5B, . . . , 5N are terminal devices.

In the case of a multipoint data transmission/reception system, for example, data transmission is first performed between the center device 1 and the terminal device 5A, then data transmission is performed between the center device 1 and the terminal device 5B, and so on. Data transmission is performed between the center device 1 and the terminal device 5N, and data transmission is performed between the center device 1 and the terminal device 5A...1...
It is made to go.

For this reason, if the resynchronization procedure described with reference to FIG. 1 is applied as is, the following situation will occur.

That is, (4) Now, the center device modem 2 and each terminal device modem 4A
, 4B, .

(5) In this case, if the above resynchronization procedure is followed, the modem 4A will send a synchronization signal to the center device modem 2 without any consideration of the system operating status.

(6) For example, terminal device modem 4B,..., 4N
Assume that the synchronization signal reaches the center device modem 2 during a period in which there is no data transmission between the center device modem 2 and the like.

In the case of a multipoint data transmission/reception system, the center equipment modem 2 will regard the arrival of the synchronization signal as a signal for normal data transmission.

, Therefore, the center equipment modem 2 cannot recognize that the automatic equalizer in the terminal equipment modem has generated a divergence state, and the center equipment modem 2 does not send out a resynchronization signal according to the above-mentioned resynchronization procedure. .

That is, the divergence state of the automatic equalizer in the terminal device modem 4A is ignored.

(7) Also, on the other hand, for example, the terminal device 4B,...
Assume that the synchronization signal is issued during a period during which data transmission is occurring between the center device modem 2 and the center device modem 2, and that the synchronization signal is correctly received by the center device modem 2.

In this case, the center device modem 2 determines that the terminal device modem is in a divergent state, and according to the resynchronization means,
A resynchronization signal is sent as in the above process (2).

(8) Therefore, the diverged terminal modem 4A processes the above process (
Complete the resynchronization as in 3).

However, other terminal modems 4B, .

That is, the center device modem 2 is the terminal modem 4B,...
..., the above-mentioned off-state in the resynchronization signal from 4N.
In response to the on state, the terminal device will again be determined to be in the divergent state, and this state will be repeated.

In order to solve the above problem, the name terminal device modem 4A,
For 4B, ..., 4N, the following (A), (B) (
C).

That is, (A) when the automatic equalizer of the center device diverges, an interference signal sufficient to cause the automatic equalizer in the center device modem 2 to diverge is continued to be transmitted to the center device modem 2.

(B) The above-mentioned interference signal is continuously transmitted until the automatic equalizer in the center equipment modem 2 diverges and a predetermined time has elapsed until it is detected that the center equipment modem 2 is turned off.

(C) Even if it is detected that the center device modem 2 has turned off the carrier in response to the interference signal as described in (B) above,
Unlike the point-to-point data transmission/reception system described above, no resynchronization signal is sent.

On the other hand, the center device modem 2 is provided with the following function (D).

In other words, (D) If the automatic equalizer detects that it is in a divergent state for a predetermined period of time or more, it assumes that there is an interference signal from the terminal device modem and switches the carrier. It is turned off and then turned on to send a resynchronization signal.

By providing the functions (A), (B), (C), and (D) above, the automatic equalizer is trained in a terminal device modem that is in a divergent state to eliminate the divergent state.

Further, in the center device modem 2, the automatic equalizer is reset and trained in response to the next data transmission sent from the terminal device side.

That is, as in the resynchronization procedure described with reference to FIG.
The automatic equalizer in the center device modem 2 will not be confused by resynchronization signals sent from each terminal device side.

FIG. 3 shows an embodiment of the configuration of a center device modem and a terminal device modem.

Symbols 1, 2, 3, 4A, 5A in the figure correspond to FIG. 2,
6 is a transmitter, 7 is a resynchronization signal transmitter, 8 is a receiver, 9
10 is an automatic equalizer, 10 is a continuous divergence state detector, 11 is a divergence state detector, 12 is a timer, 13 is a transmitter, 14 is an interference signal transmitter, 15 is a receiver, 16 is an automatic equalizer, 17 18 represents a divergence state detection section, and 18 represents an interference signal sending condition determination section.

Now, if the automatic equalizer 16 in the terminal device modem 4A diverges, the divergence state detection section 17 detects this.

When the receiving section 15 detects a carrier, the determining section 18 determines that the interference signal transmission condition is satisfied and starts the interference signal transmission section 14.

As a result, the interference signal continues to be transmitted via the transmitter 13.

In the center device modem 2, the automatic equalizer 9 is put into a divergent state in response to the above-mentioned interference signal.

The divergence state is detected by the divergence state detection section 11, and the timer 12 is started.

When the timer has elapsed for a predetermined time, the resynchronization signal sending section 7 is started, and after turning off the carrier once, the resynchronization signal is transmitted via the transmission section 6.

Each terminal modem detects a carrier-off, but does not send out a resynchronization signal, unlike in the resynchronization procedure described with reference to FIG.

Then, by the resynchronization signal from the center device side,
Train your own automatic equalizer 16.

That is, in the terminal device modem 4A in the divergent state,
Based on the carrier off from the center device modem 2, the determining section 18 turns off and stops transmitting the interference signal, and the divergence detecting section 17 is reset.

The automatic equalizer 16 will then be trained by the transmitted resynchronization signal.

The automatic equalizer 9 in the center device modem 2 is set to a reset state, and the next time there is data transmission from any one terminal device, a training signal is transmitted at the beginning of the data. will be trained.

In addition, in the center device modem 2, when the automatic equalizer 9 enters the divergent state, the timer 12 detects that the divergent state has continued for a predetermined period of time without immediately treating it as an interference signal from the terminal device side. The conditions may be considered to be based on the following reasons.

That is, for example, the automatic equalizer 9 may enter a divergent state due to a lightning strike or the like while receiving data from the terminal device 5A.

In such a case, the carrier will be automatically turned off when the transmission from the terminal device 5A ends.

In this case, the center device 1 takes measures to make the terminal device 5A retransmit data.
The automatic equalizer 9 is automatically trained when data is retransmitted from the terminal device 5A.

In the case of divergence in the automatic equalizer 9 itself, since there is an automatic recovery function as described above, interference from the terminal device side can be prevented as long as the divergence state continues for a predetermined period of time. It is made to be used as a signal and a signal.

As explained above, according to the present invention, the divergent state in each terminal device modem is not left unattended;
Moreover, the center device modem will not inadvertently send a resynchronization signal to each terminal device modem.

In other words, in the center equipment modem, even if the automatic equalizer diverges, it will automatically recover after a predetermined period of time, so it is not necessary to specifically transmit a resynchronization signal from the terminal equipment side. It is used to cancel the divergence of the automatic equalizer in the terminal device modem.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram explaining the point-to-point data transmission/reception system and the resynchronization procedure in that case.
The figure is an explanatory diagram illustrating an embodiment of a multipoint data transmission/reception system and problems in that case, and FIG. 3 shows the configuration of an embodiment of a center device modem and a terminal device modem used in the present invention. In the figure, 1 is a center device, 2 is a center device modem, 3 is a line, 4 is a terminal device modem, 5 is a terminal device, 6 and 13 are transmitters, 8 and 15 are receivers, and 9 and 16 are respective receivers. An automatic equalizer, 7 a resynchronization signal sending section, 10 a continuous divergence state detecting section, 14 an interfering signal sending section, 17 a divergent state detecting section, and 18 an interfering signal sending condition determining section.

Claims (1)

[Scope of Claims] 1. A multi-point data transmission/reception system configured such that a center device transmits and receives data to and from a plurality of terminal devices, wherein the center device and each of the plurality of terminal devices each transmit and receive data automatically, etc. In a data transmission/reception system connected via a modem equipped with an equalizer, the modem of the center device includes a continuous divergence state detection section for detecting that its own automatic equalizer is continuously in a divergence state; The device is configured to include at least a resynchronization signal sending unit that once turns off the carrier based on the output from the continuous divergence state detection unit and then sends a resynchronization signal including a training signal to the terminal device side. The modem of each of the terminal devices has a divergence state detection section that detects that its own automatic equalizer is in a divergence state, and an automatic equalizer in the modem of the center device based on the output from the divergence state detection section. A multifunction device comprising at least a disturbance signal transmitting section for transmitting a disturbance signal that causes the equalizer to diverge, and is configured not to transmit a synchronization signal in response to the resynchronization signal from the sensor device side. Point data transmission/reception system. 2. The multifunction device according to claim 1, wherein the modem of each of the terminal devices is configured to detect a carrier-off state from the center device and continues to send out the interference signal from the interference signal sending unit. Point data transmission/reception system.