JPS622494B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-way communication system in, for example, a remote control system.

An example of a conventionally known remote control system is shown in Figure 1A.
and shown in B. Here, the master station 1 as a control station
1 and the carrier device 13 are connected by a carrier line 15, and a slave station 17 as a controlled station and another carrier device 19 are connected by another carrier line 21, respectively. Signals are exchanged between the two carrier devices 13 and 19 using propagation radio waves 23 such as microwaves. Such a relay means establishes an uplink circuit and a downlink link between the master station 11 and the slave station 17, allowing communication between the two. As shown in FIG. 1A, under normal conditions, the downlink signal 31 from the master station 11 is supplied to the slave station 17 as is. Uplink signal 3 from slave station 17
5 is also introduced into the master station 11 as is.

However, as shown in FIG. 1B, in the event of an abnormality such as a disconnection of the line, normal signal transmission and reception is no longer performed. It is now assumed that a line disconnection state occurs in which the carrier line 21 on the slave station side is disconnected. In such a case, the downlink signal 31 from the master station 11 is
Due to the influence of the line capacity of 1, etc., it wraps around to the uplink. Therefore, the master station 11 receives the downlink signal 31 itself as the uplink signal 35. Further, such wraparound may also occur due to a short circuit in the line 15 or 21. Due to such interference, the master station 11 receives erroneous information.

Figure 2A shows the general transmission format of signals sent and received, and one frame is defined as a synchronization signal word.
SY and n information signal words W ₁ to W _o . Such a configuration is called 1 frame n words. FIG. 2B shows a downlink signal 31 in which one frame is formed by two words. FIG. 2C shows an upstream signal 35 (in normal operation) in which n words form one frame. In such a state of transmitting and receiving signals, let us look at the signal state when an abnormality occurs as shown in FIG. 1B.

Even when an abnormality occurs, the downlink signal 31 does not change from the normal state as shown in FIG. 3A. On the other hand, as shown in FIG. 3B, the upstream signal 35 is initially (normal period P _c ) a normal upstream signal of n words;
After the line disconnection occurs (abnormal period p _n ), the signal becomes the same as the downlink signal 31.

As a measure to solve this problem, it has been proposed in the past to make the synchronization signal words SY of the downlink signal 31 and the uplink signal 35 different from each other. However, as a general rule, remote control systems use the same synchronization signal for both downlink and uplink signals. Therefore, such a measure ignores this principle and is not practical. Also, a method has been proposed in which one special bit is added to the information signal word in each of the downlink signal 31 and uplink signal 35 for identification. However, because of such identification bits, the number of bits constituting one word increases, for example, from 44 bits to 45 bits, resulting in a decrease in transmission efficiency as a remote control system. Furthermore, since it is necessary to configure the master station so as to constantly search for identification bits, the apparatus has the drawback of becoming larger and the control of processing operations becoming more complicated.

In view of the above-mentioned points, an object of the present invention is to provide a two-way communication system that can be applied to a remote control system that solves the problems caused by the looping of lines and eliminates the conventional drawbacks.

The purpose of this is to remove the period of synchronization signal from the downlink signal from the master station and send the uplink signal from the slave station to one time.
This is achieved by transmitting frames and stopping the upstream signal reception operation at the master station at least during the period when the synchronization signal in the downlink signal exists.

The present invention will be explained in detail below based on the drawings.

FIGS. 4A and 4B show examples of downlink signals and uplink signals in the present invention. The word structure per frame is such that the down signal 31 has two words and the up signal 35 has n words. The synchronization signals of these two signals 31 and 35 are reliably removed in terms of time. In other words, the uplink signal 35 from the slave station 17
automatically and continuously. At slave station 17,
After receiving the synchronization signal word SY of the downlink signal 31 sent from the master station 11 and receiving the subsequent slave station calling command in the first information signal word _W1 , the uplink signal 35 is sent from the slave station 17. Send one frame only once. After the slave station 17 finishes transmitting one frame, it will not transmit the next frame until the period K elapses until it receives the synchronization signal word SY and the first information signal word _W1 of the downlink signal 31 again. The uplink signal 35 is not sent. In this way, the synchronization signal of the uplink signal 35 and the downlink signal 31
By reliably removing the synchronization signal in time,
The synchronization signal reception operation in the upstream signal receiving circuit in the master station 11 is performed using the synchronization signal word SY of the downlink signal 31.
and a period K for two words of the first information signal word.
It can be stopped for a period of time. Therefore, the master station 1
Even if the downlink signal 31 from 1 reaches the uplink, it is possible to prevent the uplink signal receiving circuit of the master station 11 from erroneously performing a receiving operation.

FIG. 5 shows another example of the signal configuration. That is, when the downlink signal 31 has one word per frame, the slave station 17 immediately starts transmitting the uplink signal 35 upon receiving the synchronization signal word SY of the downlink signal 31, and needs to transmit only one frame. Therefore, in this case, the synchronization signal reception prohibition period K of the uplink signal in the master station 11 becomes the word period of the synchronization signal word in the downlink signal 31.

In this way, the upstream signal 35 and the downstream signal 31
temporally remove each synchronization signal word SY of the downlink signal 31, and
During the period when SY exists, the synchronizing signal receiving operation of the upstream signal transmitting circuit in the master station 11 is stopped. Therefore, it has become easier to identify the detour of the downlink signal 31 into the uplink signal 35, which was previously considered difficult. This allows line abnormalities to be detected and an alarm to be issued in the event of an abnormality.

It should be noted that the present invention can be applied not only to the master station side but also to the slave station side, and can of course be applied not only to the master station 1:slave station 1 but also to the master station 1:slave station n.

As detailed above, according to the present invention, it is possible to realize a practical two-way communication system that does not exchange erroneous information even if an abnormality occurs in the line and does not reduce transmission efficiency. .

[Brief explanation of the drawing]

Figures 1A and B are block diagrams showing the configuration of the remote control system, Figures 2A to C are signal diagrams for the system shown in Figure 1A during normal operation, and Figure 3A.
and B are explanatory diagrams of signals at the time of abnormality of the system shown in Fig. 1B, Fig. 4 A, B and Fig. 5 A,
B is a signal formation diagram for explaining an embodiment of the bidirectional communication system according to the present invention. 11... Master station, 13, 19... Carrier device, 17
... Slave station, 15, 21 ... Carrier line, 31 ... Down signal, 35 ... Up signal, SY ... Synchronization signal word, W ₁ - W _o ... Information signal word, K ... Inhibition period.

Claims (1)

[Claims] 1. Remove the synchronization signal period in the downlink signal from the master station, send one frame of uplink signals from the slave station, and stop the uplink signal reception operation at the master station at least during the period when the synchronization signal exists in the downlink signal. A two-way communication system characterized by being configured as follows.