中文
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At present Chinese power dispatching network is equipped with SDH equipment and PCM equipment to carry the voice, telecontrol, computer information and other data required for power production. However, the specificity of PCM equipment needs to be used in pairs, so it also has some drawbacks in the process of use.
There are many communication stations such as dispatching centers, substations, and power stations, and there are fewer types of communication services in each substation or power station. Generally the power dispatching data that needs to be transmitted mainly includes dispatching telephone information, administrative telephone information, and automation moving information. Moreover, the current substation or power station adopts the traditional point-to-point communication mode, that is the dispatching center station and each substation or power station are each equipped with a set of PCM equipment. If there are 5 substations, it means that the dispatching center has 5 PCM devices respectively. Five PCM devices in five substations are transmitted point-to-point (Figure 1). The traffic for the general substation is not large. Each station is about 10~20 channels, which can meet the demand. The 2M channel can transmit 30 channels and it only takes about 1/2 of the 2M circuit. Therefore, this networking method does not make full use of the 2M circuit.
<p style="text-align:center>Figure 1 (PCM device point-to-point transmission)
In response to the above situation, the digital cross-connect device (DXC) can solve this problem well. It is capable of cross-connecting any 64k time slot. The device is equipped with multiple 2M connection ports. Through the built-in cross matrix and software control, a certain user time slot of an E1 port can be connected to any E1 user's time slots of the port, thereby implementing the time slot cross-connection function of different E1 ports.
The digital cross-connect device works very simply. It can cross-connect the first time slot data in the 2M circuit of the first channel to the first time slot data in the 2M circuit of the second channel. If there is no digital cross-connect device, the first channel first time slot in the 2M circuit can only be connected to the first time slot data in the 1M 2M circuit. As shown in Figure 2, the 2M circuit PCM signals from the dispatch center are respectively sent with the information of dispatching telephone service, telecontrol service and conference telephone service, and are sent to the 64 Kbps digital cross device of the dispatch center; 64 Kbps digital cross device with its time slot crossing function, the situation of different PCM settings from 5 remote stations fully utilizes the slot positions of each module of the PCM board, reducing the number of PCM boards in the dispatch center and saving money. The same service is selected and aggregated into one or more 2 Mbps signals. This feature is similar with the post office's ability to sort mail by greatly improving the efficiency of the postman. This situation greatly improves the slot utilization of each module of the PCM cards, reduces the number of PCM cards in the dispatch center, and saves money.
Figure 2 (1 PCM device corresponds to multiple PCM devices)
