Instance site
The site is located in the junction of China and Mongolia in Hami, Xinjiang. The ZigBee network is used for automatic drip irrigation system. The application area is more than 40,000 mu. Because the land in this area is mostly Gobi desert, the annual rainfall is very small, and the agriculture adopts automatic monitoring of drip irrigation. Form, the system uses different automatic drip irrigation modes according to different seasons, different time periods and different weathers, and the planting area cannot use wired network, so the ZigBee network with low-level power consumption is the best choice.
Figure 1 Application site of agricultural automatic drip irrigation system in Hami area of ​​Xinjiang (all melons!)
During the simulation site debugging phase, all nodes of the ZigBee network can be collected and controlled normally, but there are many incomprehensible phenomena after installation on the site. The other engineer has no professional network analysis equipment on site, and the ZigBee network coverage is too much. Huge, fault analysis has basically become impossible. After entering the detailed technical communication between the two parties, our company dispatched engineers and carried the professional network analysis tool ZigBee Analyser to the site for network troubleshooting.
Figure 2 Zhiyuan engineers go to Hami site to use ZigBee analyzer for troubleshooting
One of the field cases: hidden faults with uneven signal coverage
One of the smaller irrigated areas on the site (about 1 square kilometer), we use this simplest small network as an analysis case, there are many valve controller nodes in the field can not control, but the other party has previously performed node single point detection, all The nodes are all working normally, the node configurations are all correct, and all of them are in the communication range, and some nodes are not far away. This kind of situation belongs to the hidden problem of the wireless network, and the general debugging method is difficult to locate the problem.
Figure 3 Controlling the well house cannot control part of the valve controller
For such a wide range of ZigBee control acquisition networks, the ZigBee network analyzer is used to monitor the actual operation of the entire ZigBee network, and the problem can be exposed in an instant. Zhiyuan engineers used the ZigBee network analyzer to capture network operation information of the network in the small area.
Figure 4 Analyzer analysis tool Packet-Analyzer for network operation status monitoring
Step 1: In the network coverage, the ZigBee analyzer is used for network monitoring at a fixed point. The monitoring finds that the downlink information of the route is normally transmitted, but there is a certain probability that the faulty terminal node cannot be reached normally, and the Packet-Analyzer data shows the wireless signal coverage distance. It is completely enough. It is generally believed that there may be problems with the node receiver.
Figure 5 ZigBee Analyser evaluates the wireless channel
The second step is to perform data transmission and reception test on the faulty node, but no problem is found. However, when the signal strength is captured in the accessory of the node, it is found that one of the routing nodes has a weak downlink signal and the receiving sensitivity of the adjacent terminal. The signal strength of other directions to the same distance from the routing node is normal. As shown below, the target of the problem is determined by the router with the attachment number 0X0007.
Figure 6 Analysis of downlink data of routing nodes
For the analysis of the router signal, it can be concluded that the 0x0007 routing node has uneven signal radiation, and its direction is similar to the following figure, because the faulty node (in fact, there is no problem with the node) is just in the router. The signal is radiated in a blind zone, and the accessory has no multiplexing router, which causes the downlink data to fail to arrive normally.
Figure 7 routing node direction diagram
Find the routing node in the area and check it in detail. In fact, the routing device works as normal, and the functions and performances are also not found abnormal. In the previous analysis, we can focus on the antenna more accurately. On the above, the antenna was inspected and found that the antenna base suction cup was dropped and fixed with tape. In fact, this has seriously affected the integrity of the antenna, resulting in serious influence on the directionality of the standing wave and the antenna, and the problem will not be This causes serious network failures and is generally difficult to find.
Figure 8 Incomplete routing of the antenna section of the routing section results in uneven signal radiation
Of course, the above is just a small example of ZigBee network detection in a drip irrigation area. Other drip irrigation areas have more network detection such as: network topology analysis, signal stability test, data message analysis, channel and energy scanning, node signals. Output conformance test (ZigBee module incoming inspection is necessary, one of the old projects in the field uses a supplier's ZigBee module, due to the large difference in consistency, resulting in large-scale network failure), etc., due to space limitations, Follow up and share with you!
On April 8th, there was a wireless communication technology seminar to guide the development of the offline, so that the development of technical problems is worry-free ~!
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