Figure 1
Flow diagram of data tracking analysis at GNC.
Table 1
Examples of factors influencing various types of abnormal variations.
| Influencing factors | Examples |
|---|---|
| Observation system malfunction | Sensor malfunction, host computer malfunction, data requisition malfunction, communication unit malfunction, lightning avoidance system malfunction, battery malfunction, insufficient power source, AC/DC switching interference, simulation devices malfunction. |
| Natural environment | Temperature, humidity. |
| Site environment | Infrastructure construction, vehicles, subway and light rail, HVDC, earth resistivity, power supply interference, factory operations. |
| Human interference | Calibration, maintenance equipment, agriculture. |
| Unknown reasons | The cause of changes cannot be confirmed after exclusion of effects due to observation system malfunctions, the natural environment, the site environment, or human interference. |
Figure 2
An example of the pattern of subway interference at Sheshan station.
Figure 3
An example of an interference pattern caused by HVDC circuit debugging at Wuhan station.
Figure 4
An example of data drift caused by poor insulation of the recording room at Wanzhou station.
Figure 5
An example of interference patterns due to a data requisition crash at Wushi station.
Figure 6
An example of suspected environmental interference at Taiyuan station.