Why the actual transmission distance of the wireless module is different from the distance advertised by the manufacturer

After some customers have purchased the wireless module, when actually measuring the distance, they found that the actual transmission distance of the wireless module is not the same as the distance advertised by the manufacturer's salesperson when they purchased it, or it did not reach the distance advertised by the manufacturer. Why does this problem occur? What? After investigation, it is found that the following problems will cause the transmission distance to be different from the advertised distance.

1. There is an obstacle between the two wireless modules. When the manufacturer measures, the environment is ideal. There are no obstacles between the two wireless modules, but the user's environment cannot do this. Generally, there are obstacles. The reinforced concrete will shield the signal, so the actual distance will be shorter.
2. Electromagnetic interference signal. The environment used by wireless module manufacturers is relatively pure, and there is little electromagnetic interference, while the environment used by users will have external interference, which will increase the error rate of data transmission and abnormal calibration, which in our view is shortening the distance.
3. The height of the antenna. The height of the antenna erected by the manufacturer is very high, but for the user, it is higher if it can be erected higher, because lightning protection measures must be considered when erecting it, and the loss caused must also be considered comprehensively.
4. The power supply problem of the wireless module. Some users use battery power supply, and the distance will also be affected when the battery voltage drops during use. Although some are powered by a power supply, the current is not large enough, and the distance will be affected when used.

The above is the reason why the actual transmission distance of the wireless module is not the same as the distance advertised by the manufacturer, so you must have a certain number of the transmission distance that the manufacturer said. This distance is the reference distance, and the actual distance will be affected by many factors.