Why is there no signal in the elevator? There are the following reasons:
1. Elevator structure
The elevator itself is a hollow enclosed metal space, which can shield radio waves from the physical level of du, and mobile phones transmit information through radio waves, so naturally there is no signal.
2. The signal does not cover this area
To allow the signal to cover the elevator, it is necessary to build a special elevator signal distribution system, usually by adding wall-mounted antennas and logarithmic antennas on both sides of the elevator, or installing antennas in the elevator car. The cost of this work is high, so many developers are unwilling to spend extra money. If the elevator has signal coverage, you can see obvious operator prompts in the elevator. Nowadays, with the popularity of elevator advertising machines, businesses need to install signal systems to place advertisements on LED screens in elevators through wireless networks. Recently, there are frequent crimes in elevators, elevators need to be equipped with monitors, and signal coverage of elevators is also required.
3. No signal amplifier is installed
Some elevators are not completely sealed, but there is also no signal. The reason is that the elevator shaft is often thicker concrete, which has a strong ability to absorb the mobile phone signal, which will also cause the mobile phone signal to become weak. At this time, a signal amplifier needs to be installed.
Why is the advertising machine so smooth?
Why are the advertisements in the elevator so smooth? There are the following reasons:
1. The advertising player is a playback device
The advertising player is a playback device. It has storage space inside. It can upload the advertising material materials that need to be promoted through remote control, and then it will automatically recognize and smoothly show it.
Second, it does not receive the signal from the base station, it has its own frequency band identification code
The advertising player does not need to rely on the SIM card to receive the mobile signal sent by the base station like the mobile phone. It has its own frequency band to receive signals, just like Bluetooth, even if the signal is poor, it can be retrieved.
