Wi-Fi reception can be especially poor for rainwater tanks or tanks buried in the ground. That is why Senvolon offers two versions of the level sensor: one with an **internal Wi-Fi antenna** and one with an **external antenna connector** so you can use a separate antenna. For an external solution, **outdoor antennas with a 3-meter lead** have proven especially effective. These reliably route the Wi-Fi signal out of the shaft, giving the sensor a stable connection. This guide helps you decide which sensor variant suits your scenario and how to correctly judge Wi-Fi quality. If you would still like a general comparison: our page on monitoring the water level in a rainwater tank gives an overview of sensor technology and use cases.
1. Checking Wi-Fi Reception at the Rainwater Tank
Testing this is simple:
- Go with your smartphone to the spot where the sensor will be placed
- Check the Wi-Fi signal strength
- If there is little or no reception, use a Wi-Fi repeater to extend the signal to the rainwater tank
2. How Material Affects Wi-Fi Reception
Signal attenuation depends heavily on the material and installation depth:
- Plastic lets Wi-Fi through largely unhindered
- Concrete reduces the signal significantly
- Steel blocks Wi-Fi completely
What matters most is:
- the material of the lid
- the depth at which the sensor is mounted
The deeper and the more solid the material, the harder it becomes to get stable reception.
3. When an External Antenna Is Necessary
An external antenna is recommended for:
- Steel lids
- Reinforced concrete
- generally weak Wi-Fi signals
- deep sensor positions
- rainwater tanks or shafts outdoors
In these cases, the antenna should be mounted outside the shaft or rainwater tank.
4. Checking the Wi-Fi Signal Strength in the Level Sensor (RSSI)
After installing the Senvolon sensor, you can view the reception strength under More. It is displayed as the RSSI value (Received Signal Strength Indicator).
Format:
- Unit: dBm
- negative values
- closer to 0 = stronger signal
Examples:
- -30 dBm: very strong signal
- -90 dBm: very weak, unstable
5. Interpreting RSSI Values
| RSSI Value | Meaning |
|---|---|
| -30 dBm | Very strong signal (near ideal) |
| -50 to -60 dBm | Good signal quality |
| -60 to -70 dBm | Medium, still works reliably |
| -70 to -80 dBm | Weak, dropouts possible |
| -90 dBm or worse | Very weak, no stable connection |
For the level sensor to send data reliably, the value should not be worse than -80 dBm.