There are multiple factors affecting the signal strength from the edge-computing gateways to wireless vibration sensors, such as obstacles, interference, antenna, transmission power, receive sensitivity etc. In an industrial environment, there are many metal objects or concrete walls, which could reduce the gateway’s range to the sensors significantly. To improve the gateway’s range to the sensors, user can follow the steps below:
- Make sure that the gateway’s BLE antenna is secured to the connector. Apply some Loctite screw lock on the SMA connector to prevent the antenna from getting loose in an environment with vibrations.
- Adjust the gateway‘s mounting spot. Raise the gateway 2 meters (6 feet above ground) if possible.
- Adjust the gateway’s BLE antenna direction, make sure that the antenna body stay away from metal objects and point to the air, ideally to the direction where the wireless vibration & temperature sensors are mounted.
- When there is strong WiFi interference, the BLE signal could be interrupted significantly, since both WiFi and BLE share 2.4GHz band. Move the gateway and sensors away from a WiFi router at least 6 feet away. To lower power consumption, BLE signal is typically much weaker than WiFi signal, which makes the BLE signal overpowered by WiFi.
- Mount the wireless vibration and temperature sensors at a high spot that is clear of metal barrier if possible. Make sure that there is a clearance of the sensor’s plastic cap (where the sensor’s onboard antenna is located) from the surrounding metal barriers. The sensor’s signal will be attenuated in a tight space surrounded by metals or liquids. The sensor signal can still get through even if the machine is almost completely shielded, as long as there is 1mm (0.039 in) gap in between.
- Make sure that there is clearance among wireless sensors, and avoid mounting two sensors right next to each other.
- Turn off WiFi of the gateway when WiFi is not in use. In default, the WiFi of the gateway is turned off. If the WiFi is turned on, then please turn off the WiFi.
Extension cable for gateway antennas
A suggested extension cable for BLE & 2.4G WiFi antennas is LMR100. At 2.4 GHz (the common WiFi band), 5m (15 feet) of LMR100 has signal loss of about 6 dB (25% of the original signal. In other words,, the distance between the wireless sensors (accelerometers) and gateway is reduced to 1/4 of the original distance)
The loss in dB is linear with the cable length. So if you use 10m (30 feet) of LMR100 cable, then the loss will be 12 dB.
For better performance, please use LRM200, LMR400 or LMR600 cable. The attenuation of LMR200 is about 3dB, and LMR400 is about 1.5 dB at 5m (15 feet).
Please do not use RG174 cable, which has the worst performance. RG58 is slightly better than RG174, but is also not recommended for more than 1m (3ft) distance. RG58 has more than twice attenuation than LMR100.