SKF Wireless Machine Condition Sensor
77
Service Manual
8
RF Interference and Solutions
RF Interference
Sources
RF interference sources include:
•
WiFi
•
Bluetooth
•
Multiple 802.15.4 networks
•
Microwave oven, cordless phones, miscellaneous, etc.
Symptoms
RF interference symptoms include:
•
Reliability is less than 99.9%.
•
The stability of a large number of paths is less than 60%, even when RSSI is better
than -70 dBm.
•
Sensors are within operating range (50 m) but have poor path stability, less than
50%.
•
Upstream latency is greater than 30 seconds.
•
Average queue occupancy is higher than one, and the maximum occupancy is
higher than three. The average queue and maximum queue can be found in the
Solutions to RF Interference
Potential solutions to RF interference include:
•
Identify the source of the interference and remove it.
•
Increase the number of neighbors.
•
Channel blacklisting (see details below).
Channel Blacklisting
You can use frequency planning and blacklist those channels on the gateway known to
overlap with heavily used WiFi channels.
Or
the reverse, study the WIFi channels in use
with a laptop and a program like MetaGeek Wi-spy ISMB spectrum analyzer and
software, and then determine the available frequency space and the channels
corresponding within WirelessHART. If there are other wireless networks in the area