Some friends of mine recently moved into their new house (in Belgium.) It is located on a small hill, next to a double-track, electrified railway. Some 2-6 trains pass by every hour, depending on the time of the day.
The ground level of the house is roughly on the same height as the power lines feeding the trains. I guess the horizontal distance between the router and the closest power line is some 40 meters. There are no obstacles in the way, except for an outside window and some small bushes.
My friends experience lots (anywhere between 5 and 20) of 'WiFi outages' per hour: periods of 10-60 seconds that not a single device in the house (cellphones, tablets, laptops,…) can make a connection to the wireless router. Horrible to watch series online, apparently.
The router itself is in the upper class of routers: it's a Linksys WRT of some 2 years old that delivers a clear and strong 2.4 and 5 Ghz Wifi-bubble around the house. Works perfect 80%-90% of the time.
We were wondering if the trains or, more likely, their power lines cause these WiFi outages. An engineer I know (working in a completely different field) told me something about 'power inversion' on the lines happening several times per hour, almost always right before a train passes. I am not sure I understood him correctly. 🙂
This issue lingers around in my head for a couple of weeks now, so I come to the esteemed panel here for answers:
- Is there indeed some sort of 'power inversion' happening on electrified railways (in Belgium?)
- Is it possible that the effects of this inversion reach into my friend's house and affect their router?
- Can they shield their router in any way to prevent the Wifi-outages?
- Is 2.4 Ghz more or less affected than 5 Ghz? (Should all their devices connect to one instead of the other?)
Thanks a lot for helping solve this riddle !
Best Answer
The answer is "Maybe". If you look at trains moving along such lines you often see sparking. This is going to cause RF interference. Additionally, the length of the power line itself might act as an antenna radiating the interference.
They need to do some experiments. Record the exact timing of the outages and see whether it correlates with trains. Also, have an AM radio on and see whether they can hear interference at the same time as wifi outages.
The key thing is to find out whether there is a correlation with something visible happening. If there is, contact the owners of the railways. Otherwise, it may well be interference from elsewhere.