# Wifi interfere with OTA



## PCampbell

I find it hard to believe but a guy at work has RV at a park that added wifi for the park with multiple TX points. He got 10 or more channels with the antenna mounted on top of the RV. When the wifi went online he lost all but two?? It is a 2.5ghz system, the highest tv frequency is about 700mhz. Anybody see this and if so what did you do.


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## photostudent

No RF transmitters are perfect and can generate some harmonics. Band pass filters were a common cure for SD TVs and should work for HD as well.


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## P Smith

then the WiFi equipment is in violation of FCC rules and must be shutdown, any RF engineer with spectrum analyzer and own antenna would find a source of the RF interference
while I don't see how it happen, I wouldn't blame the WiFi access points


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## kenglish

If the Wi-Fi is really at 2.5 GHz, it should not be a problem, unless the TV signals are very weak and the antenna is very close to the Wi-Fi.
Other frequencies could be used, and if those are closer to the TV frequencies, they may be overloading the sets' front-end, or overloading any preamps being used for TV.

The other idea is, the router for the Wi-Fi system may be causing interference, or the customers who are now using their Wi-Fi may have routers that are interfering.


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## PCampbell

The stations are weak and the antenna is less than 50ft from the wifi antenna.


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## P Smith

All the postings will not fix the problem.

You should pass it to hands of professional RF guy

or

buy cheap USB DVB card what support SDR, install SDR_Sharp [free] software and drivers, scan the spectrum and walking around find the damn source of interference !


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## kenglish

Is there a preamplifier on the TV receiving antenna? I suspect there is, if it's designed to go on an RV.
The close-by Wi-Fi signal is possibly overloading the (very wideband) input of the antenna amplifier.
Replacing, or seriously modifying, the antenna is all that would help.

If no amplifier...........
At the UHF frequencies that are used for TV, it might be advisable to put several of those Radio Shack ferrites on the cable near the TV antenna, and several on all of the cables that feed the Wi-Fi antenna. Of course, some of the interference from the Wi-Fi may be radiated directly from the Wi-Fi equipment, not all thru the antenna. That would take a few more ferrites on the power and data cables.


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## P Smith

kenglish, we are dissing WiFi 2.4 or 5 GHz band equipment's possible polluting on RF 40-900 MHz band; while it is possible to create EMI for that, we must count the max power of WiFi devices (I recall 500 mW per FCC rules), probably 200 mW or normally 100 mW.
Perhaps we have a deal with _faulty_ device(s), in this case it must be discovered and fixed ASAP.



I would call FCC and complain - they have special road service what would come and measure and will help find the problem.


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## PCampbell

Problem solved, the park changed the channel of the Wifi.


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## P Smith

the WiFi device(s) is still not kosher if it emit parasitic signal in low RF band (VHF/UHF) while it must stay with 2.4 GHz


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## PCampbell

I thought all models needed to be tested before release to the public but quality control may not be all that good.


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## kenglish

I'm going to send a link to this thread, to Charlie Rhodes, who is the leading expert on DTV interference.


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