View Full Version : Nano 5G interferring with TV reception in Ireland
dolanp
08-27-2009, 07:08 AM
hi,
We have some Nano 5G radio units installed and they are interferring with TV reception on the VHF band in Ireland.
We have moved the units as far as possible from the external TV antenna(20Mtrs) with no visual between both antennas but they still interfer. We also reduced the power to minimum and changed the frequency with no avail.
This is now causing issues and we had to replace some units with a Mikrotik replacment and this seems to cure the problem.
Any ideas would be welcome.
hi,
We have some Nano 5G radio units installed and they are interferring with TV reception on the VHF band in Ireland.
We have moved the units as far as possible from the external TV antenna(20Mtrs) with no visual between both antennas but they still interfer. We also reduced the power to minimum and changed the frequency with no avail.
This is now causing issues and we had to replace some units with a Mikrotik replacment and this seems to cure the problem.
Any ideas would be welcome.
Is that with external antenna's being used on the CPE's ?
If not, Maybe it the radiating angle is what makes the difference between the unit's?
I know for a fact that *Cheap* T.V mast amp's will cause RFI !
Have the same issues in fringe areas for poor t.v reception, and I always avoid installing the units near t.v antennas with amps. (both analogue and digital).
Interesting though, Next install i'll do that has a t.v amp, I will experiment with both unit's using grids.
If I had a spectrum analyser id also be checking the harmonics difference between the two brands.
Also are you crossing the t.v's rf path, ie pointing unit towards the tv antenna?
dolanp
08-28-2009, 01:33 AM
Also are you crossing the t.v's rf path, ie pointing unit towards the tv antenna?
The Nano is only using its internal antenna. Actually the nano is pointing roughly in the same direction as the TV antennas. Even if I change the SSID so the nano does not associate with the AP, we still get interference.
The Nano is only using its internal antenna. Actually the nano is pointing roughly in the same direction as the TV antennas. Even if I change the SSID so the nano does not associate with the AP, we still get interference.
Like I mentioned, Do you know if the tv's are running amp's?
Can you walk around with the nano running off a small SLA 12v battery whilst on the phone to the customer to find a suitable location?
20 meters is a fair distance, 10 - 15 meters does the trick for me.
There are two other things I can think of.
dolanp
12-16-2009, 07:50 AM
Ok, we have got to the root of the issue. The VHF TV reception here in Ireland starts at around 175Mhz. The CPU of the Nano is 180Mhz. Even with the power output at pratically zero, it still interfers. Even in station mode with no associations, it still interfers. It seems that the clock speed of the CPU is resonating at a similar frequency of the TV channel and this is then been amplified by the TV antenna and masthead amplifiers thus causing the diagonal interference lines.
What I did was to spray the exterior of the nano with rf shielding paint. The front section was not painted to allow the antenna to perform.
Problem was immediately solved.
Perhaps this might be something to take into account during manufacturing.
sxpert
12-16-2009, 08:05 AM
What I did was to spray the exterior of the nano with rf shielding paint. The front section was not painted to allow the antenna to perform.
Problem was immediately solved.
Perhaps this might be something to take into account during manufacturing.
interesting.
I DID talk about that to ubnt-mike in madrid... (spraying the insides of the case to prevent hf from leaking)
dolanp
12-17-2009, 08:30 AM
interesting.
I DID talk about that to ubnt-mike in madrid... (spraying the insides of the case to prevent hf from leaking)
yes, the RF shielding did the trick. Any devices we have installed,which are known to interfer with TV is getting a lick of paint.
Ah... I see your based in Grenoble. I visited Grenoble a few months ago on my way to Alpe D'huez. I was amazed with the amount of Nano devices installed in the village. The temperature was around -10/-12 and i was still able to connect sucessfully to the nano AP's. Are you involved in the area?
Paul
