5G interference, new LNB?

aceb

aceb

Specialist Contributor
My Satellite Setup
TBS 6925
1.8m Precision + PLL Bullseye, motorised but probably siezed now.
2 x Sky Zone 2 for 28/19/13°E
My Location
Sussex
I used my C-Band system today for the first time in over a year to be greeted with not much at all. Having swapped out the LNB, coax and changed the sat card I'm assuming these nasty big spikes are 5G from one of the nearby masts. They seem to be doing a good job of affecting all of C Band with even strong signals from 20E being pixelated and the SNR jumping all over the place.

So, either it's a new LNBf that's filtered and starts at 3.7GHz or I just remove the 1.8 and be done with it.

Are there any recommendations for an LNB or is this kind of signal just too much to cope with?


20.0E-RFScan.webp
 
see my thread here - might help

Just Sharing This - My Channel Master 1.8 project.

I preferred the T plate to the AVcom for overall results on my offset 1.8 and 2.4 dishes..... not the case on the prime focus Prodelin though ... could not make a plate to perform as well as the AV - Com on that dish !
www.satellites.co.uk www.satellites.co.uk
 
I don't have any C band installed at the moment but checked out the levels using an analyser with a 2dB NF LNA and a wide band horn (~7dB gain). The peak level, corrected for the LNA, was about -35dBm. It may be a fair bit higher as I was only looking in 300kHz & 1MHz BW and the signals are wider than that, all are pulsed. The frequency range of most of them was similar to your's, @aceb (3.58-3.68GHz). The frequency spectrum shows max hold as blue and live as black. The time domain plot shows the pulse characteristics. I don't know how far I am from the sources of these signals but it is at least 3 miles.

3.6GHz_5G-2.gif 3608MHz_5G_Time.gif

Given ~60dB gain in an LNB, the level I was seeing will overload and cause blocking across the whole range. @aceb's CS scan shows >0dBm out of the LNB which may be close to limiting. I don't know the C138 LNB but if the filter is the same as the other Tit ones, it is not particularly sharp and after the LNA so might not do enough. It's well worth a try though.

If money were no object, this is the kind of thing to use: C-Band Extreme Bandpass Filter
 
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I would go with a new LNB, one with a 5G filter built in, as most of the add on filters I see are for the commercial end users, and very very expensive.
 
Thanks @Manikm909, an interesting long thread! I'll pour a glass and read through it but at least my suspicisions are confirmed about 5G and there is a potential cure.

​

 
The best lnb against C-band interference is an antenna of at least 2.20m!!!
In my case, it's true, with a smaller antenna-1.50m, the Titanim PLL didn't really help against interference. Also, I used a special lnb for 5G, Mediastar 5G, which reduced a bit of interference.
I didn't notice much difference between these anti-interference lnbs and a regular lnb, like the Galaxy Innovations
At 20.0E I tested all three lnbs and the Titanium makes almost no difference.
 

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@satesco , thanks for the grabs, so you used the original C1W-PLL? I guess we need to see a similar chart comparing the C1W against the C138 or the C138 against the Mediastar or Galaxy?

Not sure what path to take at the moment, for the amount of C Band viewing I do I'm not sure I want take the chance with the C138 so it might be time to move the 1.8 Precision on, I'll mull it over.
 
The Titanium I used is model C1W-PLL and not C138. Perhaps the latter is better for interference. The next step is for whoever has it to give us pictures/screenshots if and to what extent it meets our expectations. But I'm not sure it will help those who want to lock the signal below 3800 MHz, where there are a lot of transponders with satellite TV programs in the C band. I hope I'm not right for those who buy the Titanium C138.
I have used several anti-jamming lnbs, the amateur ones, and I have to say that none can protect except on certain frequencies, and not completely.
On satellites with strong signals, reception is possible even below 3700 MHz. For example, at 40.0E, the satellite has such a strong signal in my area that interference is hardly noticeable on a few transponders.
Here are the three lnbs mentioned in the previous post, with the depolarizing plate I made.
 

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aceb said:
Not sure what path to take at the moment, for the amount of C Band viewing I do I'm not sure I want take the chance with the C138 so it might be time to move the 1.8 Precision on, I'll mull it over.
Click to expand...


If you decide to move it on I hope it gets a good home, it has given great service to its owners over a few decades.
I remember the day you collected it from me and loaded it on to the roof of your car.

If I remember correctly, the original owner bought it brand new in the late 1980's as a retirement gift to himself? I was the 2nd owner.
I can't remember if there was a small plate on the back indicating the date of manufacture?
The original for sale topic where I listed it is probably still on the forum with pics?

As an aside, I still have your Precision vinyl logo here ready to go onto the dish.
If you send me an address by PM I will get it in the post if you still want it?
 
satesco said:
The best lnb against C-band interference is an antenna of at least 2.20m!!!
Click to expand...

I just want to let the community know that if positioned in the proximity of 5G transmitters, no filters help whatsoever, no matter the dish size. Note my 3.4m PFA antenna.
For the last year or so I've hoped to have just occasional problems in the range up to 3.7 GHz, but in the last couple of months unfortunately the three operators extensively filled the gap all the way up to 3.8 GHz.
I have totally distorted reception from any given position, MCPCs are practically useless, some SCPCs still get through without any major disturbances but those are rather rare.
Here attached spectrums from East to West, note all the spikes in 3.6 GHz - 3.8 GHz.

83E.png765E.png685E.png62E.png10E.png5E.png3E.png8W.png18W.png405W.png
 
Thanks. Interesting
 
Satfaca said:
I just want to let the community know that if positioned in the proximity of 5G transmitters, no filters help whatsoever, no matter the dish size. Note my 3.4m PFA antenna.
For the last year or so I've hoped to have just occasional problems in the range up to 3.7 GHz, but in the last couple of months unfortunately the three operators extensively filled the gap all the way up to 3.8 GHz.
I have totally distorted reception from any given position, MCPCs are practically useless, some SCPCs still get through without any major disturbances but those are rather rare.
Here attached spectrums from East to West, note all the spikes in 3.6 GHz - 3.8 GHz.

View attachment 145710View attachment 145711View attachment 145712View attachment 145713View attachment 145714View attachment 145715View attachment 145716View attachment 145717View attachment 145718View attachment 145719
Click to expand...

Luckily for me at the moment the nearby 5G towers spewing out interference are still just under 3.7GHz but as you say, if you live within spitting distance then you are screwed. My AliExpress outboard 5G filter did give me a little protection though.
 
Well one way to fix this is to use a solid dish, as a mesh dish (if your using one) does not have very good side/back rejection, we have used dish skirts on solid dishes to (try and) stop side interference, but if the 5G towers are out in front of the dish your toast.

And an LNB with a tuned cavity filter is very expensive.

Note: You have a spectrum analizer, can you look at the 5G signals to see if there may be any inter-mod?? (frequency- A +Frequency- B = Frequency X, the unwanted one) If so then it could cause your problems and a complant to your RF frequency regulator may be useful.
 
Unfortunately no way to fix this, I see all three transmitters with clear sight, closest some 400m to the south, the other two 800m & 1200m to the west, using solid Prodelin dish. So, 5G is the exterminator of C-band satellite reception.:(
 
Yup, no way to fix that except a pin in someones coax....(no I did say that)
 
Satfaca said:
I just want to let the community know that if positioned in the proximity of 5G transmitters, no filters help whatsoever, no matter the dish size. Note my 3.4m PFA antenna.
For the last year or so I've hoped to have just occasional problems in the range up to 3.7 GHz, but in the last couple of months unfortunately the three operators extensively filled the gap all the way up to 3.8 GHz.
I have totally distorted reception from any given position, MCPCs are practically useless, some SCPCs still get through without any major disturbances but those are rather rare.
Here attached spectrums from East to West, note all the spikes in 3.6 GHz - 3.8 GHz.

View attachment 145710View attachment 145711View attachment 145712View attachment 145713View attachment 145714View attachment 145715View attachment 145716View attachment 145717View attachment 145718View attachment 145719
Click to expand...
Which is why there was compensation into the $m ( and paid out) when it was announced.
 
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oh so we can all get compensation? result...
 
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