How To Look For & Find 5G Interference in C Band

[el bandido]

More parts have been purchased that should allow the TinySA analyzer to "see" the signals coming directly from the c band lnb. This will be little bit more messy because the analyzer will read the frequencies that the lnb has down-converted. These frequencies will be in the 950-2150 MHz range for my lnb. The frequencies will have to be read from the analyzer, then calculated using the lnb l.o. frequency. This is no big deal, but it is not as easy as reading what the analyzer displays.

I think it was assumed that the frequencies between 3.8 to about 4.0 GHz would not be used until the end of 2023. Apparently this is not the case for my neighborhood, or the TinySA Ultra doesn't know what frequency it is displaying. All of the other frequencies on the TinySA have been found where they would expect to be found, So I am fairly certain that the 3.8-3.9 GHz frequencies the TinySA shows coming from the cell tower are correct.

It would not do any good to purchase a Titanium C138 LNBF which specifically is designed to filter out 3.5 to 3.8 GHz when the interference is above 3.8 GHz. This may explain why some have purchased this lnb and had it solve their reception issues. But others have purchased it and still have the interference or reception issue. If you don't have any way of checking the frequencies, then you have no way of knowing if the parts you purchased are the parts you need!

[mememeth]

new final tinysa ultra by david, [Only registered and activated users can see links. ]

[armadillo_115]

Excellent idea Mememeth! I have no c band reception issues at the present time.

A map shows T-Mobile Did Not buy any satellite c band spectrum for my area. Also, my T-Mobile gateway does not support c band operations.

Shown below is a scan using a vertical antenna outside. The scan shown earlier was connected to an antenna mounted on the tower and aimed at the cell tower. This explains the big difference in signal strength.

In the photo below, you will set three sets of spikes. The set to the far left is the 600-900 MHz frequencies that are on the cell tower. These are the tallest spikes and also the strongest. The middle set of spikes is the cell bands around 1900-2500 MHz or 1.9-2.5 GHz. The set of spikes to the far right is satellite c band signals on the cell tower that are around 3900 MHz according to this analyzer. It should be noted that the c band cell signals are about as strong as the 1900-2500 signals, but are not as strong as the 600-900 MHz cell signals.

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Elbandido, is it possible to narrow the band range on your TinySA so as to see more detail on those 3900mhz signals?

Curious to see how wide spread the interference would be if the signals were actually entering into your C Band equipment.
Thanks.

[el bandido]

You can narrow the band range down as much as you want.

The next step will be looking into the lnb and see what kind of signals ARE entering the lnb. Just waiting on the proper parts to do this...

[el bandido]

5G C band interference parts Are Not Refundable!

This means if you buy lnb's or other parts such as filters, there will be no refund if the parts do not solve the interference! Below is One example.

From Titanium Satellite website:
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We accept and refund for new and unused or tested defective LNBFs. Our product is not intended to be used as a trouble shooting or system testing device that is returned after testing. We will not refund if our bench testing indicates that a returned product, with defective claim is functioning as designed. When a returned LNBF is tested on our bench and determined to be operating within specification, the buyer is responsible for all inbound and outbound return shipping and handling costs. Returns requests and refunds will only be processed directly from Titanium Satellite. Tested items can be reclaimed within 30 days after we email the results status notification. Unclaimed products will be considered abandoned and may be disposed of after 30 days.

I cannot blame them for doing this. Once you install the parts, they are used and are no longer new. It's that simple. It would be nice if some sort of a test kit could be rented, where you pay only for the parts you need. Doubt that happens though. Unless you want to take chances or gamble, understand what you need and why before you buy any interference parts.

[el bandido]

Basically what happens is your noise floor gets raised when a c band satellite dish gets interference from cellular 5G C band frequencies. Most of our satellite services are in DVB-S or DVB-S2 format. 5G c band cellular is neither DVB-S or DVB-S2, so you could say our fta receivers see the 5G C band cellular as noise.

So let's say your noise floor on your c band dish antenna looks something like this Without 5G c band cellular signals:
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We could give this as an example of what the noise floor looks like on the same c band dish With 5G c band cellular signals:
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The job of the 5G C band interference filter is to return the noise floor to a level that is usable. Really nothing more than that. Some of the unwanted noise may be filtered out using electronics (5G C band interference lnbs) and or mechanical signal filters.

A mechanical interference filter more or less puts up a barrier where the wanted signals can get in, and the unwanted signals cannot get in (rejected). A good mechanical filter for c band satellite microwave will cost money, but it is very efficient at its job.

As for narrowing the signal down on the TinySA Ultra, the second picture shown above was taken using a range of 3.9 GHz to 3.95 GHz coming from my local cell tower using a gain antenna. You may adjust the range up or down to suit your needs.

[el bandido]

I now have the proper connectors to connect the TinySA analyzer directly to the lnb. Now I have an idea an idea of what signals the fta satellite receiver "sees".

Note: Protect the analyzer from any voltage that may come form the lnb. Failure to do this will result in a dead analyzer!

The signals around 3900 MHz that appear to be coming from the local cell tower bother me a little bit. I wanted to see how much interference my satellite dish is getting with these signals. The first thing to do was get an idea of what signals are currently coming from the cell tower and some idea of signal strength.

For this test, we will use 3.9365 GHz (3936.5 MHZ)
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Next, The analyzer is connected to the satellite lnb, The dish was moved to 87w which is almost aimed directly at the cell tower. My lnb has a l.o. of 5750 MHz, and and a frequency range of about 1.2 GHz. This makes my line frequencies roughly 950-2150.

To see what is on 87w, I set the analyzer to scan 950-2150 MHz.
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We are looking for 3936.5 MHZ or something real close to it. So we have: 5750-3936 = 1814.
Look closely at the above picture and you will see 1.8132GHz (1813.2 MHZ) in the top left hand corner. This frequency is also marked with a symbol above the top of it for identification.

Next question would be: "Is this a cell tower frequency on the satellite dish?". To answer this, we move the dish a couple of degrees and see what happens.
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Moving the dish roughly two degrees puts the possible cell tower frequency down in the noise floor. I don't have anything to worry about right now.


The last question would be: " Is a signal with a frequency of 3936.5 MHZ really coming from the cell tower? I can't 100% answer that question, but the analyzer seems to think so. Several cell towers have been tested in my area with this analyzer, and all of them show roughly the same group of 3.8 - 3.9 GHz signals coming from the cell tower. These towers are not in an area that has licensed earth stations or large commercial c band dishes. So I assume the analyzer is reading correctly.

[el bandido]

There is a transponder on 105w that has a frequency around 3712 MHz, vertical polarization. This transponder contains one tv channel, and has been suspected of having 5G interference, which may or may not be true. At any rate, sometimes this channel will play fine for me, but other times it will pixelate and have artifacts that make it UN-watchable.

The analyzer works the same as scanning a satellite: You can only scan one polarity at a time, and both polarities need to be scanned in order to "see" everything. For the analyzer, I select a horizontal or vertical transponder using the receiver's remote then let the analyzer scan. Then I repeat for the opposite polarity.

A vertical scan of 105w shows the 3712 transponder almost all the way to the right of the screen sitting by itself.
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One thing I notice about this transponder is it has a shorter spike than the rest of the transponders to the left on the vertical side of this satellite. Another thing to notice is the 3712 transponder is sitting pretty much by itself. You would expect to have signal spikes all around it or even above it if this transponder was getting 5G c band interference.


So I conclude that my problems with the channel on 3712 MHz are not due to cellular c band interference, But it does have problems. Shown below is a screencap of the channel with interference. Not shown but also happening is the signal will jump from around 15 db to around 10db (snr). The picture also freezes at times.

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[armadillo_115]

Warning!!! The following is speculation.
Is this possible?

With the TinySA setup parallel to a receiver as described previously. (Or better to use a power inserter instead of a receiver?)
Insert a splitter between the multi-switch and dish so that BOTH the H and V lnb's are powered. Then the TinySA could scan both polarities at once.

Or would something go boom?
Geese fly north for the winter. Cats and dogs start shacking up together. Sun rise in the West. Universe collapse into a black hole.

[el bandido]

At minimum, you would be trying to combine two antennas without using anything to properly combine them. We want to get an idea of what signals the receiver is having to deal with. Combining both polarities might give an idea as to what is on the satellite, but it would not help to understand what the receiver sees because the fta receiver is not designed to receive both polarities at the same time.

True cell tower interference may be seen on both polarities of the lnb. The reason for this is cell tower signals are designed to work whether the cell phone or cellular device is facing up, down, or sideways.

I have also seen the idea of using a lnb to hunt for 5G cellular signals. Some seem to think there is something magical about the lnb that allows it to amplify signals. The only signals the lnb can amplify by itself are the line frequencies. The lnb gets its signal amplification from the satellite dish. The lnb antenna is only a single dipole( or a dual dipole if the lnb is dual polarity).