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

[el bandido]

Check out this PDF file for the tuner module, it is a generic model, but the input diagram is the same, the little pyramids on there side are the input and AGC amps inside the tuner.

[Only registered and activated users can see links. ]

It has about 50 dB of variable input gain, this controlled by the RF decoder chip set.

What was available in 1997 might have been a little different. Look at the AVL6261: [Only registered and activated users can see links. ]

[Terryl]

Well that's a de-modulator chip not the tuner module I'm talking about, the tuner is a separate item, it's what the coax from the LNB connects to, then the signal is fed into that device (AVL6261) your looking at.

And the overall design has not changed much in the last decade or two as far as the tuner module block diagram goes.

[el bandido]

The 3400 to 9900 MHz high pass filter from Mouser arrived today. I installed it and immediately noticed all signals on my cell tower went away. I also did a quick check of the 5GHz router. The TinySA Ultra could pick up the 5G signals on the router when it was operating with the high pass filter installed. So the high pass filter seems to work as advertised.

I also had to drive bit today, including part of downtown Atlanta. I let the TinySA Ultra scan 3500-4500 MHz as I drove. Many cell towers were passed along the way. None of the cell towers showed any c band signals until I got within few miles of Atlanta, but even then c band cell signals were few and far between. Cellular c band signals come and go real quick as compared to other bands such as the 1900, 2500 MHz cell bands.

A few screenshots made with the TinySA Ultra are shown below. These screenshots were taken near Lithia Springs Ga., close to Interstate 20. A small vertical antenna was used, and no attempts were made to locate the source of these signals. But apparently, they were coming from a nearby cell tower. Personal time and traffic didn't allow for much signal hunting.

One thing I noticed about these c band cell signals is they act more like router signals. Usually when looking at a cell tower through the analyzer, the signals that are shown are consistent, or at least fairly consistent. The c band cell signals I saw to day would jump up and down in signal strength, and sometimes a small group of the signals would disappear, only to reappear a second or two later. Router signals act similar to this.

C band cell signals near Lithia Springs Ga.:
[Only registered and activated users can see links. ]

[Only registered and activated users can see links. ]

[Only registered and activated users can see links. ]

I may look at these signals again when I have time and need to be in that area. I drove right by a loaded dower near downtown Atlanta that had c band cell signals a lot stronger than what is shown above. How close I was to the actual source of the signals shown above is unknown. There was a lot of clutter (buildings and such) so the tower could not be seen. It is also possible the signals shown above were from a mini cell or something similar. There just wasn't enough time to investigate. Maybe the proper time to investigate will be available another day sometime in the future.

[armadillo_115]

....One thing I noticed about these c band cell signals is they act more like router signals. Usually when looking at a cell tower through the analyzer, the signals that are shown are consistent, or at least fairly consistent. The c band cell signals I saw to day would jump up and down in signal strength, and sometimes a small group of the signals would disappear, only to reappear a second or two later. Router signals act similar to this....

Limited number of users this early in the process. I would guess those signals become more consistent/constant in the future as more users use the spectrum. Probably be a steady buzz in a years time.

Now if you can keep that buzz no closer than Atlanta.... I'll be happy. lol

[el bandido]

C band 5G cell frequencies operate on what is known as Time Division Duplexing or TDD. A Time Division Duplexing (TDD) system will transmit periodically as compared to a FDD system which transmits all the time.
More info on FDD and TDD in the link: [Only registered and activated users can see links. ]

[armadillo_115]

According to that link:
5G FDD - Low frequency bands below 10 GHz
5G TDD - High frequency bands above 10 GHz

[el bandido]

[Only registered and activated users can see links. ]

[el bandido]

A Satmagazine article from May of 2020 in the link directly below does a good job of explaining 5G c band interference
[Only registered and activated users can see links. ]

5G and satellite interference is pretty much a world wide problem. The main difference between North American 5G and the rest of the world 5G is frequencies. This is why you see a lot of filters that work between 3.7 and 4,2 GHz. A 3.7-4.2 GHz filter is not much of a solution for 5G interference in North America.
India Link: [Only registered and activated users can see links. ]

There are also a couple of .pdf files attached to this thread that give a bit more information which may or may not be useful.

Here is a video from a person that does not seem to have a clue what 5G satellite interference is or does. it is included anyway because it is comical. This is a hobby so we should have fun, which the fellow in the video seems to do. I would say though, the idea of all of the satellite channels being moved to satellites between 91w and 107w is not correct.

[Executive]

Hilarious video. "Expert"

[armadillo_115]

Maybe I should start my own C Band series on Youtube.

Take that time I was pushing the tractor with the pickup and it got away from me.. Jumped the log I had laid down and headed down the hill. That ribbon cable risked it's life to save my tractor, jumped up and wrapped around a lower hitch. Almost rolled the tractor, but finally brought it to a screeching halt.

Of course, it yanked the VBox, fta receiver, and Nintendo plumb off the entertainment center and pulled them all the way to the hole in the floor. Turned over the entertainment center and dumped the tv on the floor. Not only did nothing break... but I wound up with several extra feet of ribbon cable .

If I'd only thought to record it... would probably go VIRAL.

Not sure how that incident relates to 5G though.