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

[el bandido]

There have been reports of 5G C band interference in the lower part of the band between 3700-3850 MHz. This portion of the band is supposed to be cleared for the United States, but these lower frequencies are still used by a lot of other countries including Mexico. I imagine that since this portion of the band has been cleared, many people automatically think any anomalies or problems with these frequencies Has To Be C band interference.

This morning I had a problem with a tv channel on 97w. The transponder for the channel is 3780 H with a symbol rate around 6522. The FEC is 5/6, and the transponder is also DVB-S2, 8psk. A quick look at the minimum db lock chart shows I need around 9.5 db to open this channel.

The fta receiver shows I have between 13 and 13.5 db for a signal, which means I should be around 3 db Above the minimum signal amount that is needed tp lock this transponder. So why am I having problems with it this morning?

Here is a screenshot the channel. The top of the picture has artifacts, so it is easy to see a problem.
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The fta receiver shows a nice, solid 13-13.5 db signal for this transponder, but that number is not accurate. The fta receiver shows a smoother average of the signal, and is not accurate enough to show spikes and fluctuations of the signal like an analyzer can. What is really happening is the signal is dropping below the threshold for lock briefly, then the signal returns to a level above lock. This is why the tv picture jerks, has audio stutters, or other display problems.

Here is a screenshot of the analyzer with the transponder frequency tagged. The signal strength shown is -49.91dbm
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Here is another screenshot of the analyzer taken about 1 minute later. The signal strength shown is -50.91dbm
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The noise floor on the fta receiver is -60dbm. Most fta tuner specs are from about -60 to -30 dbm. A few of the TBS cards may have a more generous noise floor down to about -70dbm. But FTA receivers are usually -60 to -30 dbm or thereabouts.

Using -60 as the noise floor, the first screenshot shows a signal of. So the first analyzer screenshot shows a signal about 10db above the noise floor (60−49.91= 10.09). The second analyzer screenshot shows a signal about 9db above the noise floor (60−50.91=9.09) which is below what the receiver needs to lock the transponder.

The TinySA Ultra is not some wildly accurate piece of testing equipment, but it can give good information and show WHY reception problems exist. Watching the analyzer shows the 3780 H transponder signal going up and down several times a minute. The fta receiver shows more of an average signal, and is not designed to show rapid up or down spikes in signal strength.

All that is happening here is the signal is fluctuation, which causes picture problems. Why the 3780 H signal is jumping up and down is unknown. But the analyzer shows a fairly clean signal. If the problem was 5G interference, then we could expect to see on and off signal spikes surrounding the transponder.

Most likely, the same thing would be seen if other transponders that have equal or similar problems on my satellite receiver were carefully checked. We know some users have experienced actual 5G interference in c band. But it seems now the blame for any little reception problem is 5G.

[Terryl]

The best way to check for data loss (the picture breaking up due to loss of data bits in the data stream) is with a BER* generator/decoder setup, unfortunately we don't have a way to send a true BER free signal up to the satellite.

When the BER gets too high the FEC* cant fix the loss of data for that decoded byte (or bytes) of signal, then you start getting pixulation or total loss of lines of code

We use to setup on the bench the transmitter, receiver and antennas for a true BER check at low input signals, also with a harmonics generator and co-channel generator, injecting a BER free modulation (zero BER on the receiver) at the transmitter you can then see how the affect of interfering signals can give you a problem when you reach the limit of your FEC.

*BER= Bit Error Rate, the loss of data bits in a digital data stream.
*FEC= Forward Error Correction, used to correct a data stream with missing data bits.

One other thing is the fact that the 5G signals could also be coming from someone using a 5G phone close by, if your in a large city or town then this could be a possibility.

I live out in the boonies, I have a new AT&T cell tower about a mile away, I can just see the top of the tower, I know it has 5G on it as I now use a Netgear hotspot for internet, this device reports it's connection type, it is getting a 5G signal to and from that tower, I also checked my signals, I don't see any problems with them, (I have no way to look at them like El Bandido) the hotspot is located about 35 feet from the receiver and about 150 feet from the dish, and would be about 30 degrees of to the side of my BUD if I'm looking at satellites further East then 97W.

[armadillo_115]

I live out in the boonies, I have a new AT&T cell tower about a mile away, I can just see the top of the tower, I know it has 5G on it as I now use a Netgear hotspot for internet, this device reports it's connection type, it is getting a 5G signal to and from that tower, I also checked my signals, I don't see any problems with them, (I have no way to look at them like El Bandido) the hotspot is located about 35 feet from the receiver and about 150 feet from the dish, and would be about 30 degrees of to the side of my BUD if I'm looking at satellites further East then 97W.

But is the 5G you are receiving operating on the C Band Frequencies? Which would be Band 77.

Below quoted from a website updated September 3, 2022:

While AT&T won the 39GHz spectrum in May 2020, it’s still relying on its old 850MHz frequency band to offer low-band 5G to users in the US. The average 5G speed of AT&T mobile network currently is 59.3Mbps. According to a report, AT&T has launched 39GHz 5G in parts of Milwaukee, Wisconsin. It’s expected that AT&T’s 39GHz 5G will offer speed up to 3Gbps.
Band Frequency Band Type
n260 39GHz mmWave
n5 850MHz Low-band
n77 3.7GHz Mid-band sub-6 GHz
.................................................. .................................................. ........

mmwave only has a range of like 2 city blocks!
Mid-band (like n77) range is much further.

Edited: Sorry, I misidentified mmwave range for Mid-band range. Corrected above.

[armadillo_115]

Also found this: Published Feb 15th, 2022
<quote>
Technically, Mid-Band frequencies are still “Sub-6GHz,” but AT&T is specifically deploying its Mid-Band networks separately to its low-band networks. After months of delays, AT&T has finally deployed its mid-band network — but only in some cities. Mid-band 5G is considered the key to unlocking the dreams of 5G, thanks to the fact that it can cover larger geographic areas with fast connectivity. The cities where AT&T C-Band 5G can be found are below.
Dallas/Fort Worth
Houston
Austin
Chicago
Detroit
Jacksonville
Orlando
Miami
<end quote>

Those mid-bands are what will ruin our C Band Dish world. But may be a long time coming to the boonies... if ever.

[el bandido]

I have been looking for a device that would cost less and produce similar information as the TinySA Ultra. A software defined dongle seemed interesting so I decided to try one out for about $30.00 in cost. The software defined dongle (sdr) that I chose is nothing more than a modified DVB-T usb tuner. Here is the identification as seen using the "lsusb" command: Bus 002 Device 005: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T.

SDR devices usually only work to around 1.7-2 GHz, which is way short of satellite c band frequencies. But most c band lnbs used in North America convert down to 950-1450 MHz or thereabouts which would possibly make the DVB-T sdr dongle useful for looking at signals through the lnb. Free computer interfaces can be found, but none of them that I have seen have enough frequency coverage to be useful in detecting c band interference.

A DVB-T tuner is designed to cover a few MHz which probably limits its capabilities as a wide band scanner. The sdr interferes that I found only show a few MHz in range, but we really need something capable of showing at least several hundred MHz of range in order to be useful for identifying or locating c band interference. Shown below are some screenshots of a sdr interface using DVB-T sdr dongle and the TinySA Ultra for comparison.

A satellite transponder is too large to be shown on the sdr interface, so I used a satellite beacon as an example.

Here is the sdr interface showing a satellite beacon. Note that only a couple of MHz in spectrum can be shown:
[Only registered and activated users can see links. ]

Here is the TinySA Ultra showing the same satellite beacon, and also showing the entire range fo frequencies for the lnb:
[Only registered and activated users can see links. ]

This particular Software Defined Radio setup will be useless for c band interference checks because it does not have enough range. We need to see at least 100 MHz, preferably 2-300 MHz when searching for c band interference. So the software defined radio setup shown above is not going to work unless some major changes can be made.

I purchased PLZ‑SA354400B analyzer that cost roughly half the price of the TinySA Ultra. Shipping time for this device is estimated at two weeks. You can only do so much with cheap stuff. The TinySA Ultra is useful for finding c band interference, and is also useful for other things related to satellite tv. But I would like to find something that has similar capabilities that costs less money. We will see....

[Terryl]

Try a program called "SDR Console" it has a lot more options as far as bandwidth and filters.

And take a look at this hummer, it says it covers out to 2 GHz, [Only registered and activated users can see links. ]

[el bandido]

I don't see SDR Console covering over a few MHz. Any ideas on how to make it display a 50 - 100 MHz spread?

That SDR Software Defined Radio Receiver looks nice. I am not interested in buying anything else right now. Maybe you or someone else will try it???

[LNB-ZHAO]

Very meaningful discussion and sharing, testing is serious. LNB has been designed by me for 20 years, and it is certain that 5G communication will interfere with C-band TVRO. Now it is mainly because too many fake products have misled the market and consumers. Too many Passive filters and LNB in the market are not capable of fully resisting 5G interference. If the protection belt is only 20MHZ in the future, Passive filter and WR229 LNB must be adopted (when you need to receive horizontal polarization and vertical polarization, you also need OMT). 5G frequency interference with TVRO system will lead to a large number of intermodulation of LNB products, so that STB cannot modulate and demodulate. We have the product technology, but we don't have loyal customers. 5G interference with home TVRO and FSS will be more obvious in the future

[LNB-ZHAO]

I want to give a comprehensive explanation of LNB recently, especially for the interference of 5G communication frequency and C-BAND TVRO, and really explain the work of LNB in 5G frequency. With the gradual opening of 5G mobile communication, how to select truly effective LNB, especially for LNB NOISE, REJECTION, P1DB, Rejection. There are too many false product publicity in the market, which is poison to consumers. Most LNBS in the market, including many well-known brands, have false publicity. I will explain and show them in the future, and observe them through signal source interference test and spectrum analyzer test. The false hype has slowed the development of 5G, while affecting satellite TVRO's home entertainment.

[armadillo_115]

Interesting to see where this is headed.