Verizon and AT&T To Temporarily Turn Down 5G Power To Address FAA Worries (lightreading.com) 24
AT&T and Verizon said they will slightly reduce the power of their 5G transmissions in C-band spectrum for six months. The companies said they will do so to allow federal aviation officials more time to study how such transmission might affect radio altimeters in aircraft. From a report: "We are committed to the rapid deployment of 5G and the safety of aviation," the two companies told the FCC in a new letter. "While we continue to believe the FCC's current rules provide for both, we will, without waiver of our legal rights associated with our substantial investments in these licenses, adopt these precautionary measures to allow for additional time for continued analysis." Importantly, according to the Wall Street Journal, executives in the wireless industry don't expect the power reduction to "seriously impair" the operators' 5G operations in the spectrum band. Further, the operators continued to argue that their 5G transmissions in C-band spectrum do not pose a risk to air travel in the US, despite a report from some airlines showing a potential risk of interference to aircraft operations.
Uh huh (Score:2)
"We are committed to the rapid deployment of 5G and the safety of aviation,"
The former taking priority over the latter in the boardroom I would imagine. Bonuses are at stake!
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Jesus, did you swallow a ad-agency?
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Jesus, did you swallow a ad-agency?
He probably has a Macrobiome imbalance [xkcd.com] ...
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Moron. All companies have a moral (and legal in most western jurisdictions) obligation to do no harm.
Doesn't sound right (Score:5, Interesting)
At some point during the development of 5G technology, the equipment would have gone through FCC certifications, as well as a whack of testing to check for interference tolerance for accepting interference and causing it for other devices. The FCC would have also assigned and allocated frequency space for 5G to prevent overlap and interference with other signals.
Are you telling me that at no point along the way aviation experts wouldn't have piped up and said "what about aircraft devices?"
Why is this just being questioned now, years after deployment started.
Re:Doesn't sound right (Score:5, Interesting)
The keywords are here: some airlines showing a potential risk of interference
With the recent fuck ups by companies like Boeing, airlines are deathly afraid they might have something else unforeseen on their hands, and just "want to be sure" (read: We dislike uncertainty, even if that uncertainty only exists in our or our customer's heads and has no basis in reality whatsoever).
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This paper here https://www.rtca.org/wp-conten... [rtca.org] seems to suggest it is not only airplane independent, but also applies to helicopters.
Re:Doesn't sound right (Score:5, Informative)
The problem isn't direct overlap -- there is a 220 MHz gap between the upper end of this 5G band (3.98 GHz) and the lower end of the protected aeronautical band (4.2 GHz). It's about out-of-band sensitivity of old radar altimeters, and spurious emissions by 5G equipment.
The existing standard for radar altimeters is 40 years old, and so predates widespread, relatively high-power emitters like cell towers. RAs typically emit at about 1 W (30 dBm), and the received power will be much less because of the distance-squared law and imperfect reflection by the ground. In comparison, AT&T and Verizon agreed to limit their intentional emissions to 62 dBm/MHz -- each MHz of bandwidth using about 2000 times what the RA emits. The RF filters used by RAs aren't designed with high selectivity, so they attenuate out-of-band signals less than one might wish.
Spurious emissions by towers may be worse, because some will be in the RA band, and they would need many 10s of dB of attenuation (relative to the intended emissions) to have smaller amplitude than the RA return.
For more detail, see the RTCA report on the potential for interference: https://www.rtca.org/news/rtca... [rtca.org] .
Re: Doesn't sound right (Score:5, Interesting)
I managed a college radio station or two back in the day, bringing one from 10 to 100 w when they phased out the 10s. FCC has an extensive list of things you need to make sure of to so much as play music, never mind blanketing the terrain in digital signals. Before TV dropped analog, there was a local college station that would bleed harmonics into the adjacent tv channel, which I forgot about once analog went away. Recently picked up an SDR kit, fired up Cubic, and sure enough, almost 20 years later they still show 2 harmonics that come in clear as a bell. The reverse was also true, in Providence RI USA you used to be able to pin your FM dial in the car and listen to the Flinstones playing on Ch 6.
Re: Doesn't sound right (Score:4, Interesting)
"The reverse was also true, in Providence RI USA you used to be able to pin your FM dial in the car and listen to the Flinstones playing on Ch 6."
Don't forget the "radio stations" that got an LPTV license for channel 6 and transmitted color bars as video knowing their FM audio would get picked up by 99.9% of FM tuners on the market.
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The harmonics are a problem that can and should be fixed, although with the current pwn3d state of the FCC, it probably never will be. Picking up Channel 6 on your radio isn't an out-of-band bleed problem though, it's just a radio that can tune slightly out of the normal band. Since it's not transmitting, it's not a problem.
Re:Doesn't sound right (Score:4, Insightful)
Agree! " 220 MHz gap between the upper end of this 5G band (3.98 GHz) and the lower end of the protected aeronautical band (4.2 GHz). It's about out-of-band sensitivity "
It is amazing how many people, politician, decision makers, media don't understand harmonics and think frequency bands are hard and fast like a brick wall. And even worse, think old equipment doesn't exist or should be replaced after 5 years at users expense!
Want to reduce landfill waste, or electronic waste, or global warming? Minimize forced throwing away of 10s of millions of dollars of equipment every year simply due to 'no longer supported', 'interface changed', 'signal space changes'!
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There should be a wealth of data available to settle this quickly. I suppose maybe the issue is that a lot of it comes from other countries, so can't be used.
East Asian countries like Japan and China have very high levels of 5G deployment and aren't seeing aircraft having issues.
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They also don't have the mix of air traffic that the US does.
The US has ADS-B deployed as ground stations - everyone else in the world is using satellites. Why? Because satellites would be overwhlemed with US traffic so they use ground stations to alleviate most of the traffic.
It's not that the US has a lot of commercial flights - they do, but they also have a lot of GA flights. GA outs
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ADS-B is widely used elsewhere, including in Japan and China.
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I mean, it isn't unusual to train in an aircraft over 30 years old.
The Cessna 150 I first trained in for my private was older than I was.
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There isn't that much to go wrong in a light aircraft over 30 years old that hasn't already been replaced. That probably has a lot to do with it.
In the case of pilot replacement, it's not always an upgrade. :)
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Are you telling me that at no point along the way aviation experts wouldn't have piped up and said "what about aircraft devices?"
Aircraft hadn't been vaccinated against COVID at that time, so the 5G interactions weren't fully realized ... :-)
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The issue here is more about the spill noise outside the allocated 5G that can impact the ground radar on the aircraft that have about 1W of transmission power and the reflections are magnitudes weaker. So even a small piece of noise outside the allocated band can disrupt the ground radar.
See a bit more here as well on YouTube: https://www.youtube.com/watch?... [youtube.com]
Doesn't bother me. (Score:5, Funny)
I doubt anyone who cares will be affected. Seriously, I just got my COVID-19 booster shot this week and my 5G reception is better than ever. ;)
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Fake test (Score:2)
This reminds me of one of those fake tests where they prove someone who supposedly can sense something by later telling them it was never turned off.
So my guess is the FAA will immediately come back with information supposedly proving that interference was reduced after the power reduction. Then the cell companies rebuttal that by saying they never changed anything the whole time.
lets see.
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The thing is, the fake tests confirm the theory that people can't sense em radiation from wireless devices. Whereas in this case it is the theory itself which says the measured levels of power output at airports actually do interfere with aircraft. https://www.rtca.org/wp-conten... [rtca.org]