Another reason to ban 5G?

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#2841753 2-Jan-2022 10:00

gzt: Probably true it should have been sorted out years ago. Imo this is the airlines and air manufacturers playing chicken with the government. The FCC has a responsibility to prevent interference but it's not unlimited. At some point the airlines and air manufacturers will need to install better receivers and signal processing. Probably the airlines and Boeing Airbus etc would like to postpone that until the next generation of aircraft.

But 5G successfully used in 40 other countries with only a 100MHZ guardband.

Ge0rge

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#2841806 2-Jan-2022 10:09

ajw: But 5G successfully used in 40 other countries with only a 100MHZ guardband.

Mate, while that is a valid point - we heard you the first six times. There have also been some valid reasons posted as to why there have been no issues reported as well - and while hearing different views makes this and other conversations on this site that much more interesting, repeating the same thing doesn't really add any value.

gzt

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#2841811 2-Jan-2022 10:32

As I understand it Japan already uses the same C-band channel as planned for USA phones. You would think it would happen there if anywhere.

Technofreak

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#2842050 2-Jan-2022 19:41

gzt: Probably true it should have been sorted out years ago. Imo this is the airlines and air manufacturers playing chicken with the government. The FCC has a responsibility to prevent interference but it's not unlimited. At some point the airlines and air manufacturers will need to install better receivers and signal processing. Probably the airlines and Boeing Airbus etc would like to postpone that until the next generation of aircraft.

There's probably an element of truth in this. The development and certification takes time and is costly. There are a lot of incentives to keep using something if it's already approved and working. Plus this sort of gear can expect to be in use for 20 to 30 years. Airlines and aircraft owners don't have the money to throw out and replace serviceable equipment that isn't end of life.

Better receivers will be installed in new aircraft or when a device is beyond economic repair, it's the already installed non BER equipment that's the problem. Who pays to replace that?

Edited to add.

Radar altimeters are a bit like an octopus with respect to aircraft systems. They have tentacles that reach into other systems. It's probably not as simple as just replacing the Rad Alt. Other impacted systems may need updating too.

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Beccara

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#2842105 2-Jan-2022 20:28

Anytime Boeing and Airbus agree on something you should sit up and listen, It looks like the issue is fairly specific and given the US airlines are asking talking about injunctions around 135 locations it seems there is some legitimate issues. Whilst other countries are reporting operations OK with C-Band/3ghz nobody so far has said if this is with or without concessions from mobile operators and airports. The below report indicates that this is legitimate concern that warrants caution. There is little public tolerance for aircraft delays/cancelations/crashes

https://www.mondaq.com/canada/technology/1041382/losing-connections-5g-wireless-technology-and-the-potential-risk-for-aviation

The results of the RTCA's testing and evaluation, and contained in its peer-reviewed publication, reveal "a major risk that 5G telecommunication systems in the 3.7-3.98 GHz band will cause harmful interference to radar altimeters on all types of civil aircraft – including commercial transport airplanes; business, regional, and general aviation airplanes; and both transport and general aviation helicopters."4 The 5G interference could result in inaccurate altimeter readings, or complete altimeter failure, resulting in pilots being unaware of their distance from the ground.

It's worth noting as well that C-Band is a big bloody chunk of mhz, The EU deployment of 5g C-Band? 400mhz away

https://strandconsult.dk/blog/5g-is-suddenly-a-flight-safety-concern-amid-rapid-network-roll-out-in-the-us-strand-consult-investigates-with-leading-eu-spectrum-and-public-safety-communications-expert/

In Europe, the C-band spectrum has been auctioned for 5G, and the implementation is underway. No reports to date have indicated that 5G interferes with aviation. Indeed altimeters operate in the band 4200 – 4400 MHz, almost 400 MHz away from the top end of the applied 5G C-band. However, the US concerns have crossed the pond.

This wouldn't be the first time that the US's chosen frequencies are somewhat globally "unique"

Most problems are the result of previous solutions...

All comment's I make are my own personal opinion and do not in any way, shape or form reflect the views of current or former employers unless specifically stated

ajw

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#2842373 3-Jan-2022 10:03

Verizon wireless and AT&T reject request from FAA to delay C band switch on. The wireless companies in a joint letter on Sunday said they would not deploy 5G around airports for six months but rejected any broader limitation on using C-Band spectrum.

https://www.reuters.com/business/media-telecom/att-verizon-ceos-reject-us-request-5g-deployment-delay-2022-01-02/

Technofreak

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#2842399 3-Jan-2022 11:24

You can expect to see more court action. Seems to me that AT&T and Verizon are letting profit get ahead of safety.

The fact that there's restrictions in France and their 5G frequencies are further away from the Rad Alt frequencies and use a lower max power is surely reason for caution in the US.

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ajw

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#2843141 4-Jan-2022 17:40

AT&T and Verizon agree to a two week extension before C band gets switched on.

https://www.marketwatch.com/story/at-t-verizon-agree-to-delay-5g-rollout-for-2-weeks-11641265815

Technofreak

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#2843989 5-Jan-2022 21:39

As mentioned in an other post

https://www.avweb.com/aviation-news/prize-fight-between-telecom-and-airlines-put-back-on-hold/

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ajw

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#2856120 25-Jan-2022 14:51

Wish the FAA would make up there minds.

https://arstechnica.com/tech-policy/2022/01/airline-ceos-make-u-turn-now-say-5g-isnt-a-big-problem-for-altimeters/

frankv

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#2856589 26-Jan-2022 12:42

So, in theory C-band 5G could interfere with "poorly designed" radar altimeters. But no-one actually got round to checking whether any poorly designed radar altimeters were in use. And it turns out that all the ones they did check are OK. Including Boeing 717s which were manufactured in 1998-2006, so I guess whatever brand of radar altimeter Boeing uses has been "well designed" for at least 15 and perhaps 24 years. And you would have to expect that the same would apply to Airbus and the smaller aircraft manufacturers.

If you think about how a radar altimeter works, it would be getting all kinds of reflections as it flew over buildings, and it would need to filter out the spurious reflections effectively just to be functional. So effective filtering of out-of-band radio waves would need to be part of the design anyway.

Perhaps this will also mean that "airplane mode" on cellphones will become a thing of the past?

tieke

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#2856630 26-Jan-2022 13:33

I thought the comment by jucadrp in this reddit thread was quite informative:

"Your airplane is equipped with a radar altimeter that operates between 4200 and 4400 MHZ.

The 5G towers are equipped with transmitters that operate between 3700 and 3980 MHZ.

The main problem reside here: The filter that your airplane use is a many decade old design that causes a big problem:

Check this out for ease of understanding: https://www.5gtechnologyworld.com/wp-content/uploads/2021/12/5G_Spurious_emissions_1459x550.jpg

You see, even though we left a WHOPPING 220MHZ separation (We called it BAND GUARD - mark this name for later) between 5G and Radio Altimeters, the filters used in the aviation industry will filter only frequencies bellow the green dotted line. The better the filter design / technology, the tighter is around the specific range.

In order words; Your airplane opens a channel too wide to "listen" to your radar and will end up "listening" to the 5G. That was not a problem when only radar altimeters where operating in a 1000s of mhz vicinity, but guess what, spectrum is a limited commodity, not infinite, and it was going to be a matter of time before that space was going to be occupied.

To put in perspective, the CBand have 280MHZ (3980 - 3700). It's shared by at least 3 big carries, and they can all coexist inside the 280MHZ with BAND GUARDs between carriers of only 10MHZ. And we are transmitting from the same tower, antennas some times centimeters apart, without ANY issues with interference.

You know why? Because we use decent, modern FILTERS. Modern filters that should be equipped inn all airplanes by now, since the 5G standards are out for more than a decade already.

The aviation industry had time to retrofit their airplanes. And now they are, sorry to be blunt, playing dumb. They know they can hold the nations hostage by saying that this will disrupt flights in the middle of a pandemic, and gather support from the populace.

Obviously safety is paramount so I'm not advocating to turn on and let hell break lose. However, we need to remember: carriers paid many, many billions (81 to be exact) for these frequencies because they were NOT supposed to be in use, in other words, exclusive use.

The aviation industry is basically arguing they want to take over more than they are allocated to (4200 to 4400) to operate their altimeters. This is not fair with the carriers, and ultimately, to their costumers and shareholders, which will bear the blunt of the cost of these billions of dollars invested that they can't use when they've planned."

ajw

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#2856641 26-Jan-2022 13:43

@tieke

The $US85 billion does not include the extra millions they have spent on C Band equipment to be installed on cellsites and the extra rent payable to the tower leasing companies.

empacher48

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#2856648 26-Jan-2022 14:00

tieke:

You know why? Because we use decent, modern FILTERS. Modern filters that should be equipped inn all airplanes by now, since the 5G standards are out for more than a decade already.

The aviation industry had time to retrofit their airplanes. And now they are, sorry to be blunt, playing dumb. They know they can hold the nations hostage by saying that this will disrupt flights in the middle of a pandemic, and gather support from the populace.

Obviously safety is paramount so I'm not advocating to turn on and let hell break lose. However, we need to remember: carriers paid many, many billions (81 to be exact) for these frequencies because they were NOT supposed to be in use, in other words, exclusive use.

The aviation industry is basically arguing they want to take over more than they are allocated to (4200 to 4400) to operate their altimeters. This is not fair with the carriers, and ultimately, to their costumers and shareholders, which will bear the blunt of the cost of these billions of dollars invested that they can't use when they've planned."

Perhaps there is an oversimplification of the certification system for updating hardware on an aircraft. It is not as simple as "just bolting on a new filter and off you go". It must be tested to prove there is no issues and those tests will go well beyond what is considered normal or even abnormal operation.

Such an item would be considered in the aviation system as a significant change to the operating environment of the device and would require appropriate testing. As an example of this, We are rolling out what would seem to be a minor change to the Flight Management Computers, one which puts a note for the autobrake setting onto the FMA and also provides a green number beside the bouncing ball on the altitude scale showing your deviation from the ideal profile. This has been a 7 year project by Airbus to design, test and approve this change.

Since the change was for something on the display, but being integrated into the FMC means that it has to be designed, and tested to prove that the software code hasn't changed anything more significant, that its operating correctly and that when it fails, it fails safe. It must also prove that the change hasn't created any issues with the FMC or its integration with the FAC, ELAC, SLCC, LGICU or the other twenty three different independent systems that rely on the information from the FMC.

As the radar altitude information is not only used as radio altitude information, but the same information is used in TCAS, FAC, FMC and EGPWS (off the top of my head), placing a "tighter filter" on this may cause issues that weren't foreseen in design, but you won't know until it is tested appropriately.

Beccara

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#2856657 26-Jan-2022 14:11

Aviation safety regulations are written in blood. It's good that its been tested, hopefully tested on some aged parts too as filters can degrade. It would also be good to keep the exclusion zones up around airports

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