FAA says 5G could impact radio altimeters on most Boeing 737s

Re:FAA says 5G could impact radio altimeters on most Boeing ... by darksaints on Wednesday February 23, 2022 @07:58PM (#30448981)

If this were even remotely accurate, the s-band radars that are commonplace for weather radar and maritime radars would be rendered useless by high power telecom/TV BRS and EBS spectrum.

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Re:FAA says 5G could impact radio altimeters on most Boeing ... by mirashii on Wednesday February 23, 2022 @08:14PM (#30449115)

This is a pretty shallow dismissal that doesn't actually provide data to back up the claim. Why would the interference be substantial enough to make them useless? Which weather and maritime radar? There are many at many different bands. What is the meaningful impact of interference on those measurements, and how does it differ from the impact of interference on radio altimeters used in planes during take-off and landing? These are just a few of the reasonable questions that should be answered in such a strong dismissal. Instead, you called it inaccurate without providing any real analysis.

RFI is a problem in these spaces [1]. It's been a problem for many years, and is an increasing one.

[1] https://www.researchgate.net/publication/283760070_The_Threa...

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Re:FAA says 5G could impact radio altimeters on most Boeing ... by darksaints on Wednesday February 23, 2022 @08:28PM (#30449202)

I already said s-band (which is 2-4ghz) specifically. BRS/EBS (2.5-2.7ghz) has no meaningful guard band to protect s-band radar, and the radars, at least when used on military vessels, are actually dramatically more sensitive than aviation radar altimeters. And not only has EBS/BRS been operating for decades without any problems, but a) the maritime radar emission/detection patterns are horizontal, just like telecom/television, which should produce more interference than the perpendicular patterns of radar altimeters, and b) EBS has operated for 3 decades using television broadcast power levels...1000s of watts as opposed to the 100s of watts that telecom uses. If interference was actually a problem, the DoD would have shut down those two bands back in the 80s.

Franky speaking, everybody here is talking out of their asses, and just rehashing bullshit that they get told. I'll lowbrow dismissal that all day long because it doesn't deserve and inch more of effort.

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Re:FAA says 5G could impact radio altimeters on most Boeing ... by amirhirsch on Wednesday February 23, 2022 @11:44PM (#30450375)

> Frankly …

This whole discussion has a really low SNR

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Re:FAA says 5G could impact radio altimeters on most Boeing ... by anfilt on Wednesday February 23, 2022 @08:45PM (#30449286)

I did not say it was impossible to design a radar system to work with a higher noise floor. Also, if you have looked some of the concerns the FCC has in the S-Band range is radar. If you have looked at the frequency allocation rules and such. Quite often around certain frequencies you will see your not to cause interference with radar. However, a lot of radar in the S-Band pulse power tend be quite strong because of atmospheric attenuation, and also noise.

Additionally, lot these weather radars are not trying to achieve same level of accuracy as an altimeter. If the weather formations ones monitoring is off by a little bit, but overall the data is close it's fine. Similar thing with a lot maritime radar, ships are not moving that fast so you also have a lot more time to average out the data. If an altimeter when landing is off by too much can cause a lot problems, especially when you factor in the speeds of an airplane it's you have less time to average out noise or doing other things to filter out spurious noise. Edit: Also one other thing about maritime radar there nowhere as much interference once you get outside ports or areas near land.

Also it's not just Boeing here having issues, airbus also along with Boeing has brought this to the attention the FAA. The frequency bands in other countries for 5G tend to be farther away as well from the frequencies used by altimeters so it's not been issue in other countries. It only seems to be handful of air-frames that effected.

Secondly, NOAA have been concerned about 5G, particularly near 24Ghz, again for possibly interfering with radar.

All I was saying is radar is a lot more sensitive to the noise floor and if suddenly that noise floor is higher I am not surprised some equipment will have issues depending on it's use case. Especially, when things were designed long before these new spectrum allocations.

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Re:FAA says 5G could impact radio altimeters on most Boeing ... by hilbert42 on Thursday February 24, 2022 @08:45PM (#30462773)

"Especially, when things were designed long before these new spectrum allocations."

See my post about international radio regulations, the 5G service should not have been allocated if it was going to interfere with radar altimeters as that was (and still is) a 'going' service and it takes precedence under international radio treaties.

Thus, an aircraft from a country that's not under US jurisdiction expects to be able to land in the US without its radar altimeter being jammed by some unexpected local service. (It stands to reason that the safety of an aircraft that travels across international borders should not be endangered because of inference to its navigation equipment.)

This is the precise reason why international radio regulations exist! Under the treaty the 'interference' rules apply to ALL radiocommunication services.

If such regulations (standards) are deemed 'old' then they have to be changed at an ITU WRC meeting in Geneva and the item must appear on the meeting's agenda some years before said meeting takes place to give all countries adequate time to respond (as I mentioned elsewhere, I was once involved in that process).

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