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If 5G was using spectrum way outside the band that these altimeters are supposed to be using... then we wouldn't have this issue. Those 737s aren't new, they ce

If 5G was using spectrum way outside the band that these altimeters are supposed to be using... then we wouldn't have this issue. Those 737s aren't new, they certainly had permission to use that spectrum for years and while they may have had years to fix their equipment, it's certainly not as trivial as "add a high pass filter". Now, I do agree that this should have been caught 5-10 years ago, when the standard was being developed. Boeing's incompetence wouldn't surprise me, which is probably why we see "FAA says problems for Boeing in 5G" as the headline, instead of "Aircraft companies warn of interference in safety, navigation equipment, ask FCC to reconsider" as the headline, 5 years ago. Although, as noted in the article, it seems that the FAA has been warning about the conflict - I'm just surprised that the FCC would go ahead with 5G if they had been flagged early enough. So here we are, the FCC, in its negligence, assigned conflicting portions of the spectrum, Boeing, in its incompetence, didn't catch it - and now it's a big mess.

maxsilver 5y ago
>they should have caught this 5-10 years ago They mostly did. They've been warning about this for 3+ years now (see this report from the FCC back in September and October 2019) https://ecfsapi.fcc.gov/file/102214765103/AVSI%20RA%20Interim%20OOB%20Interference%20Report.pdf https://ecfsapi.fcc.gov/file/102214765103/AVSI%20RA%20Interi... They couldn't have warned folks about more than a year or so sooner than that, because the spectrum bands for 5G hadn't even been fully decided prior to it. (The public notice of band reconfiguration only got announced back in May 2019)
- ummonk 5y ago
  Yup, they should suspend the rollout due to noncompliance by airplane manufacturers and fine said manufacturers for the delay.
  - p_l 5y ago
    The aviation hardware was compliant with the FCC rules (transmitting only within 4.2-4.4 GHz). FCC didn't specify anything about received interference, and didn't apply any of the methods used elsewhere in the world to limit leaking by 5G towers in 3.8-4.0GHz range.
peeters 5y ago
> Those 737s aren't new, they certainly had permission to use that spectrum for years This statement seems to be at odds with what many others in this thread are saying: that they were never approved to operate in this band. I don't know enough about this issue to know who is correct--do you happen to have a source for that since you are certain of it?
- jaywalk 5y ago
  They never had permission to use the 5G spectrum, and in fact never did. The issue is that the filtering is so shoddy that signals more than 200MHz away from the band they are using can cause issues. The fault for that lies squarely on Boeing.
  - Lascaille 5y ago
    >The fault for that lies squarely on Boeing. Why? They don't make the radar altimeters and multiple aircraft manufacturers are affected. Why is Boeing at fault for issues that (also) manifest themselves on Embraer and Airbus aircraft?
    - jaywalk 5y ago
      Boeing is ultimately responsible for every part that goes into their planes. They didn't manufacture the equipment, of course, but they signed off on it meeting their standards.
avianlyric 5y ago
> Those 737s aren't new, they certainly had permission to use that spectrum No they don’t, and never have. Hence the current shit show today. Boeing got away with it because old users of the 5G spectrum where lower power satellite comms. Hilariously the oldest 737 model is unaffected by this issue, probably because Boeing actually let their engineers do good work back then, rather than forcing them to produce the sloppy crap they build today in the name of profit.
initplus 5y ago
Well the whole point is they didn't have permission to use that spectrum. The interference the FAA is complaining about is explicitly outside of the radalt allocated spectrum. FCC has allocated radalt's 200Mhz, with another 200Mhz guard on either side. If these devices are not properly filtering out frequencies outside of this massive 600Mhz range, those devices are faulty and should never have been certified by the FAA in the first place. It's reasonable for the FCC to assume that spectrum users will not be affected by interference from so far outside their allocation.

maxsilver 5y ago

>they should have caught this 5-10 years ago They mostly did. They've been warning about this for 3+ years now (see this report from the FCC back in September and October 2019) https://ecfsapi.fcc.gov/file/102214765103/AVSI%20RA%20Interim%20OOB%20Interference%20Report.pdf https://ecfsapi.fcc.gov/file/102214765103/AVSI%20RA%20Interi... They couldn't have warned folks about more than a year or so sooner than that, because the spectrum bands for 5G hadn't even been fully decided prior to it. (The public notice of band reconfiguration only got announced back in May 2019)

ummonk 5y ago
Yup, they should suspend the rollout due to noncompliance by airplane manufacturers and fine said manufacturers for the delay.
- p_l 5y ago
  The aviation hardware was compliant with the FCC rules (transmitting only within 4.2-4.4 GHz). FCC didn't specify anything about received interference, and didn't apply any of the methods used elsewhere in the world to limit leaking by 5G towers in 3.8-4.0GHz range.

peeters 5y ago

> Those 737s aren't new, they certainly had permission to use that spectrum for years This statement seems to be at odds with what many others in this thread are saying: that they were never approved to operate in this band. I don't know enough about this issue to know who is correct--do you happen to have a source for that since you are certain of it?

jaywalk 5y ago
They never had permission to use the 5G spectrum, and in fact never did. The issue is that the filtering is so shoddy that signals more than 200MHz away from the band they are using can cause issues. The fault for that lies squarely on Boeing.
- Lascaille 5y ago
  >The fault for that lies squarely on Boeing. Why? They don't make the radar altimeters and multiple aircraft manufacturers are affected. Why is Boeing at fault for issues that (also) manifest themselves on Embraer and Airbus aircraft?
  - jaywalk 5y ago
    Boeing is ultimately responsible for every part that goes into their planes. They didn't manufacture the equipment, of course, but they signed off on it meeting their standards.

avianlyric 5y ago

> Those 737s aren't new, they certainly had permission to use that spectrum No they don’t, and never have. Hence the current shit show today. Boeing got away with it because old users of the 5G spectrum where lower power satellite comms. Hilariously the oldest 737 model is unaffected by this issue, probably because Boeing actually let their engineers do good work back then, rather than forcing them to produce the sloppy crap they build today in the name of profit.

initplus 5y ago

Well the whole point is they didn't have permission to use that spectrum. The interference the FAA is complaining about is explicitly outside of the radalt allocated spectrum. FCC has allocated radalt's 200Mhz, with another 200Mhz guard on either side. If these devices are not properly filtering out frequencies outside of this massive 600Mhz range, those devices are faulty and should never have been certified by the FAA in the first place. It's reasonable for the FCC to assume that spectrum users will not be affected by interference from so far outside their allocation.