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| 5G versus commercial aircraft Radio Altimeters in the US, wtf? |
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| Gyro:
--- Quote --- Rule #1. Follow the money. I wonder how much the US cell phone carriers expect to make from the 5G market? And what would it cost them out of pocket to replace it with something else if the 5G system was completely shutdown? --- End quote --- Well they (AT&T and Verizon) paid the FCC $69bn for the rights to the C band frequencies, so they obviously expect to make a fair bit. It does feel as if the FCC were squeezing the pips a bit... South Korea use 3.5GHz, Europe use 3.7GHz and the US, 3.98GHz. Edit: According to what I saw on the BBC News last night, AT&T and Verizon weren't warned about the 'strings attached to their use of the frequency. In Canada, apparently the carriers have been instructed to orient their antennas downward near airports (don't know how well that works in practice). |
| jonpaul:
Bonjour, Use of radio altimeter is less and less as airlines use GPS, ADS-B, etc which give more accurate alt info. The admins mandarins with sinecures, have a lot of profit in this false fight. FCC and FAA politicians installed by recent US administration have replaced competent technical and engineering staff. The guard bands are adequate as deemed by FAA and FCC before. Now at the last minute JoBi's idiots change the rules. Expect more gov meddling in technical affaires to the detriment of our aviation AND telecom industries. Just the rambling of an old retired EE Jon |
| ve7xen:
--- Quote from: jonpaul on January 19, 2022, 07:16:24 pm ---Bonjour, Use of radio altimeter is less and less as airlines use GPS, ADS-B, etc which give more accurate alt info. --- End quote --- What? No. GPS altitude is based on a geoid, not the terrain, so it doesn't replace the radar alimeter; it's not very accurate anyway, baro altitude is better. ADS-B altitude is transmitted by the aircraft so totally irrelevant here. The radio altimeter is really the only accurate source of distance-to-ground information available, which is used primarily for EGPWS and for callouts during landing, which are both pretty important and not practical without RA (though I think EGPWS might use its terrain database + ASL/calibrated altitude in addition to RA, the RA data is obviously much higher resolution). Ultimately the fight is about money. Of course they can make the altimeters work just fine in the presence of this interference, but the interference is new and the equipment was designed around the usage regulations when it was created. Updating that equipment (or at least testing and re-qualifying it under new standards) is not free, and the aviation industry is quite reasonably chafing at the idea that they should foot the bill for telecom expansion that doesn't benefit them one iota. |
| SiliconWizard:
--- Quote from: ve7xen on January 19, 2022, 09:34:20 pm ---Ultimately the fight is about money. Of course they can make the altimeters work just fine in the presence of this interference, but the interference is new and the equipment was designed around the usage regulations when it was created. Updating that equipment (or at least testing and re-qualifying it under new standards) is not free, and the aviation industry is quite reasonably chafing at the idea that they should foot the bill for telecom expansion that doesn't benefit them one iota. --- End quote --- Absolutely. And in cases like this, if the State should have a role, it should at least be arbiter. Not just getting money from whoever gives more, including bribes. =) |
| jpanhalt:
At first, I wondered why radio altimeters were such a big issue. You have both a barometric altimeter, which is usually set to the local pressure, and on approach you have at least glideslope. During the time I flew general aviation (US), two of my airplanes had radio altimeters, and I never used them except for amusement. ;) One problem is that when flying into airports in the SW and mountain states, the surrounding terrain can be well below the airport's elevation. That might be bad, if one descended to 200 feet AGL before reaching the threshold. Then I looked at the AD notices. Apparently, in modern airliners, the radio altimeter is linked to important landing functions, such as reverse thrust and automatic braking. The two "passengers" in the front seats cannot control those independently. Once obvious solution seems to be ignored. Why not have the pilots make those decisions? |
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