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FAA reveals 50 airports that will have C-band 5G buffer zones
When AT&T's and Verizon's C-band 5G services go live on January 19th, they'll be implementing buffer zones around 50 airports in the US to reduce to risk of flight disruption. The Federal Aviation Administration has released a list (PDF) of the 50 airports it chose, which include major passenger hubs such as Chicago O'Hare International, Dallas-Fort Worth and Los Angeles Int'l. As The Wall Street Journal notes, it also includes airports in foggy and cloudy locations… (www.engadget.com) Más...
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Yes, radio frequency devices must not cause harmful interference AND must accept interference from other legally operated radio frequency devices. So if there are radio altimeters that don't meet these requirements, they are not legal and should be removed from operation.
Having said that, the buffer zones being implemented in the interest of safety are a reasonable short-term compromise until any non-compliant radio altimeters can be identified and replaced.
Having said that, the buffer zones being implemented in the interest of safety are a reasonable short-term compromise until any non-compliant radio altimeters can be identified and replaced.
Those devices met the current certication requirements of the day! Time and the money marches on.
Maybe the FAA requirements, but not the FCC requirements.
I dare say that the FCC requirements were probably less stringent when radar altimeters were actually TSO'd and bandwidth was almost completely unfettered by the modern proliferation of everything wireless.
You'd think C-Band buffer zones would be severely needed at smaller airports that have circle-to-land approaches where terrain awareness would be even more critical.
The problem is the Aviation altimeters and other items on the assigned aviation frequencies were designed poorly. The aviation receivers do not correctly filter for their assigned frequency and allow signals from near by frequencies to be received. In the 1980 the technology changed and newer receivers filter frequencies with precision. Before this time it was difficult and a wide area of spectrum was used. The aviation voice radios were updated to use the new tight frequency technology, not the addition of .25 radio assignments to provide many more voice channels and even data channels to send messages to aircraft. All inside the original frequency spectrum. The radio altimeters and some other equipment have never been built to modernized standards because the FAA kept the wide frequency assignment. The FAA has allowed, for years, Radio Altimeters to accept signals outside the aviation assigned frequency range. Now it is biting them. The manufactures should use the frequency spectrum tightly just like they do on other aviation and weather radar functions. They are also at fault for being lazy when designing new radar altimeter receivers for the last 30 years. No reason to spend the money on a better design when the FAA allowed it, as in allowed these receivers to be influenced by frequencies outside the defined range, just because the FCC did not have any allowed services in the adjacent frequency range.
Engineers at the FCC have been warning the FAA that this frequency use was approaching for over 10 years. And the FAA did nothing about it. As well as equipment manufactures took the cheap way out and followed the FAA's lead, knowing full well that the FCC was opening the adjacent frequency ranges.
Think of the root issue as being like old analog TV stations. They went digital and now assign sub frequency assignments inside the analog (old school) channels frequency spread to transmit 8 or more high-resolution signals. You new TVs easily filter out the adjacent frequencies to display a single channel. The FAA allowed these radar altimeters to be built with very old poor designs knowing what was approaching in the future. Someone at the FAA should be fired for not addressing this in the last 15 years, that is how long the FCC has been researching and planning this move.
This is not a 5G problem. As you little cell phones very easily filter to very tightly assigned frequency use. The radar altimeters can do the same thing if correctly designed. Cell phone use hundreds of assigned frequencies to have many phone calls all at the same time in one frequency space that a single radar altimeter uses. Also look at GPS, it has even tighter frequency bands.