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Their views aren't even that logical. You already need multiple radar altimeters on ONE plane much closer physically and spectrum wise than 5G. In busy airport

Their views aren't even that logical. You already need multiple radar altimeters on ONE plane much closer physically and spectrum wise than 5G. In busy airports you already have multiple altimeters operating again closely physically. Anyways, even if there is interference, it's actually boeing that should fix their systems to operate within their assigned band (ie, operate in the middle of the band, and reject signals outside of band). This is radio 101 stuff.

p_l 5y ago
Only one radar altimeter is generally operational at a time (transmitting), due to high bandwidth involved, and latest ICAO working group reports are "we don't know yet if it's safe with current equipment, retrofitting will take years as they can't even start designing new models till interference data is available, and that countries are implementing temporary mitigations in 5G base stations"
- onphonenow 5y ago
  That's where we find how technically incompetent ICAO is I suppose? Something that has been a decade in the making, they haven't been able to conduct basic tests on. I'm a lay person, but can easily think of basic tests that would help resolve this question. "On a large aircraft two or three altimeter systems are employed and these systems could utilize a frequency offset of 5 MHz to 10 MHz." Something is rotten with the regulators.
  - p_l 5y ago
    Radio altimeters have bandwidth as high as 170MHz, and a lot of work goes into ensuring other devices in 4.2-4.4 band do not interfere with them. The fact that certain radio systems can utilize low bandwidth does not mean every system is like them.
    - onphonenow 5y ago
      Are you sure? That's an almost impossibly high receive bandwidth for an older type of equipment I would think. I've seen bandwidth ranges of 50Hz to 300Hz (that's Hz not KHz or MHz). This is swept or chirped over a frequency (bigger is better for that - so 200Mhz good and they'd probably want more). But in terms of a guard, you should be able to guard much tighter than 200Mhz - that's what I'm not understanding - but haven't looked at it closely.
      - p_l 5y ago
        Frequency Modulated Continuous Wave radars used for most civilian radar altimeters sweep most of 200 MHz bandwidth, largest known case is 196 MHz. Transmit power ranges between 0.1 to 100W.[1] As another commenter mentioned, making a broadband filter for such wide bandwidth is... problematic, and it's one of those devices where you might want to use fixed function rather than SDR. [1] https://www.icao.int/NACC/Documents/Meetings/2018/RPG/RPGITUWRC2019-P08.pdf https://www.icao.int/NACC/Documents/Meetings/2018/RPG/RPGITU...

p_l 5y ago

Only one radar altimeter is generally operational at a time (transmitting), due to high bandwidth involved, and latest ICAO working group reports are "we don't know yet if it's safe with current equipment, retrofitting will take years as they can't even start designing new models till interference data is available, and that countries are implementing temporary mitigations in 5G base stations"

onphonenow 5y ago
That's where we find how technically incompetent ICAO is I suppose? Something that has been a decade in the making, they haven't been able to conduct basic tests on. I'm a lay person, but can easily think of basic tests that would help resolve this question. "On a large aircraft two or three altimeter systems are employed and these systems could utilize a frequency offset of 5 MHz to 10 MHz." Something is rotten with the regulators.
- p_l 5y ago
  Radio altimeters have bandwidth as high as 170MHz, and a lot of work goes into ensuring other devices in 4.2-4.4 band do not interfere with them. The fact that certain radio systems can utilize low bandwidth does not mean every system is like them.
  - onphonenow 5y ago
    Are you sure? That's an almost impossibly high receive bandwidth for an older type of equipment I would think. I've seen bandwidth ranges of 50Hz to 300Hz (that's Hz not KHz or MHz). This is swept or chirped over a frequency (bigger is better for that - so 200Mhz good and they'd probably want more). But in terms of a guard, you should be able to guard much tighter than 200Mhz - that's what I'm not understanding - but haven't looked at it closely.
    - p_l 5y ago
      Frequency Modulated Continuous Wave radars used for most civilian radar altimeters sweep most of 200 MHz bandwidth, largest known case is 196 MHz. Transmit power ranges between 0.1 to 100W.[1] As another commenter mentioned, making a broadband filter for such wide bandwidth is... problematic, and it's one of those devices where you might want to use fixed function rather than SDR. [1] https://www.icao.int/NACC/Documents/Meetings/2018/RPG/RPGITUWRC2019-P08.pdf https://www.icao.int/NACC/Documents/Meetings/2018/RPG/RPGITU...