[HN Gopher] FAA Shows 'Sample NOTAMs' for Possible 5G Restrictions
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FAA Shows 'Sample NOTAMs' for Possible 5G Restrictions
Author : Stevvo
Score : 42 points
Date : 2021-12-26 17:02 UTC (5 hours ago)
(HTM) web link (www.avweb.com)
(TXT) w3m dump (www.avweb.com)
| trebligdivad wrote:
| What's different in the US from the rest of the world that's been
| running 5G for a while?
| thetinguy wrote:
| 5g has been running for a couple of years in the US. The FAA's
| problem is new spectrum that carriers want to deploy.
| huslage wrote:
| They have deployed it, it's just not turned on yet.
| londons_explore wrote:
| Different countries use different frequency bands for both 5G
| and radar alitmeters.
|
| The FAA's concern here is that the bands will be neighbouring
| in the USA, which means if either the 5G equipment accidentally
| transmits a bit of signal outside its allocated band, or the
| altimeters accidentally interpret out-of-band signals they
| ought to ignore, then problems could happen.
|
| Since radar altimeters are pretty old tech, and very analogue,
| their concern isn't totally unwarranted.
| trebligdivad wrote:
| Thanks; so then the question is hth did the US manage to do
| this 5G allocation without thinking about the consequence?
| bdamm wrote:
| FAA is actually quite good at ignoring theoretical non-
| problems.
|
| This is a sample notam for what the anti-interference alert
| will look like.
| NavinF wrote:
| The bands seem to be 200mhz apart, which is a massive gap.
| If it was my decision, I wouldn't think of any
| consequences. I still think this will only affect the
| crappiest of hardware with the crappiest of filters.
| p_l wrote:
| a single radar altimeter's operating bandwidth can be as
| high as 200MHz, though (In fact, higher bandwidth
| increases resolution and quality of return)
| NavinF wrote:
| That has nothing to do with the frequency allocation. You
| can't just transmit outside your band hoping it will
| increase resolution. And receiving 200mhz outside your
| band is not a thing we do in <current century>. DSP
| exists.
| upofadown wrote:
| I am pretty sure that the concern is with the results of
| front end overload, which happens well before DSP can be
| applied.
| londons_explore wrote:
| To add detail... A major part of FCC testing of hardware
| is that it will work correctly _even when other people
| are transmitting stuff on other frequency bands_.
|
| So, provided all hardware out there went through the
| proper FCC tests, and nobody cheated, then it's
| guaranteed to work.
|
| The issue is that what the FCC rules say, and how devices
| in the field actually behave, can differ...
| VLM wrote:
| > The issue is that what the FCC rules say, and how
| devices in the field actually behave, can differ...
|
| That's the point of the situation. You replace the radar
| alt on aircraft #2153 and you do not trust it until its
| got a few hours and thats "ok". There are published
| minimums and a safe pilot will not push those with
| something that was just bolted together.
|
| The exciting part of 5G is its like every radar alt in
| every aircraft flying in the entire country just got
| replaced and can't be trusted until proven otherwise for
| a week or two. No biggie. I suspect some will indeed fail
| and be replaced and that'll be OK because nobody will be
| trusting their radar alt for the first week 5G is turned
| on. And after that it'll be "fine".
|
| Its kind of like the effect of EMP on cars. Disaster
| doomers like the mythical story of one "boom" and all
| cars stop, however comically unrealistic that is. Reality
| is you could still cause chaos logistically by hitting
| just 0.1% of all cars because our supply chain, even
| without covid, is absolute trash. And that's how this
| 5G/radar situation will turn out. Most likely the supply
| chain for avionics literally can't handle replacing, say,
| 0.1% of all radar alts currently installed in aircraft
| today. Can aircraft spruce and specialty literally ship
| 500 radar alts on monday if someone snapped their fingers
| and turned 5G on? Are there enough bored A+P mechanics to
| install all of them or will aircraft sit waiting for
| parts to arrive or get installed? Hilarious to consider a
| fixed base operator trying to order ten radar alts
| shipped by air priority and the air priority is down, so
| we're waiting on trucks. Then just like toilet paper or
| microcontrollers during covid, you'll have idiots panic
| buying two year supplies "because there's a shortage"
| resulting in plenty of people needing parts and having
| zero access. So if your average airline needs ten
| replacement radar alts per year and the supply chain
| might be F-d for two years they need to panic order
| twenty radar alts and stick them in closets (and order
| that RIGHT NOW like today...); they may only need three
| when 5G is turned up and then seventeen other aircraft
| will have to sit on the ground waiting for parts because
| "their" radar alt is sitting in someones hoard/warehouse.
| hokumguru wrote:
| Most people don't realize that the vast majority of GA
| aircraft are positively ancient though. When the average
| hardware among hobbyists is >30 years old the definition
| of "crappiest of hardware" takes on a different meaning.
| throwawayboise wrote:
| Many GA airframes are old, but have been refitted with
| "glass cockpits" from Garmin or other avionics companies.
| huslage wrote:
| There are no ancient GA aircraft with RADALTS or autoland
| systems.
| JCM9 wrote:
| Layman's explanation:
|
| When modern planes land in bad weather, especially fog, the
| height off the ground is determined by bouncing radio waves off
| the ground. Essentially radar pointing down off the bottom of the
| plane. This provides added safety over the normal altimeter
| measurement using air pressure. 5G frequencies are too close to
| the frequencies used for this radar and so the theory is that
| this will cause dangerous interference that could cause issues
| during a critical phase of landing. Without these systems
| aircraft would not be able to use certain instrument approaches
| and thus couldn't land during certain weather conditions when
| they can today. If the FAA pulls the plug on these it would cause
| big headaches during times when today planes can land without
| issue.
|
| tldr 5G might stop you from getting to your destination on time
| or at all on a future flight.
| sokoloff wrote:
| That explanation is correct but somewhat incomplete. Precision
| approaches with low minimums (the decision point where a missed
| approach must be initiated) also have an alternate source of
| vertical guidance (in the typical case of an ILS, it's a radio
| beam bounced off the ground and up along the approach path and
| the pilot has a very tight indication of whether they're below,
| on, or above that beam).
|
| The radio altimeter is a secondary or tertiary source of height
| above terrain information, not a primary.
|
| Without a functioning radio altimeter, some aircraft on
| approach to some runways would have to use higher minimums than
| would be available if they have a functioning unit. This will
| contribute to some missed approaches or diversions in low
| weather. (Where a missed approach almost never ends in a crash
| in airline operations but rather a second attempt or a
| diversion.)
| Rebelgecko wrote:
| Is this a legado (nee lightsquared) issue, or a whole nother
| problem?
| RF_Savage wrote:
| This is different from the Lightsquared L-band LTE proposal.
|
| This is about the C-band 3.5GHz 5G spectrum.
| upofadown wrote:
| It is similar in that both situations resulted from the
| reallocation of a satellite downlink band to terrestrial use.
| Suddenly the the band that only had transmitters in space
| barely detectable on the ground has actual transmitters on the
| ground. It's like having noisy people move in next door when
| the previous occupants were very quiet.
| gormandizer wrote:
| In my opinion this is required reading:
| https://wetmachine.com/tales-of-the-sausage-factory/what-the...
| varelse wrote:
| So 5G may end up protecting us from chemtrails? What's a
| conspiracy nut to do?
| akkawwakka wrote:
| I recommend checking out Juan Browne's video [1] that contrasts
| studies from the aviation world and one from the telecoms.
| Spoiler: the former brings more technical analysis than the
| latter.
|
| I'd love to know why the FAA is 'rolling over' to the telecoms /
| FCC on this matter. The spectrum was in use for RADALTs before 5G
| and safety systems like autoland, used when visibility starts
| coming down to minimums, rely on them.
|
| Seems to me that, like Canada, the US should just not allow 5G
| cell sites near critical areas around an airport.
|
| [1]: https://youtu.be/942KXXmMJdY
| tssva wrote:
| The spectrum in question was never allocated for use by
| RADALTs. Prior to being allocated for 5G use it was used for
| C-band satellite transmission. If there is an issue of
| interference with RADALTs the real question should be why did
| the FAA allow deployment of RADALTs in aircraft which could not
| operate in their allocated frequency band without risk of
| dangerous interference from already assigned frequencies. The
| second question should be what is the FAA, aircraft and airline
| industry going to do to quickly correct the issue they created.
| InTheArena wrote:
| Its also worth remembering that the FAA insisted for years and
| years and years that any sort of cell phone / iPad / laptop use
| in flight would cause a accident - with the same sort of scare
| tactics as used here. They eventually backed off of that and
| insisted it was only during takeoff and landing..
|
| This playbook has been run before.
| mdasen wrote:
| I think there's a lot of pressure to get the spectrum in the
| hands of wireless carriers. They spent nearly $100B on that
| spectrum and Verizon and AT&T are anxious to put it into play.
| T-Mobile already has mid-band spectrum for 5G at 2.5GHz and
| they're seeing customers on their mid-band spectrum get speeds
| of around 300Mbps. As their mid-band coverage expands, Verizon
| and AT&T won't want to be left behind. Likewise, the
| administration would like for the US to be seen as a 5G leader.
| We see articles with headlines like "US carriers advertise 5G,
| but their speeds lag other countries." A huge part of that is
| that Verizon and AT&T haven't been able to deploy new spectrum.
|
| I don't know enough about how far around airports they'd want
| to block C-Band from being used, but in a city like San Diego,
| it would probably block off a decent amount of the city given
| where its airport is. In a place like New York, how far would
| you want to block off? Clearly not all of bravo airspace, but
| how much is needed (maybe you know how much Canada had to block
| off)?
|
| I'm not sure that the FAA is rolling over. In some ways, saying
| "we're going to make air-travel suffer huge problems if they
| start activating C-Band spectrum" is saying "if you activate
| C-Band spectrum, Congress is going to start having hearings as
| to why the government is letting wireless carriers prevent
| people from traveling." I think the FAA is noting exactly how
| bad the situation might be if they go forward with C-Band
| plans.
|
| I think it's also a situation where people might be unsure who
| has authority. Can the FAA ban wireless signals that the FCC
| says are ok? Can one government agency take another to court
| despite being part of the same administration? At some point
| the administration controls both and might need to make a
| decision.
|
| But I think there's a lot of pressure to let C-Band go forward.
| Wireless carriers are looking to 10x their wireless networks
| and it seems likely that wireless home internet will become a
| big way that more rural areas get high-speed internet (even
| C-Band signals can get decent range with good antennas and
| using low-frequency spectrum for uploads).
| oliveshell wrote:
| I'll second that recommendation. For any who don't know him,
| Juan Browne's videos are the best resource I've found for
| sober, no-bullshit reporting and analysis on everything related
| to aviation.
|
| Juan (a.k.a. Blancolirio on YouTube) is an airline pilot and
| former military aviator who doesn't sensationalize and really
| knows his stuff.
| aDfbrtVt wrote:
| How could the 200MHz spacing between the frequency allocations be
| insufficient? I can't imagine the oscillators in either system
| are specified for deviations as high as +-100MHz over their
| lifetime.
| upofadown wrote:
| That's a 200MHz spacing at a 4400MHz working frequency. For
| some sort of physical filter this stuff tends to work in terms
| of percentages. That is only something like 5%. So pretty
| close.
|
| Normally you have lots of space to waste at higher frequencies
| for guard bands and you can allocate compatible uses for next
| door bands. Still, when you get a powerful transmitter right
| next door there are often problems. The previous tenants of
| that spectrum (C band satellite downlinks) used to have a
| problem with interference from radar altimeters. So I suppose
| there is some sort of karmic process here where the service
| that used to cause interference is now the service that is
| getting hit with interference.
| xxpor wrote:
| You're right: they're perfectly fine. This whole thing is FUD
| from someone... just not sure who yet. My understanding is this
| band has been used for Europe for a few years already.
| p_l wrote:
| With effectively 400 MHz guard band, though.
| onphonenow wrote:
| Yeah, and all this drama vs actually you know, testing things
| in the 10 years they've had is rediculous by the FAA.
|
| Seriously, just test it.
|
| You have thousands of flights a day. On a day with visual
| flight rules put a transmitter at 4.0ghz, max power, worst
| case radiation pattern and land a 737, 787, A320 and A321 etc
| as a test.
|
| There is something going on here that we don't know about.
| VLM wrote:
| Phase noise is obviously the problem. Plenty of microwave
| broadband gear isn't all that narrowband to begin with...
|
| Note there's a pretty big difference between "it should be good
| enough for 99.99% of planes" and "we can guarantee there won't
| be even one crash even under unlikely conditions".
|
| Aerospace is already VERY comfy doing ADS-B at 1090 and
| DME/TACAN from 960-1215 and the old GPS L1 allocation at
| 1575.42 and the military L2 allocation at 1227.60 (admittedly
| not many civies using that LOL) and someday probably L4 and
| remember ASR-11 airport radars blast at 25 KW power over
| 2700-2900 MHz. But, you know, the straw that broke the camels
| back and all that.
|
| Most things will be fine. A small amount of things will operate
| degraded, which is the point of the NOTAM. Some things (like
| very few) will all fail the same time 5G is deployed, which
| will be a headache. Going forward every installation of every
| device on the ground or in the plane will be tested against 5G
| and it'll be just fine. Most likely for a week or a month
| everyone will have to treat their radar altimeter as
| potentially broken until proven otherwise, then it'll be fine
| and they'll drop the notam. Some equipment will indeed fail and
| connectors will be tightened or even devices replaced, and
| it'll be fine.
| jdiez17 wrote:
| I was also curious about this, so I looked at the Airworthiness
| Directive[1] referenced in the example NOTAM. Basically, the
| argument is that the radio altimeter receivers "must detect
| faint signals reflected off the ground to measure altitude" and
| [C-band 5G signals] "could significantly degrade RA functions
| [...] if the altimeter is unable to sufficiently reject those
| signals".
|
| So it seems it is basically a question of how wide is the RF
| input filter bandwidth of RAs on commercial aircraft.
|
| [1]
| https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf...
| p_l wrote:
| I'm not good with analog circuits, but someone mentioned in
| previous thread that designing a 200 MHz wide filter that
| would have "brick wall" response to frequencies outside it is
| non-trivial, and technically the 200MHz is just the transmit
| range, not receive range...
| guerby wrote:
| This is all ridiculous, there's still a 200 MHz band guard
| between the FAA band and the 5G proposed band.
|
| Here is what a $1 ESP wifi dongle has to follow:
|
| https://en.wikipedia.org/wiki/IEEE_802.11
|
| "The mask requires the signal to be attenuated a minimum of
| 20 dB from its peak amplitude at +-11 MHz from the center
| frequency"
|
| So 2 dB/MHz filter.
|
| I let you do the math.
|
| FAA is just ridiculous here if they let old junk radio
| hardware handle safety landings for airplanes, but well
| after 737 max what do you expect...
| aDfbrtVt wrote:
| That's why virtually every RF frontend oversamples
| sufficiently to do the sharp filtering in DSP.
| pgorczak wrote:
| Although when receiving a weak signal with strong out of
| band interference, you may still need a lot of dynamic
| range to successfully filter it out digitally.
| VLM wrote:
| 3rd order IMD performance can become an issue.
|
| 3rd ord IMD for non-EE could be described as low power
| mixers like mixing low power signals and usually the low
| power signal comes from your intentionally designed radio
| oscillator, but, whack it with enough incoming RF power
| and it will go non-linear as its designed to do and start
| mixing with that incoming signal, mostly making massive
| levels of interference. You can always improve 3rd order
| IMD by simply running the oscillator and mixer at higher
| power levels (which all turns to heat), usually not the
| best strategy for battery powered gear.
| sandworm101 wrote:
| >> There are concerns that 5G signals, which use 3700-3998 MHz,
| can overpower radar altimeter signals, which operate in the
| 4200-4400 MHz band.
|
| RADALTs are tricky things. They are finicky. Sometimes they get
| good reflections and sometimes they are confused by irregular
| terrain, particularly over urban areas. Imho 5G would, at most,
| cause radalt blackout/failure (ie no displayed altitude) rather
| than the far more dangerous false readings. And any interference
| should be intermittent. Unless you are hovering over a cell tower
| the strength of the 5g signal should rise and fall pretty quickly
| as the aircraft moves between cells.
| p_l wrote:
| That's why the areas most considered problematic are use of
| radar altimeter in terminal approach stages and automatic
| landing combined with high C-band 5G transmitters close to
| airport.
| AnthonyMouse wrote:
| Can somebody explain what 5G is actually good for?
|
| With 4G you get fast enough coverage at long distances for
| basically everything. Maps for sure, but even streaming video as
| long as not everyone on the tower is trying to do it at once.
|
| With 5G you get more bandwidth, but you're not going to get it in
| the middle of the woods because it also requires more towers
| closer together. So it's for high population density areas. But
| those areas are the places where it's extremely cost effective to
| install fiber, and cellular will never ever be as fast as fiber,
| and installing a million towers everywhere is just about as
| expensive.
|
| If 4G is about all you're going to get in the middle of the woods
| and fiber (with the last hundred meters over Wi-Fi for mobiles)
| is the thing you actually want in the city, why is anybody even
| wasting money installing 5G towers anywhere?
| mhh__ wrote:
| 5G covers what 4G does as well IIRC. The really high frequency
| stuff is only what makes the news.
|
| Also the advantage of 5G as far as I'm concerned is being able
| to connect things (possibly in a mesh?) At very high throughput
| without cables. If you have an oscilloscope and a signal
| generator, you should be able to synthesize a (say) network
| analyzer out of the two of them by linking them via 5G.
| AnthonyMouse wrote:
| > 5G covers what 4G does as well IIRC. The really high
| frequency stuff is only what makes the news.
|
| Right, right, the really high frequency stuff is what we're
| talking about. It's confusing that they stick so many things
| under the same label. The parts of "5G" that are just 4G with
| better radios and algorithms are useful but also not so
| contentious. But for that you wouldn't need more towers at
| closer intervals.
|
| > Also the advantage of 5G as far as I'm concerned is being
| able to connect things (possibly in a mesh?)
|
| And now we're talking about a third thing.
|
| It could actually be quite useful to open up more unlicensed
| spectrum for things like this -- if nothing else so we could
| get better Wi-Fi to hook up to the fiber.
|
| But that's a different thing than having Verizon install a
| cellular tower on the end of every street corner for high
| frequency cellular 5G and then _not_ having them come the
| rest of the way with the fiber into your house, which still
| seems like some kind of a bad joke.
| lettergram wrote:
| I think they aren't wasting money installing towers. You'll pay
| for those increased speeds as they build many towers.
|
| Although I agree, what we will end up with is going to be broad
| area WiFi effectively. Seems like the goal is to replace fiber
| and then you can move around the city always connected at high
| speeds.
|
| Comcast is already doing this, their routers will let other
| Comcast users connect over WiFi.
|
| Personally, I believe that is the end objective. I personally
| am just getting satellite via starlink and probably will get
| fiber if it's available.
| sandoze wrote:
| Lots of stuff covered. Here's a few more.
|
| In theory you should be able to take your private network
| anywhere there's 5G.
|
| Industrial Ethernet. Latency, jitter, and guaranteed delivery
| are required in many factories. Meaning they're still relying
| on cable, wiring, and proprietary PLC hardware close to the
| sensors.
|
| Private network slices.
| mycall wrote:
| 5G is under 3GPP release 17 now [1] which includes many new
| features than 4G as release 8 [2]. 5G is much more than just
| changes in speed.
|
| [1] https://www.3gpp.org/release-17
|
| [2] https://www.3gpp.org/technologies/keywords-acronyms/98-lte
| madspindel wrote:
| > but even streaming video as long as not everyone on the tower
| is trying to do it at once
|
| 5G Broadcast solves that. Radio, live TV, popular Netflix TV
| shows etc. could be broadcast and save a lot of bandwidth.
| llimos wrote:
| Not to mention vastly higher power consumption.
|
| In an age of increased awareness around climate change, it's
| fairly mind-boggling that 5G is being pushed so hard, given the
| questionable value of the benefits it brings.
| pas wrote:
| How does it increase power consumption?
| llimos wrote:
| Source: https://www.ericsson.com/495d5c/assets/local/about-
| ericsson/...
|
| This is a brochure for Ericsson's lower power innovations,
| but look at the baseline without their system. Graph on
| page 2.
| toast0 wrote:
| 5G is kind of three things.
|
| 5G on existing frequencies can do more data with the same
| spectrum. Something something MIMO. This is broadly useful, if
| you have an 5G capable device and your network updated their
| base station equipment. 5G and 4G are supposed to be better at
| sharing spectrum on demand vs 4G and 2/3G.
|
| 5G on new, nearby frequency, in the US, there was a second
| round of taking historically TV spectrum and reallocating it
| for communications. These bands will most likely need new
| antennas on towers as well as on handsets. These tend to be
| lower frequencies, which could be useful for distance and
| structure penetration, but may not always be built out.
|
| Then there's the millimeter wave stuff. Very high frequency,
| very fast, great for density, like maybe transit stations and
| arenas. This is the stuff that needs a tower on every light
| pole or whatever. I don't think this is going to get a lot of
| deployment, but it gets a lot of press. I think this is the
| part the FAA is objecting to for now.
| [deleted]
| RF_Savage wrote:
| The FAA is objecting to the use of the 3.5GHz band, as it's
| supposedly too close to the 4400-4700MHz radar altimeter
| band. This band is the primary one for 5G deployment world
| wide and interestingly no planes have been dropping or
| crashing due to it's use. Strange how the same planes landing
| in European capitals with widespread 3.5GHz 5G deployments
| seem to do fine there, but will experience dangerous problems
| on USA soil.
|
| 3.5GHz is also exlusively 5G and not used for anything
| cellular before. Outside of some old wimax deployments here
| and there, but those ware usually for fixed users not
| mobiles.
|
| 3.5GHz is also firmly in the centimeter bands. :)
| gdavisson wrote:
| AIUI the European usage of this band only goes up to 3.8GHz
| (see https://www.everythingrf.com/community/5g-frequency-
| bands-in... for example), but the FCC auctioned off band
| space up to 3.98GHz. Aircraft altimeters use the 4.2-4.4GHz
| band, so the new US allocation nearly halves the band gap.
| _That_ is what the FAA is worried about.
| tzs wrote:
| Europe is only using 3.4-3.8 GHz. The US is going up to 4.2
| GHz.
| RF_Savage wrote:
| Ah! That certainly explains some of it. I even checked
| and sure enough, the highest allocated block here is 3670
| - 3800 MHz.
| deelowe wrote:
| It'll be a boon for fixed wireless where last mile issues
| prevent running cable
| jdiez17 wrote:
| > Then there's the millimeter wave stuff. [...] I think this
| is the part the FAA is objecting to for now.
|
| mmWave 5G signals are in the 24-54 GHz range (f = c / 0.001 m
| [?] 30 GHz)
| therein wrote:
| This makes me nervous. The O2 peak at 60GHz. What are your
| opinions on it? If we get that peak of attenuation at
| 60GHz, what's happening to that energy?
|
| The common wisdom would say it heats up but that's not
| guaranteed.
|
| https://i.imgur.com/KUR4XmX.png
|
| https://i.imgur.com/iUD2v4D.png
|
| https://www.5gamericas.org/wp-
| content/uploads/2020/12/InDesi...
| lumost wrote:
| What else would happen to the energy? It'll turn into
| heat + some re-emissions.
| jcims wrote:
| Not to feed the trolls but here is one example:
|
| Tumor Treating Fields are an FDA-approved mechanism for
| treating certain cancers (mostly gliomas). The exact
| mechanism isn't understood, but it seems that prolonged
| exposure to low power alternating electrical fields in
| the 100-500kHz region interferes with cell mitosis [1]. I
| haven't read about it recently but at the time the
| speculation was that it was basically disrupting
| microtubule formation by physically agitating polar
| molecules involved with the process.
|
| The application from Optune and others uses contact
| electrodes to drive a small potential gradient though the
| skull and into the brain.
|
| We know radio frequency also affects polar molecules,
| mostly to heat up meals. Obviously at multi-GHz carrier
| frequencies we wouldn't expect to see this behaivor
| emerge. However, most digital protocols don't operate
| with continuous carriers..the break comms into frames and
| do things like frequency hopping at much lower
| periodicity than the carrier. If there was something
| dumping energy into the cytoplasm on a 2-10 microsecond
| interval, it could have similar effects.
|
| Do i think 5g is going to cure brain cancer? Probably
| not, but the body is ridiculously complex and can be
| surprising. I think we just have to find a way to be able
| to talk about these concerns fruitfully rather than just
| try to squash them, because that's generally where the
| trouble seems to start.
|
| 1 - https://pubmed.ncbi.nlm.nih.gov/33080774/
| jdiez17 wrote:
| Keep in mind that the EM field described in that study is
| quite strong and the transmitter is very close (actually
| in contact with the patient's skin). They talk about
| field intensities of 0.6V/cm. That means that if you put
| the two probes of a multimeter in the air separated by
| 1cm, it would read 0.6V. That's quite a lot. I'm not sure
| how to translate that to RF power, but it is many orders
| of magnitude more intense than what you could ever expect
| to receive from a mobile phone tower. Radio receivers are
| basically very fast and very sensitive voltmeters that
| work with field strengths on the order of microvolts per
| meter.
| therein wrote:
| Thank you. Pretty much the answer I wanted to give, but
| much better than I could.
|
| And I am not just trying to latch onto the first unknown
| that's brought up under my comment, these are very
| similar to the concerns that I had in mind and wanted to
| bring up.
|
| At the wavelengths we would now be dealing with and
| exposing ourselves to, there may be - and with some
| evidence already pointing there probably being surprising
| and not immediately intuitive (mostly) biological
| interactions or disruptions to interactions our biology
| relies on that we are yet unaware or haven't understood
| leading to phenomenons we haven't considered such as the
| example you've given.
| JaimeThompson wrote:
| "The common wisdom would say it heats up but that's not
| guaranteed."
|
| If it does something other than turn into heat the laws
| of thermodynamics are wrong which is somewhat unlikely.
| jdiez17 wrote:
| Sure, 60 GHz may be a resonant frequency of O2 molecules
| and signals at that frequency may transfer energy to them
| and thus heat them up.
|
| However, remember that radio signals lose energy to free
| space proportional to the (distance and frequency)
| _squared_ [1]. A 60GHz signal is attenuated by 88dB at 10
| meters. That means that if it is transmitted with 100 W
| (20dBW), the RF power that arrives at your position is
| -68dBW, or 0.000158 milliwatts. That isn't going to heat
| up much.
|
| [1] https://en.wikipedia.org/wiki/Free-space_path_loss
| mlyle wrote:
| Note that this math is misleading for calculating how
| much things will heat up, because effective antenna
| aperture of the thing that you'd heat up increases with
| the square of frequency. So the square terms of frequency
| cancel each other out.
|
| It's still small, but the best simple approximation is
| just to take the 100W and divide by the proportion of the
| antenna pattern your target occupies.
|
| A 100W source on 2GHz or 60GHz at 10 meters distance is
| going to dump about the same amount of energy into you.
| If the transmit antenna has 3dB of gain, that's going to
| be about 50mW.
| jdiez17 wrote:
| That's interesting. I'm not quite sure how that works but
| I'll look into it. If you have some resources, I'd
| appreciate it!
| mlyle wrote:
| See the derivation section in your link. It's assuming an
| isotropic antenna at the receiver, whose effective area
| gets smaller as the frequency increases.
|
| But people do not get smaller as the frequency increases:
| they occupy the same fraction of the 10m radius sphere
| around the antenna.
| RF_Savage wrote:
| The power levels are low to begin with, so heating up the
| air is hard to even measure, let alone notice.
|
| It's why 60GHz is license free and used for WiGig,
| wireless HDMI and short haul microwave links like the
| ones from Mikrotik.
|
| The heavy oxygen attenuation makes it commercially
| worthless.
|
| Same reason why there's a license free band on 24GHz too.
| 24GHz suffers from water vapor absorption and has heavier
| attenuation than adjecent bands thanks to that. For
| example Ubiquiti AirFiber uses license free 24GHz.
| desine wrote:
| There's also the issue that with 5G phased array
| antennae, tx power limits are not restricted as tightly.
| With a standard single tx antenna, it's easy to calculate
| the amount of EM energy it can create in the 3D space
| around the antenna. With phased array beamforming, you're
| using using multiple small antennae and amplifying the
| signal beyond the sum of the individual outputs. The
| safety ratings for EM radiation around phased arrays tend
| not to be calculated on the theoretical maximum TX power,
| but on the typical usage. The result is that with low
| enough level access to the firmware, someone could
| theoretically weaponize a 5G antenna to produce unsafe
| levels of RF energy, as well as aim the antenna without
| physically moving the hardware.
|
| This sounds far-fetched, and it is, but I wouldn't be
| surprised if we see it done in a lab, like some of the
| other practically infeasible but bleeding edge cool
| hacks.
| jdiez17 wrote:
| > With phased array beamforming, you're using using
| multiple small antennae and amplifying the signal beyond
| the sum of the individual outputs.
|
| No, that's impossible. The RF power imparted onto the EM
| field by any antenna array is equal to or less than the
| sum of the output power of each antennae.
| MereInterest wrote:
| I think the argument is that while the total power over
| the full 4p is equal to the sum of the input power, the
| constructive/destructive interference cause there to be
| higher power output within some solid angle. But my
| understanding is that the limit are for avoiding
| interference from other devices, not for human safety,
| and that any reasonable amount of non-ionizing radiation
| is incredibly safe for humans. Congestion wouldn't be
| impacted by the beamforming, because on average any
| increase in intensity at one angle would be countered by
| a decrease at some other angle.
| NavinF wrote:
| Stop spreading FUD. ~60ghz radar has been used by cars
| for for cruise control and parking for many years now at
| much higher power levels than what phones can transmit.
| Some phones have mmWave radar for gestures too. We'd use
| even higher frequencies if it wasn't for the terahertz
| gap.
| therein wrote:
| Spreading FUD isn't my intention. If anything I am hoping
| to alleviate the FUD that open-mindedly reading these
| documents and plans induce in my mind.
|
| I appreciate and read the honest and detailed technical
| takes on the topic here.
|
| Especially acknowledging uncertainty and a healthy amount
| of doubt are pretty essential to the epistemological
| pursuit. And fear may arise when the uncertainty and
| doubt are not dispelled with reason.
| speed_spread wrote:
| Semi conspiracy alert: 5G is mainly motivated by surveillance
| through IoT. 4G is still mostly ok as a regular "cellphone"
| network but isn't cheap enough to be embedded in every device.
| Many consumer goods now have a wifi option (like my new
| dishwasher) but it still need to be configured after
| installation, which many people won't care to do. 5G will make
| it cheap enough for manufacturers to bundle always-on cellular
| modems in every device. The cost of networking plan will be
| assumed by the manufacturer and be offset by the value of
| telemetry data collected and subscription services made
| possible by the always-on network. Special dishwasher cycles
| for an extra 3$ and other shenanigans. Obsolence no longer has
| to be preprogrammed but can be declared unilaterally at the
| time most convenient by and for marketing departments.
| AnthonyMouse wrote:
| I'm not seeing it.
|
| I mean yes, corporations are definitely going to attempt that
| and they can all die in a fire, but telemetry like that
| requires minimal bandwidth. It doesn't need "5G" for
| anything.
| therein wrote:
| And beamforming is going to be useful for having precise
| location as a part of the protocol itself.
| alphabettsy wrote:
| Doesn't the number of antennas make location more precise
| without beamforming? Doesn't seem like it has anything to
| do with location precision.
| IAmGraydon wrote:
| Why would 5G be cheaper to implement in IoT devices vs 4G?
| drevil-v2 wrote:
| > 5G will make it cheap enough for manufacturers to bundle
| always-on cellular modems in every device
|
| How do you figure that? Is there something special about the
| 5G electronics and chipset manufacturing that make would make
| it much cheaper than 4G electronics? I don't think this is
| true.
| teruakohatu wrote:
| Maybe scale? Not that long ago shields for Arduino with
| WiFi were crazy expensive, now esp8622 devices cost so
| little I don't know how many I have lying around.
| kjellsbells wrote:
| 5G means so many things to people it gets muddy.
|
| If you are Verizon or ATT, you have lots of mmwave spectrum, so
| your interest is in dense urban environments and multi-dwelling
| units where your speed let's you compete against wifi and cable
| providers. You spent a bazillion on spectrum and you need to
| give your customers reasons to pay extra for their service.
|
| If you are t-mobile, you have a ton of mid range spectrum.
| After all, that was the only reason you bought sprint. You will
| want to go after consumers with a coverage play, since that is
| better than mmwave from T and VZ. You might also dip your toe
| in business services like IoT for farmers and factories.
|
| If you are a hyperscaler, you need CBRS (3.5GHz) to take off.
| You'll be pitching IoT and edge compute like crazy because the
| radio coverage is better than wifi, the speeds are good and
| best of all the spectrum is available at essentially nominal
| cost.
|
| What you won't get just yet, but will hear about a lot, are the
| toys like vr robots. The ugly truth is that no one really knows
| what the killer app for 5g is yet, but every operator is
| terrified that just like 4G theyll miss the value chain and
| leave apple or whoever to ride their network and slurp up the
| profit.
| ec109685 wrote:
| Yet, those legacy operators haven't invested a bit in an
| engineering and software organization capable of competing
| with the apple's that ride their network.
| kjellsbells wrote:
| Id argue that the telco industry tried, and failed, as
| opposed to not trying at all. ATT for example sent a
| boatload of people on training from Georgia tech, invested
| massively in automation... and couldn't pull it off.
|
| I also blame the industry for missing the point on the
| whole pivot to virtualization. For those of you not in
| telco, telcos got together in 2012 and said, "how can we be
| more nimble like the cool kids?" and concluded that
| virtualizing everything, was the way to go, as if all it
| took was a vm and a k8s pod. Really it was about culture
| and supply chain, but that's a whole other story.
| tyingq wrote:
| A document from pilot unions that expands a bit on the issue:
| https://www.icao.int/safety/FSMP/MeetingDocs/FSMP%20WG11/IP/...
| NelsonMinar wrote:
| That has helpful technical info on the technical problem. Radar
| altimeters work in 4.2-4.4GHz. Some 5G systems use 3.7-3.98GHz.
| The document describes mostly theoretical problems; the only
| actual example they site was part of a deliberate radar jamming
| military test.
| RF_Savage wrote:
| Yep. There has been a lot of talk about intererence. But no
| measurements or proof of any real world harm has not been
| presented. It has been going for years.
| yellow_postit wrote:
| Is there a path to disprove the potential for interference here?
| This seems like an nearly impossible "prove a negative" task that
| likely becomes so common people ignore it as noise which seems
| counterproductive.
|
| Side note: NOTAM is a notice to pilots [1] the article doesn't
| expand on.
|
| [1]: https://en.m.wikipedia.org/wiki/NOTAM
| bdonlan wrote:
| Presumably once this is broadly deployed, flight checks can be
| performed to check for interference.
| kylehotchkiss wrote:
| Will 5g also affect radar-based cruise control in cars?
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