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| Bluetooth Low Energy is unsuitable for COVID-19 contact tracing, say inventors |
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| vk6zgo:
My first thought when this App was mooted was that very low transmitted power levels can result in high received signal levels in a "direct line of sight" situation, so if the detection relied upon signal strength, there would be a lot of false positives. I then rejected that, saying to myself that I don't know enough about Blue tooth, & on second thoughts, maybe the two devices exchanged "handshakes", measured the time this took, & knowing the speed of light, calculated the distance between them. The problem with that is possibly latency in both devices is different, so adding another layer of possible error. But as I said, I know damn all about Bluetooth. I don't have a smartphone, just a dumb one, as I have a desktop PC & an IPad, & didn't see any sense in adding a "pretend computer" to that lot! |
| julianhigginson:
--- Quote from: cdev on May 14, 2020, 04:03:06 pm ---You have to understand, once somebody drops off the GPS and goes underground they could literally be anywhere. If they fill the metro stations etc. with BT beacons, thats still not going to get it to the level of accuracy it needs to be. --- End quote --- I understand a fair bit... I worked for a nursecall manufacturer for a couple of years, a few years ago now... we spent a *lot* of time trying to work out how to add location to alarm events while keeping the users' pendants low power, in ways that didn't also leave room for massive invasions of privacy or allow for incorrect locations to be sent. That was a very hard problem, and AFAIK the work on that project is still ongoing (as a background kind of thing) years after I left. The thing is, you've stated the problem with infection risk yourself... looking at the infection cluster data we have so far, a person's infection risk is about a person's proximity to an infected person indoors for an extended time.... it's not actually about *where* you are, but *who* you are near for long periods of time. BLE beacon tech on a smartphone can give us that. To some degree. now hear me out.. Yes it's obvious and I understand that the beacon app going off RSSI can't tell if you're 1m away from someone with a stud wall between you, or 5m away in the same room... that's definitely a shortfall in what the technology offers... BUT you can still identify long term proximity events... what you do with that data - refining it into usable information - becomes a problem for the people doing the actual contact tracing.. In other words the dumb open source BLE app isn't "the contact tracing", it's an important tool in a sustained and serious contact tracing effort. scenario one: 1) I, an un-diagnosed plague bearing wretch, go to a restaurant. 2) you go to the restaurant next door and get seated at a table right next to me, but on the other side of the wall 3) our phones make beacon friends as we sit down for an hour and eat our respective meals. 4) the next day I feel bad. 5) the day after i feel worse, and get tested 6) test comes back positive. 7) I give my app's recorded beacon buddies to the contact tracer people, and give them a list as best as possible of everywhere I spend extended periods of time over the last few days before I got sick (thanks, google location history!) 8) they find you in my list and contact you. 9) they confirm where you were on the day our beacon friendship blossomed. 10) they discover you weren't in the same space as me, and realise that you're probably not at risk. Scenario 2 - the diff edition: 2) on this day cruel fate made you pick the same restaurant as me (I mean we're beacon buddies right, it's natural we would have the same tastes in pizza) and sit across the room, all socially distanced like we're not really beacon buddies. but we know different. 10) they discover we were in the same room for an hour. so you get tested. AT the point where it's highly unlikely you would be contagious or sick. so you need a test too. 11) you come back positive (I'm really sorry, buddy.... I.... I didn't know... I had no idea....) 12) you've just been given the chance to save everyone you spend time with from a big chance of being infected. Also you've got the chance of commencing any available treatment right at the onset of infection rather than once you're very sick. TL;DR is: beacon app bad people using beacon app intelligently good. |
| SparkyFX:
--- Quote from: Someone on May 15, 2020, 01:10:44 am ---the rest of the system can be full of holes. So the government stands up and makes lots of noise about how secure and private the user app is, entirely honestly, distracting people from how the system actually works and the privacy issues it has. --- End quote --- It is the same (type of) government that funds Solar Roadways-like applications... okay? Coming of age usually includes to find out how clueless many many people are (inside or especially outside their field of expertise), and that is the step conspiracy theorists never got over. |
| tszaboo:
--- Quote from: julianhigginson on May 14, 2020, 12:28:47 pm ---I think that going on and on about the RSSI strength detection thing and thinking it has to be perfect or it's useless is missing the point. --- End quote --- Yeah, but this is a virus. It doesnt work like radioactivity or as a aura around people. That 1.5m rule they say everywhere is better than nothing but it is not even close to modeling all the transmission methods. You can spend probably hours within 1.5m from someone, and turn up fine, if you are facing the opposite way. On the other hand if someone sneezes at you from 10m, you might get what they have. Or you touch a door knob, that someone infected touched a day ago. Or they grab a bottle of milk, that you buy, put in the fridge, the virus goes to sleep mode, and reactivate itself two weeks later. So I guess bluetooth should track these as well. There is a way for mobile phones to help in this situation. Build in an infrared temperature meter, to quickly measure forehead temperature. |
| cdev:
I am going to go out on a limb here and say that the worst, by far situation for a city dweller is public transportation. Everywhere else I am in the city, I have some modicum of controi, I can choose to walk way on the dege of the sidewalk or even step off the curve and walk in the street (against the traffic so I can see it coming) But the one place where people cant prevent being right next to people is in the subway or to a lesser extent on busses. The only technology that works for telling where people actually are in that setting is high resolution CCTV. I think this Bluetooth effort is destined to be unsuccessful for the reasons they said. By the way, people should be aware how often various surveillance devices are being used now in public places. If you are wondering, its easy to show how often transponder type devices like "EZ-Pass" are queried. These devices arent just where tolls are collected, they are everywhere. License plate readers and most likely devices that log Bluetooth Mac addresses too. |
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