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Bluetooth Low Energy is unsuitable for COVID-19 contact tracing, say inventors
cdev:
--- Quote from: Syntax Error on May 13, 2020, 04:42:45 pm ---How about good old fashioned 1990's style IRD? We wear an IR transceiver on our facemasks.
Seriously though, BLE contact tracing apps are reliant on data exchange after a BLE connection has been made between two devices. In practical terms, kein problem in a low density environment with few people, but what about walking through a high density (high risk) place like a crowded metro station? Is there enough time for devices to advertise, connect, exchange, hang up and repeat, when you're walking as quick as you can through the 'danger zone'? How many devices get missed?
btw I came across this informative primer on BLE Advertising, which is the core technology for most contact tracing apps. https://www.argenox.com/library/bluetooth-low-energy/ble-advertising-primer/
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It looks like battery life may become an issue. How much, its hard to say.
SiliconWizard:
--- Quote from: SparkyFX on May 13, 2020, 07:21:45 pm ---(Near) Ultrasound/Sonar would circumvent the problems with EM-reception field strength indication vs. physical contact, but most people carry their phone in pockets, introducing lots of noise and dampening, making a distance measurement hard
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I would personally not expect it to really be of any use outside of ideal conditions indeed.
Syntax Error:
--- Quote from: cdev on May 13, 2020, 08:29:30 pm ---It looks like battery life may become an issue. How much, its hard to say.
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Maybe a moot point for many Android smart phone owners as the Covid tracking apps only run on the latest edition of the operating system. Globally ~60% of Android phones are not up to version 6.0, me included. 6.0 is baseline for the Australian and the UK Beta apps. On the other hand, Apple iOS offerings at 10.0 would only exclude some 5% of users. However, iOS does BLE in it's own unique 'designed in California' way.
We should also take note of the success of South Korea at fighting the spread of the virus as their contact tracking is a mix of GPS, cell tower triangulation and bank transaction analysis. Basically, throw away your electronics and pay cash.
Someone:
--- Quote from: SparkyFX on May 13, 2020, 07:21:45 pm ---(Near) Ultrasound/Sonar would circumvent the problems with EM-reception field strength indication vs. physical contact, but most people carry their phone in pockets, introducing lots of noise and dampening, making a distance measurement hard.
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There are a non-trivial number of people who carry their phones in a bag. Pocket locations/sizes/availability don't always match phones. Bluetooth was the best of the options already in place and ready to use.
--- Quote from: SparkyFX on May 13, 2020, 07:21:45 pm ---This is why I think the approach to trace contacts and possible infections via smartphone is ill-fated, i doubt there is an advantage over the regional physical distancing rules indicated by test/amount of newly infected people. It would take time to crunch the data, make the decision and will probably affect as many people as to locally check by infection rate if measures for a whole area are needed. Both methods just follow what this virus is doing, but given the long incubation time only preventative methods could make an impact.
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There are good motivations for digitally enhanced contact tracing, partly that peoples memory is really unreliable. Being able to reliably know where someone was during the period they might have been infectious is valuable alone. But when that location information is then cross-referenced against other people a so they are notified with little effort on their part, its a possible game changer.
The main justification for such an automated system is that you can reduce broad "sledgehammer" measures like arbitrary travel constraints (border straddling towns for instance. Instead focus on just the people who have higher likelihood of having caught the virus. We've already seen this sort of thing by applying additional restrictions to travellers coming across borders. That has its problems, trying to convince a subset of the community that they need to undertake an individual quarantine/isolation while 99% of people continue with their daily lives has been a hard sell already:
https://www.abc.net.au/news/2020-04-15/man-jailed-for-breaching-coronavirus-quarantine-by-leaving-hotel/12149908
Imagine instead of being arbitrarily quarantined, travellers were only segregated if they were within [arbitrary measure of infectious distance/trave] of confirmed cases. And such restrictions could be applied to individuals retroactively, after discovering new applicable cases. That could be a big win for the vast majority of the population. Keep up the physical distancing etc, and people who do that will be less likely to have restrictions placed on them individually. Its handing back control to the individuals, but both sides need to have a trusted system in the middle to mediate it.
cdev:
But when people are outside, there is virtually no chance of infection, and as I was trying to explain, when people are indoors the locations reported and saved to logs are invariably wrong. They are not accurate indoors. Most dangerous encounters are not in RF transparent buildings. They are in big buildings (work) or underground, neither of which is a good environment for location capture. Dont believe me? Look into "SLAM" on github.
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