Hi Steve,

You probably have read more on this already than I have, but I believe the 
reason for using sound rather than bluetooth is that RF can see through walls, 
and very high-frequency sound can’t.  They wanted a signal that would be 
positive for people in the same interior space, but not for people who were on 
opposite sides of a wall through which there wouldn’t be air connection.  

I forget where I got that, possibly from the company’s site, though several 
months ago.

Or did I misunderstand the subject you meant?

Thx,

E


> On Dec 15, 2020, at 5:43 PM, Steve Smith <[email protected]> wrote:
> 
> Eric -
> 
> Great story/shout-out to those who create/maintained a "pocket of sanity" for 
> you.  I feel similarly with the Los Alamos County swimming pool which manages 
> to be hyper-welcoming whilst managing things in a convincingly safe manner 
> (w/o seeming arbitrary?).   It helps that there is chlorinated water 
> everywhere, though I don't know the relevant concentrations in this case...   
> 
> Also fascinating that it uses hypersonic audio (mic and speaker) to exchange 
> "public keys".  I have a camera/app that does this but in the audible 
> spectrum which is vaguely annoying.   In the camera case it works a bit like 
> a two-factor authentication, or an ID-free bootstrapping.   I think the 
> camera starts by chattering gibberish that the app hears and recognizes as 
> "one of it's own" which then triggers the app or camera to reach out over 
> wifi and make a connection there.   I have a few tone generator apps and an 
> oscilliscope app which samples the headphone/mic input... I'm guessing I 
> could kludge a simple NOVID detector and even do some kind of reverse 
> engineering of it?   I don't see any particular reason that an audio 
> "detection" is better than a BT one excepting maybe that the latter can be 
> power hungry (compared to a frequent ultrasonic chirp? or that the BT apps 
> use BT:MAC addresses at some level (implying less privacy)?
> 
> I'm mildly disturbed by the implications of a hypersonic "dogwhistle" app, 
> though current low-tech modes of signaling one's proclivities and loyalties 
> is plenty effective (Mason's rings, secret handshakes, code words, etc.)
> 
> Next thing we'll all be putting bandaids over our microphones on our devices?
> 
> - Steve
> 
> 
> 
> On 12/15/20 12:14 PM, David Eric Smith wrote:
>> Yes, seems to be a good app.
>> 
>> Georgia Tech has set up a group account that one can log into, and it is 
>> part of their campus surveillance system.
>> 
>> I do have to stop, and do something probably nobody on the list has any 
>> reason to care about, to give a shout-out to them.  The current GT 
>> monitoring system was designed, I think mostly if not entirely, by a young 
>> biophysics faculty (Josh Weitz) working with the department head (Greg 
>> Gibson).  Since early in the year, maybe April or May, they have had a 
>> streamlined testing pipeline, and their target (which I think they mostly 
>> approach) is to test the entire on-campus community weekly.  Their 
>> positivity return rate during the summer was around 0.3% for a couple of 
>> months; in the autumn it climbed back up through 0.7% and toward a percent, 
>> and the messages and exhortations started to come in fast and thick.  All 
>> that went together with refitting many buildings, including the old biology 
>> building where my office is, built in the middle Stone Age, with HEPA 
>> filters and UV irradiators in the HVAC ducts, occupancy protocols, and 
>> various else.  Certainly the effort involved was enormous work from a large 
>> number of people, and the two main guys were mainly designers and 
>> participants in the choreography.  But overall it has had the feeling of a 
>> pocket of sanity and good practice that would have been in place in any 
>> number of civilized countries in the Eastern hemisphere.  With the expected 
>> results of providing mostly excellent protection for a community of people.  
>> And that, for a state school.
>> 
>> I do not know (have asked a CDC epidemiologist friend, who also doesn’t 
>> know) how much efficacy data has been compiled for NOVID-using communities: 
>> that is; what fraction of cases that would have escaped to potentially 
>> transmit, did they catch and get safely into a quarantine before anybody 
>> else was exposed?  Iceland did a great job of that with manual contact 
>> tracing back in the earliest days.  The real figure of merit for         
>> NOVID will be how much of that effect it can contribute through a 
>> decentralized computer app, which at least offers better scaling cost than 
>> manual contact tracing once the distribution is wide.  If somebody on the 
>> list finds good data on that, I would be interested to know.
>> 
>> Eric
>> 
>> 
>> 
>>> On Dec 15, 2020, at 1:12 PM, Tom Johnson <[email protected] 
>>> <mailto:[email protected]>> wrote:
>>> 
>>> NOVID is the first pre-exposure notification app to fight COVID-19. It’s 
>>> free, anonymous, and shows you cases close in your network before you’re 
>>> exposed. It only takes one minute to download. Please visit novid.org 
>>> <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fnovid.org&c=E,1,VwlMJTw8gqSVqbo2jJiXmT5NM5NAq_5yttP-l2lMZNpp2VMc6PbSqDKtDArm04wXuOsKAwniiJ1YmGYvBupyCA7hDVU8uZl6NwnstOOkPcPVwTSWJKXWKZ6Q6A,,&typo=1>
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