[chbot] Bluetooth tags

Stephen Irons stephen at irons.nz
Thu Oct 1 00:53:09 BST 2020

Some weeks ago, we spoke about Covid tracking and using Bluetooth tags. 
I wondered about what would happen if there were many tags in a close 

I had the opportunity to set up a test, and now have some actual data.
104 devices operating as BLE beacons, transmitting an iBeacon-format 
signal every 1.5 sCR2032 battery, plastic housingall bundled together 
in a plastic bagmy PC with a USB BT adaptor acting as a monitorusing 
Python 'beacontools' to monitor beaconswith a filter to receive only 
the BT address prefix that I am interested in
In 20 scans, the monitor has heard all tags, every time.It takes ~100 
ms for the system to report the first tag.It takes 8--10 seconds for 
the system to report up all 104 tags.In 60 s of scanning, each device 
is heard an average of 22.8 times. Each device transmit 60/1.5 = 40 
times, so we hear just over 50% of the transmissions.
I know that there are other BLE beacons in the area, as well as many 
WiFi networks, BT phones, headphones, TVs, etc in the vicinity.

The system works better than I imagined it would...

Stephen Irons

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