Webinar contact tracing apps

Demystifying contact tracing apps - webinar

Why is Bluetooth proximity detection harder than people thought? What are the fixes, the alternative approaches, the best architectures? Our Founder-CEO, Dr Ramsey Faragher explains all during this webinar hosted by the Royal Institute of Navigation.

In this webinar, Ramsey gives an overview of:

  • What contact tracing is and how bluetooth low energy works
  • Why it went wrong first time
  • Why it went wrong a second time
  • Why it's still going wrong...
  • How do we fix the situation

Traditional Contact Tracing

Contract Tracing 2 01

00:54 Ramsey explains the traditional aka manual contact tracing process

Traditional human contact tracing is a deep piece of detective work that in the past has relied on good knowledge of where people have been and as much information as they can provide on who they've been with as well.

Digital contact tracing opened provided an opportunity

  • your smartphone can keep a log of where you've been
  • phones can talk to each other in the background
  • they can share ids and therefore keep a log themselves as to which of the phones they've been near and when

However...privacy is something that is naturally counter to contact tracing. Introducing battle number 1.

BBC contact tracing model

04:13 in, Ramsey talks about the pro's and cons for centralised vs decentralised privacy

The key difference between those two is whether the information is being managed, stored and passed through some central location (like a server within the NHS here in the UK) or a decentralized version where the only central point of contact that the smartphones communicate with is a simple rerouting service that passes messages between the phones (which doesn't actually store anything).

In April 2020 Google and Apple announced a partnership which would see them support with contact tracing challenges....

Apple google partner on covid 19 contact tracing technology 04102020 inline jpg large

Shortly thereafter, we saw battle 2 underway. Here's Matt Hancock on the 18th June explaining the problem.

“So as it stands, our app won’t work because Apple won’t change their system, but it [the NHS app] can measure distance and their app can’t measure distance well enough to a standard that we are satisfied with.” Matt Hancock - UK Health Secretary

Big bags of salty water

09:20 mins in, Ramsey highlights a major problem regarding radio signal strengths being impacted by 'big bags of salty water' aka human bodies. Putting a body in the way of your smartphone adds about 10 meters to the apparent distance so you can be stood half a meter from somebody but the phone behind your back, thus the contact tracing app, will think that you are now 10 meters away.

For those wanting a technical overview of signal strength, wavelength and variations in multipath interference, checkout the video between 11:00mins to 32:00 mins which sees Ramsey deep dive into the tech.

In summary

We have this great spread of of countries that are choosing to use different technologies; some are using the new protocol, some are sing bluetooth but not the new protocol. Clearly, there is still plenty of work left to tackle in this space.

1) Hopefully the the Google Apple explosion notification protocol will steadily improve - one of the biggest challenges is basically understanding what the internal priorities of a large company is Vs what other entities priorities might be because we will inevitably always have this clash.

2) It's obvious to anyone that's ever worked in location sensor fusion that you you must combine various sensor technologies to get the best possible performance from a contact tracing app

3) We believe the choice should be down to end users
- provide the end users the rights to decide what they want their trade-offs to be between privacy and battery life and the well-being of themselves and their loved ones.

For further reading on contact tracing apps, take a look at Ramsey's Forbes column here.