Trustful Devices

Written by
Matthias Wagler
23 Juli 2014

„All the world is made of faith, and trust, and pixie dust.“

J.M. Barrie, Peter Pan

Every solid and long lasting relationship requires a certain amount of trust. The high number of technological touch points in our daily lives are asking for it. In case of safety related assistants, trust is a key factor for effectivity.

The inner circle of trust

When Markus, Steffen and Stefan visited us in Hamburg early this year, they experienced a situation that may sound familiar to you: during the night in an unknown hotel, the fire alarm started to ring. Like many of us would do, their first reaction was to question the accuracy of the device. They decided to ignore it.

Since the alarm went on, it was time for them to dress up (just in case the alarm is reasonable). From that point on, things were changing. It’s the fine line between believe and doubt which – in cases like this – gets pushed in either one or another direction. In my opinion, this problem is caused by a lack of information. The device has one, single minded job (making noise), but provides no contextual information. It’s like trying to have a conversation with somebody without having the same vocabulary in mind. Obviously, smoke detectors are not devices we elect to be part of our „inner circle of trust“.

Introducing „The EMP“ (Emergency Protocol)

With this situation in mind, we started to challenge this problem. The initial question was: how can we boost the trust of a simple smoke detector to make it work even in unknown environments. Smartphones are a good example for trusted devices. They are a close part of our daily life – we carry them from A to B, protect them in cases, we share intimate moments and thoughts, socialize with friends and family – and we are very familiar with the user interface design. Therefore our smartphones or tablets are the perfect carrier to decrease the circle of untrusted devices.

Technically there are many ways to pair devices like WPS, WPA-Secrets or simple number-codes. But in this case non of these solutions would fit since nobody would take the time to pair devices for every new location. The solution had to be so simple, that no user even had to think about pairing. So how about using the alarm-tone to transmit data? Boris Smus wrote a great article on how to transmit simple data by using ultrasonic sounds utilizing the Web Audio API. With this approach in mind, we gave it a try: Test-01 The HTML prototype worked out quite stable and reliable. We modified the Audio API to listen to the frequency of about 3450 Hz generated by the smoke detector. With this little trick, it was possible to use this solution without modifying the smoke detectors hardware. At the moment it is not possible to wake up the operating system by sending tones – since this is not the idea of the Web Audio API. Nevertheless, it’s important to react to such important events not only by sending alarm-tones but also by guiding the user visually.

With the introduction of the „Emergency Protocol“ we could establish a simple solution for devices to communicate without pairing. This function could be implemented as part of todays phones emergency menu.


This prototype had the intention to start thinking about the usage of devices in terms of trust and reliability. Technically we already see some phone-device implementations such as Nest but always including a process of device-pairing activities. Feel free to share your thoughts on our approach!