The Mr. Beacon Podcast: The origin & technology of Forkbeard

Forkbeard’s CTO Wilfred Booij was recently interviewed on the Mr. Beacon Podcast about the company’s origin and ultrasound indoor positioning technology. From dining with Stephen Hawking during his PhD at Cambridge to Forkbeard’s technology bringing the GPS revolution indoors, the topics were wide ranging. Below you will find a summary of the key questions posed by the host Steve Statler and our Wilfred Boij’s answers. In case you would like to listen to the whole podcast, you can do that here.

Questions and Answers were paraphrased and supplemented with additional information for clarity and summary purposes.

How did Forkbeard originate?

In January 2019 Forkbeard was spun out of Sonitor which has been focusing on indoor positioning systems (IPS) in the healthcare market for over 20 years. Sonitor uses Bluetooth Low Energy and ultrasound beacons and tags to achieve high zone accuracy (e.g. notify staff if a patient has left his bed). For this to work, Sonitor installs the beacons in a way that corresponds to the zones relevant to a use case (e.g. patient’s bed). The dream was always to decouple infrastructure from use cases and move towards software-defined zones. This would mean that regardless of where and how you installed the infrastructure you can draw an arbitrary number of zones afterwards.

To realize this solution Forkbeard started to develop an accurate, low latency and persuasive 3D positioning system leveraging Bluetooth® and ultrasound waves. In the process of building this solution Forkbeard also replaced tags with smartphones since most people carry those around already.

Can you tell me more about your beacons that you sell and how many you typically need to do indoor positioning?

Our beacons emit Bluetooth Low Energy and ultrasound signals. Based on our previous experience in healthcare at Sonitor, we really focused on engineering our beacons to be as robust as possible. Therefore, they are the size of an Apple TV box, run on 4 AA batteries and last approximately 10 years on a standard configuration.

The beacons are the only hardware our customers really need to buy. We price our installations per square meter and the ultraBeacon itself is not really expensive.

The quantity you need always depends on how fragmented the space is in which you are trying to do indoor positioning, but the minimum requirement for 3D indoor positioning is 3 beacons. For installations in larger spaces it usually translates to one beacon for every 30m2.

Ok, if I would use 1 beacon for every 30m2, what would be the accuracy that I can expect?

For 2D, X and Y dimension, we have an accuracy of one foot (30cm) and for the height, or Z dimension, we are about two feet (60cm) accurate.

Positioning you against other technologies you are much better than Bluetooth® alone, slightly better than angle of arrival and not quite as good as ultra-wideband. Would that be a fair categorization?

Yes, that would be quite accurate. And then we have the advantage of a fully battery powered infrastructure. This makes a big difference when it comes to installation and running costs.  

Why did you go for ultrasound?

So the concept for indoor positioning is similar to how we humans can see anything in the world: sun light is reflected from objects and is captured by our eyes. Now to accurately see and locate something we need to have direct ‘line of sight’ which is to see the object unobstructed by any other objects. This is the same principle that IPS solutions use.

With conventional indoor positioning systems, radio waves such as  Bluetooth®, are reflected from objects and we can then estimate their distance and location. However, the problem of radio waves is that the signals are not perfectly reflected back from the objects due to many reasons (e.g. wave backscattering, absorption, etc.).

In contrast to this, ultrasound is nothing more than a pressure wave and perfectly gets reflected most of the time it hits a surface. Therefore, the reflections can be aggregated and reconstructed into a very accurate indoor position via path decomposition. This method is so powerful that in the future we are looking to do the positioning only with one beacon instead of three that are usually required.

You mentioned that you also use Bluetooth® in your solution. Do you combine that with ultrasound?

Yes, we do use Bluetooth® in combination with ultrasound. The great advantage of ultrasound is that you can do very reliable path decomposition and distance measurements, but the bandwidth is very limited, especially on the phone. The ultrasound range for the phone is between 20KHz and 22KHz which is quite small. This means that in larger crowds where many people are accessing our solution, ultrasound signals will not be unique enough to distinguish between individuals. That is where  Bluetooth® signals come in. We use a combination of  Bluetooth® and ultrasound to give enough uniqueness to our signals and increase the bandwidth.

This also allows us to improve distance measurements, similar to how you measure a thunder storm based on light and sound:  Bluetooth® signals are the lightning travelling at high speed, while ultrasound is the thunder travelling at slower speeds. Similar to a thunderstorm, you can estimate its distance by calculating the time difference between the lightning and sound.

Can you quantify the accuracy of time? Will there be a difference in positioning between sprinting or walking casually through a shopping mall?

We typically have 5 to 10 updates per second. We leverage the high frequency of updates and the Doppler effect to get a sense of direction instantaneously. More specifically, we can calculate velocity of distance, of the phone, the main path and even all paths that we receive signals from. This means that we are able to measure very accurately engagement metrics for point of sale promotions. For example, in addition to how many people have walked passed a shop, we can also tell you at what speeds and who stopped for a few seconds to look at a product.

Do you have an app or how do you consume this technology? And I assume you would need to have the app in the foreground?

We have the Forkbeard app in the App Store and Google Play Store. This app is mostly for demo purposes to show how powerful the technology is. And both operating systems allow you to use sound in the background, so we do not need the application being run in the foreground.  Regarding privacy, we are GDPR compliant and achieve privacy via consent by the users who download and use the app.

However, our main objective is to allow other developers to fill in the blanks in the indoor positioning space. Therefore, we have created the Phone-FUEL SDK that contains multiple APIs, similar to GPS, which can be integrated with common operating systems. Developers usually need one to two days to have it implemented in an app.

Now let’s get to the interesting questions. I have to ask about the name. Where does the name Forkbeard come from?

We wanted to find a name that was meaningful and reflected our Nordic heritage. As some know, the Bluetooth® technology originated from the Nordics and was given its name after a famous Danish & Norwegian king (Harald Bluetooth). He was, going by the history books, very good at communicating and connecting people. So when we were thinking about the naming of our company which uses Bluetooth® technology but expands its capability with ultrasound, we wanted to find a historic figure that superseded king Harald Bluetooth. And fortunately for us, his son named Sweyn Forkbeard not only succeeded his father, but also was an exceptional navigator.

And one last question. I see you did your PhD at Cambridge, how was that?

That was a wonderful time. Quite an international environment where I met my Norwegian wife which is also the reason why I ended up in Norway. I also had the pleasure to be a fellow of one of the oldest colleges there, the Gonville and Caius College. And since Stephen Hawking was also a fellow at the same college during my time, we practically lived right next door and I had the opportunity to dine with him on a few occasions. So yes, a lot of interesting experiences. And of course, a good variety of very old wines that I got to try.

You can find the whole interview here.

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