Apple GPS Thoughts

UWB the GPS of indoors ?

In respect to mobile phone usage I swing both ways so to say, my “work” phone is usually the latest Android device, currently a Pixel 5a (5g) and my “home” phone is an iPhone.

I have been sitting out iPhone updates for the last few years, happy with my 2017 iPhone X, but this year some of the new “Geogeek” features on the new iPhone 12 Pro have had me reaching for the Amex card !

Clearly the LIDAR capability is a technological leap forward bringing the capability to map indoors and undertake SLAM based navigation could at last bring progress to the challenging business of bringing consumer mapping indoors, somewhere we spend at least 80% of our lives (even more so during COVID ?).

This technological leap forward taking a capability that previously costs tens of thousands of dollars into a phone comes once again from the integration of complex electronics onto dedicated chips in this case a VCSEL (Vertical Cavity Surface Emitting Laser).

The image of my desk above was generated combining the camera and LIDAR sensor of my new iPhone in around a minute !

Another dedicated chip in the new iPhone is perhaps even more interesting but less obvious at first

Another dedicated chip in the new iPhone is perhaps even more interesting but less obvious at first. Apple have been developing their own “U1” chip for a few years, it’s name is a big clue to its role, it is responsible for Ultra Wideband or UWB communications.

UWB may be used for personal area network communications, allowing devices such as phones and remote controls to communicate with each other and nearby devices, so there is a lot of crossover with the more well known Bluetooth protocol. However, there is big difference in how UWB operates that means it can offer some more functionality that is very useful for location determination and familiar if you know anything about how GPS works.

UWB is a pulse-based system, one that repeatedly blasts out signals then turns off before repeating, by regularly sending out a pulse of data, it can enable other nearby devices to know it exists, or vice versa if it receives a pulse from another device. This is clearly beneficial for proximity sensing applications such as contact tracing which have been problematic with Bluetooth.

Because UWB uses a wide range of frequencies it enables devices to more robustly perform Time of Flight (ToF) calculations, estimating as does GPS how far apart the devices are located.

Any system based on Time of Flight calculations have to deal with multi-path propagation where radio waves take multiple paths to reach a destination, by using multiple frequencies a more accurate calculation is possible.

UWB tracking applications have been used for a number of years in high end engineering applications, for example Airbus used a UWB system developed by Ubisense to prevent tools ending up inside sealed airliner fuel tanks !

Devices communicating with each other using UWB can apply timestamps for receiving and sending packets, allowing the calculation of relative distance between them with some accuracy but in addition it is also possible for UWB radios to determine the angle of an inbound signal, determining a direction the device is located in relation to it.

Time and bearing measurements should allow relative position down to a few centimetres and of course these can be anchored if one of the devices has a known fixed location in space.

What does this all mean?

Well potentially in your pocket you now have one device which solves both the problems of location determination and capture indoors !

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