Currently many sports devices use GPS for positioning. There are a constellation of up to 31/32 GPS satellites at any one time doing their thing. Not all are operational at any one time.
GPS is the name specifically for the American positioning system.
It’s fairly hard to get GPS accuracy below 5m, indeed the precision of GPS is 5m, and hence working out how fast you are going and exactly where you are is difficult. But, add in a runner’s footpod or a cyclist’s wheel-based speed sensor and you can get your speed/pace more accurately defined.
I’d argue that, with a decent hardware implementation, the GPS method of working out speed/pace has been good enough for most people, most of the time.
However for navigational purposes some athletes REALLY need to know CONFIDENTLY and EXACTLY where they are.
Imagine a tiny little antenna bouncing about as you run. All the swinging and bouncing when you run is HARD to keep track of. Even harder when you hide the antenna by earing the watch the ‘wrong way around’. It’s easier when cycling to keep track, but hard when running.
Further imagine a shoddy little GPS sports watch where all the bits have been thrown together with no electromagnetic shielding and with components touching each other.
Electrical Interference = Bad. ‘Design & Tuning’ = Good.
If you further imagine the 31/32 GPS satellites going round the Earth, then clearly your watch/device can’t see them all as many will always be over the horizon. If a building temporarily gets in the way it can see less of the satellites and trees & other obstructions can cause problems too. So maybe in a real-world scenario you could be reduced to line of sight access to only 4 or 5 satellites. Potential accuracy will most likely suffer.
BUT. The Russians also have a satellite navigational system called GLONASS. Essentially it’s the same kind of thing as GPS but with 24/7 satellites and a level of precision/accuracy between 4.5m and 7.5m
So, simplistically, there are now more satellites to have a better stab at working out where you are.
OK you already knew that, I know.
I don’t think many of us have seen any increase in the precision of GPS+GLONASS. ie it does not appear to be telling us where we are to within an accuracy of, say, 4m rather than 5m. What it might have done is increase the chance that a location could still be established when line of sight to a GPS satellite is lost. So a forest runner may notice a difference more than a road cyclist.
The Europeans belatedly want to get in on the act too, possibly because the Americans and Russians can simply turn off their systems if they wanted to (and yes I know the Americans have said they won’t).
So we have the GALILEO ‘constellation’ of satellites. Most of them should be in orbit by the end of 2017 and operational by 2020. They will comprise 24 operational satellites (out of 30) but critically they are touted to give a PUBLIC level of precision to 1m and the possibility of encrypted accuracy down to 1cm (centimetre!).
Of course the Chinese, being a global power, have to have one as well. That’s the snappily named BeiDou system (BDS). Again we are looking at 2020 for a global system from them and their system comprises 21 satellites (out of 35) but their public accuracy is planned to be 5m although encrypted accuracy will be 10cm.
India are also working on their version called IRNSS but that looks like being a low-altitude regional system rather than global, so that’s little use to us.
What seems to have been happening over the last few years is that the manufacturers are taking hardware shortcuts and trying to compensate with firmware fixes to ‘average’ or ‘predict’ positions. Possibly that is at least part of the explanation why you might think that the new tech seems to be performing worse than the old tech you used to have. (Or you’re getting older and your memory is fading like me!)
Delivering 1m Precision
However GALILEO, in itself, won’t give all the precision gains many would like. A high quality chip AND electronic design is also needed.
One of the high quality (expensive) chips to watch out for is the XTAL chip.
The constellations have different altitudes and different frequencies of signal, presumably different encryptions as well. Nevertheless chips already exist that can read all the constellations.
No doubt more battery power will be needed to process 3/4 lots of signals…
Delivering Altitude Precision
So, come 2021 will your Fenix 6 have a quad-constellation receiver (GPS, GLONASS, GALILEO, BDS) and super accuracy to the nearest metre? Maybe! Maybe even more precise if the design is good enough.
Even improving current precision levels by a couple of metres opens up the prospect of notably better GPS-estimated altitude as well as location. The distance from you to the various satellites can also be used to determine altitude – this is already used on many GPS sports devices.
Other sports devices use a barometer to measure pressure changes to estimate altitude/ascent/descent changes.
Yet other devices, TomTom and Suunto for example, combine or FUSE both methods.
These methods are all going to have the potential to get more accurate.
My personal belief is that, just like we currently get a-GPS (assisted GPS), quick satellite fixes by predicting satellite locations then so shall we also get precise altitude figures pre-loaded for known GPS locations. For example your Suunto might know your home/POI GPS location and ALWAYS will AUTOMATICALLY recalibrate based on that known and fixed altitude at the POI. You could also see how downloading a course/route to your sports watch could also quite easily download various altitudes along the route. [Here’s where you tell me all he wonderful SPORTS devices that can already do that 🙂 ]. You could also see that, as well as storing routes and maps, the space cost of an altitude database on your watch will also add a space and processing cost.
So, the technology is probably ‘there or thereabouts’ right now. The limiter will be the sports watch manufacturers who might determine that not enough of us will be willing to pay for the increased costs of delivering increased accuracy.