Accurate running speed - gps v footpod

Hi! It's worth checking the Bangle had a minute or two to get enough GPS satellites for tracking - if you turn it on and start running immediately, the first few minutes it won't have many satellites, and as it gets more and gets more accurate the position it reports will fluctuate.

I should be able to connect a polar h10 chest strap to the bangle without problem, right?

Yes, absolutely. You just need the bthrm app

Is there any software solution to get a speed on the gps that fluctuates less?

You could for instance store the last 10 GPS values (which occur every second) and then divide the distance between the current position and the one 10 seconds ago by the timestamp between them... Or either average the 10 instantaneous 'speed' values or do a median filter?

There is something called 'kalman filter' that can be used to filter GPS coordinates/speed, and there was a running app that did use it for a while but unfortunately it got broken and wasn't maintained so it's not there any more - but if someone could figure out a way to re-add the code, it might be a really cool addition.

If you seriously want to dig into this, it might be worth setting the recorder to record at 1s intervals (in which case it'll record everything), and then you could go back over it on your PC and see if different algorithms provide better values.

footpods specifically designed to measure a host of running data

I think @Fteacher may have been asking about this before, but I'm not sure anything came of it. I think for some of these they basically just stream the accelerometer data to a phone and get the phone to do the analysis, so it may not work to connect them to a Bangle.

Is a puckjs accurate enough to measure the length of a step while running?

In terms of accuracy it'll be fine - it's probably got the same exact sensor as the Sryd. It's just what you do with that data that matters :)

For instance if the Puck is worn on your ankle then it might twist slightly as you start and stop, the stride, which will mess with the readings - and to work around that you'd have to do proper sensor fusion to use the gyro to also work out its angle so it can apply the acceleration in the right direction - and things get a lot more tricky.

If you can be reasonably sure the sensor is only accelerating and de-accelerating in the same direction each time (which is perpendicular to the earth so you don't have to worry about gravity) then it shouldn't be too hard though.

Potentially even if it isn't 100% accurate, when calibrated against your actual speed from GPS when you're going at a steady speed, it could allow you to get far more responsive values.

If all you care about is the accelerometer, you could actually just use your Bangle on your foot as well :) Although I admit that's not idea for also allowing you to look at speed.