Avatar for Mi


Member since Dec 2021 • Last active Jun 2024
  • 2 conversations

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  • in Bangle.js
    Avatar for Mi

    Range might be maximum measurable values, maybe with a tradeoff with regard to precision for the higher values.

    Exactly. That is in g, so in the picture set to 2g.

  • in Bangle.js
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    I just tried the nRF Toolbox for bluetooth LE. I was able to get HR, but nothing else

    That will work after sending one message to initialize the stream. Afterwards all the data is send just like HR. That is oficially documented. See here for SDK https://github.com/polarofficial/polar-b­le-sdk

    As said I did this in a python program some time ago and it was pretty straight forward. Was just a few lines. For someone familiar handling blluetooth on bangle that should be very easy.
    If someone wants to try, I'll go try to find my old python program.
    Or maybe just look around on the net, I am pretty sure I am not the only one that did that.
    Maybe there is already js code.

  • in Bangle.js
    Avatar for Mi

    Do you have an Android device? Try "Polar Sensor Logger"!.
    As far as I know not an official app, but one written by a polar employee privately.
    Its an easy small app that connects with the H10,

    • can show all incoming sensor data graphically (HR, ECG, Acc)
    • can record that data
    • write the recording to a text file (that you can analyse, probably even with excel)
  • in Bangle.js
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    And one more thought: don't hold yourself back if you not have a chest belt yet.
    There is a good chance the data is so clear with bangle close to foot that no reference is needed anyway.

  • in Bangle.js
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    I grabbed .fit files from the Fenix5 and also from a forerunner 235, really easy, no cloud needed, no softwares to install.

    Very interesting. Thanks for the information.
    Maybe I try to get one of those second hand also. Will check their capabilities.

  • in Bangle.js
    Avatar for Mi

    Polar H10, as it seems it's going to provide the needed data, but if someone has other suggestions, I'm all ears.

    I do use the H10 all the time and can really recommend it. Works with bangle and "Bluetooth heart rate monitor" out of the box for HR much more reliable than the optical sensor in bangle.
    As said I got acceleration and also a very good Electrocardiogram (much more detailed heart information) via python and it should not be difficult to get this into bangle since it is broadcast in the same as HR or HRV (there is also an app for HRV) after initialization.

  • in Bangle.js
    Avatar for Mi

    Time is also limited here, but I certainly can give you some guidance.
    I did use the H10 SDK in the past. It was very easy to get acceleration, HR, ECG.
    More advanced features I did not get to work in limited time although that should also be doable.
    Eg. start/stop/download the internal memory which can record some 24h HR on its own without smartphone. (Anyone has JS or python code for that? I would be interested)

    I will just extract the .fit files from the watch and use them in Golden Cheetah, to keep privacy

    Did you manage to do that? Get the interesting information out of garmin watch without cloud?
    I gave up on suunto watches because that was not possible anymore at the time.

    but not running dynamics. This only comes if using a compatible chest strap with an accelerometer

    Do you have such a compatible chest strap? Then you can wear garmin in your experiments and produce a fit file as "ground truth" reference for the information you finally want to extract from the bangle sensor. Such reference helps a lot in development.

  • in Bangle.js
    Avatar for Mi

    Good, keep us up to date about your findings.

    Next idea: Another bangle (eg. if you have a bangle 1 laying around) strapped to the ankle could do the trick also instead of a puck. And there is already SW to record the ACC data for first tests.
    So for a very first test you could just use the bangle you have, strap it to the ankle, record ACC data with recorder ( don`t know what frequency is available and necessary. I guess you want at least 5-10 measurements per step) and visualize the result (if you are not a programmer, excel will do at first).
    I would assume the time of contact is very clearly visible and the acceleration in forward swing has a clear correlation to stride length - which could even be calculated pretty accurately with a biomechanical model (big word for simple thing given that only two 2d joints are really involved at any given time)

  • in Bangle.js
    Avatar for Mi

    Reflecting a bit on my last post: there is the puck which has ACC. I think it should be pretty easy to replicate something like the suunto foot pod.
    So if you are willing to attach a puck to your running/cycling shoe, that still would need some programming, but of the simple sort.

  • in Bangle.js
    Avatar for Mi

    the accelerometer might be the only sensor needed to get all the other data that I'm interested in

    Correct, but there needs to be software to convert the raw sensor signals to what you want. If that is done in the garmin watch, you cant use it for bangle. And if nobody writes that for H10 your out of luck also, even if all you need is implicit in the raw signal - but you need it explicit.

    To get a desired information its important what sensor, where placed and how processed.
    With the right sensor at the right place processing can be near trivial, otherwise difficult or impossible.
    For HR or HRV measuring electrical signals near the heart (what the chest belt does) gives very accurate and very easy to process signals and is not very sensitive to movement. In contrast Optical measurements at the wirst (PPG) is pretty difficult to interpret and very sensitive to movement. Which is why bthrm is much more reliable in principle, not only because of difference in software sophistication.
    Now to acceleration data. The more direct to the source of movement it is connected, the better the results, the simpler the software can be. I used to have a suunto footpod attached to the shoe. There foot contact is near trivial to detect and very precise, as would cyling frequency and the like have been. Compare in contrast the movement of your wrist, which is decoupled from the foot by a large number of joints, so to measure those things with bangle directly (which has ACC) would be at least very involved, maybe impossible.
    Chest is somewhere in the middle here, but if you are not a beginner and running/cycling smooth I guess your hip does a lot of decoupling.
    What does that mean? Golden Cheetah (great program, used it in the past together with TACX data) will not do the trick alone - except garmin does the calculations in the chest belt, possible but I doubt it, and sends the results in a documented format over BT characteristics, again possible but I doubt it.
    If you can find a documentation about what the garmin sensor does send over bluetooth characteristics or even better a github repository with example code, that would be great. Otherwise you probably need to assume you can't use those features, maybe not even have access to the raw ACC data as we know the H10 provides. You also can try to find a github with open source code to extract what you want from H10 data.
    If you have found one of those I can help to make it work together with bangle or Cheetah.