Avatar for Mi


Member since Dec 2021 • Last active Jul 2023
  • 2 conversations

Most recent activity

  • in Bangle.js
    Avatar for Mi

    Unless we saved the key on the watch ... but I'm a little out of ideas.

    What about storing the key only in RAM and only when connected to the phone?
    So the phone stores and provides the key. Shortly after they get separated the key is deleted on the watch. As soon as they are close by again the phone provides the key to the watch again.
    This assumes that you only need to watch=decode the data while you have your phone with you. Going to a run and storing=encoding data could be done without phone still using asymmetric keys.

    That should be safe as long as the phone is not stolen together with the watch .

  • in Bangle.js
    Avatar for Mi

    I had this often in the beginning, then not at all for the last year or so (Don't really remember if I did something to fix and what or it just vanished with some firmware).
    Recently I was surprised to see it back, but only once so far. So I ignored for now.

  • in Bangle.js
    Avatar for Mi

    Ah, ok, interesting, thanks!
    So looks like I am in that low curvature regime all the time indeed.
    (There were lower temperatures outside, but wearing bangle it probably still stayed above 20°)

  • in Bangle.js
    Avatar for Mi

    Wanted to share the following observation and ask maybe other users to share their ppm value.

    • Its about two bangle2 from kickstarter.
    • On my watch I did set the time beginning of May and noted the deviation about every week. There were rainy cold weeks and very warm ones like the last. Sometimes I did wear the watch all the time, other times not for several days.
    • For the watch of my wife I measured the deviation since a good week ago.

    To my surprise all deviations were about 70 (+-2)ppm!
    So maybe temperature has not such a big influence?
    Is it a coincidence that the two watches do have such a similar constant - or were might this systematic deviation stem from? (which after all makes about a whole minute every 10 days)

    And thanks for that widget. With so constant deviation we are looking forward to a pretty exact watch time in the future :-)

  • in Bangle.js
    Avatar for Mi

    Thanks a lot!

    • Indeed, download with app loader worked immediately (wasn't aware of that option, always used IDE so far)
    • Also 0.27 works as intended. Possible reason why it didn't before: number was at 5 and I manually increased it to 6 before start recording (see next point). So it used that. Looks like you set the date filename with the new button after you detect a conflict?
    • Could this conflict menu made optional somehow? I personally never have used the Overwrite/Append/No, so its always "new". Besides the extra tap I always am a bit afraid to accidentally overwrite/append given the small buttons. So I typically manually increased the number before start (some more taps). With the date format I was hoping to get rid of that fear and taps - just start recorder with one tap.
    • If this is only me interested in or difficult: don't mind. I plan start/stop recorder from within a watch face/own app anyway and saw I can force new in the api, so should be fine

      WIDGETS["recorder"].setRecording(true, {force:"new"/"append"/"overwrite")

      Pretty happy to get dates instead of numbers here.

  • in Bangle.js
    Avatar for Mi

    -How do I activate this?
    I installed recorder 0.26 (seems to be the same on dev and regular in the meantime, dev doesn`t offer update), and did a recording. Came out as numbered.
    Do all numbered recordings need be deleted?
    I do have one still on the watch that IDE doesn't manage to download (it was the longest, so too long probably?!)
    -Any hints for the easiest way to get this long recording?

  • in Bangle.js
    Avatar for Mi

    FYI: just checked here with kickstarter bangle2: HR is 10bpm(+-2) below chest belt in rest
    with Firmware 17.93 (already binary blob, right?) and current stable 18.00.
    With older firmware it was pretty exact at rest. So looks like this is a reproducible general effect.
    Glad you already have an idea about the cause.

  • in Bangle.js
    Avatar for Mi

    I guess you not think of GPS but double integration of acceleration.
    Be warned, that is very difficult - basically an ill posed problem for several reasons!

    Main thing is that every sensor is noisy. Integration amplifies this noise, so you will have wrong speed. This will change your location all the time without bounds, even if in reality you are standing still. So after double integration you will have very big error after very short amount of time.
    The only way you have a chance to get reasonable location from accelerometer is to make use of some other constraints.

    That could be the Magnetometer if you operate quite close to a strong magnet, but no way to count on earth magnetic field (lots of noise from all kind of metal and fields in the environment)

    Depending on what you want to do, you might think of instead make use of the gravity, since this is something that can anker you. But of course only if you can discriminate gravity and acc through some other constraints or system model (not magnetometer unfortunately).

    All this is not specific to bangle but true even for much more expensive sensors.

  • in Bangle.js
    Avatar for Mi

    For just HR the bangle recorder works just fine.

    which apps do you use for ECG analysis, Jukka Happonen's?

    Yes, I use this for recording ECG on the go.
    Locally I use a python app that gets all the data streams on a desktop computer, shows stores and analysis it there. The communication part looks pretty simple "just" initializing and receiving Bluetooth characteristics. The basis was from a blog post example. That link doesn't exist anymore though - just checked. There were a number of options at the time, so I think you should find several examples in the net somewhere.

    To me that looks all pretty basic BLE stuff (without being an expert) that I have seen similarly in bangle sw. So I guess it would be easy to write an bangle app for ECG and ACC, maybe even stop/start offline recording in the sensor.
    For ECG/ACC maybe just expanding BLE Heart Rate App a bit with additional characteristics.

    Is Polar's SDK open source?

    Yes there is a open SDK for Android. Its not complete though. All basic stuff is in there, including downloading the internal memory (H10 can record HR without device, not ECG though).

    Could EGC and the 2 Bluetooth devices support be implemented with open source?

    ECG yes.
    When I checked last I found no way to activate the 2 connection feature open source, but that may have changed (approx 2 years ago). As far as I understand it can be used open source once activated with proprietary app.

    Any source of documentation would be appreciated.

    Just google a bit. As said my original source is no longer online, but I could find a number of projects on github immediately, including swift or ROS.