raymondw

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• GPS recording at interval +1s

  @raymondw started

  • 13 comments
  • 2,061 views

  @Gordon replied
• GPS recording at interval +1s

  in Bangle.js • 3 years, 5 months

  

  Fixed it :)
  Don't know really what was set where, so I used a reset command I found in a threat AND I used the reset command I use for my own custom Ublox device.
  After another car ride (same ride as above to pickup the van) it looks nice!
  No more jitters and speed jumps!

  To be completely sure I "need" another session windsurfing, but the wind prediction is quite bad.
  So I probably continue working on my custom code and test somewhere in the next week.

  Below is the code I used via the web ide to reset the Ublox.

  function log_debug(o) {
    let timestamp = new Date().getTime();
    console.log(timestamp + " : " + o);
  }
  
  function writeGPScmd(cmd) {
    var d = [0xB5,0x62]; // sync chars
    d = d.concat(cmd);
    var a=0,b=0;
    for (var i=2;i<d.length;i++) {
      a += d[i];
      b += a;
    }
    d.push(a&255,b&255);
    Serial1.write(d);
  }
  
  function UBX_CFG_RESET() {
    log_debug("UBX_CFG_RESET()");
    writeGPScmd([0x06,0x09,
                 0x0D,0x00,
                 0xFF,0xFF,0x00,0x00,
                 0x00,0x00,0x00,0x00,
                 0xFF,0xFF,0x00,0x00,
                 0x07]);
  }
  
  function UBX_CFG_RESET2() {
    log_debug("UBX_CFG_RESET2()");
    writeGPScmd([0x06, 0x09,   // class id
                 0x0D, 0x00,
                 0xFF, 0xFB, 0x00, 0x00,  // clear mask
                 0x00, 0x00, 0x00, 0x00,  // save mask
                 0xFF, 0xFF, 0x00, 0x00,  // load mask
                 0x17]);
  }
  
  function setupGPS() {
    Bangle.setGPSPower(1);
    UBX_CFG_RESET();
    //wait(100);
    UBX_CFG_RESET2();
    setTimeout('console.log("Hello World");', 1000);
    setTimeout('Bangle.setGPSPower(0);', 1000);
  }
  
  setupGPS();
  

• GPS recording at interval +1s

  in Bangle.js • 3 years, 5 months

  

  Alright, not something I was hoping for, but there is a difference between the 2 units.

  I played with the first one due to the GPS 1s not being 1s. (name with B)
  The other one (name with C) was standard.
  This morning I had to take the car for maintenance and logged a car track.
  B has the jitters and jumps in speed.
  Model C has very nice curves and no big jumps (car and rain, there where some expected spikes)

  @Gordon Are there specific settings when the units are programmed?
  Or can I just throw a reset to default at the Ublox chip?

• GPS recording at interval +1s

  in Bangle.js • 3 years, 5 months

  

  I did another windsurf session yesterday and it shows the same.
  Big dips and huge peaks.
  Not related to swell, super flat behind the sand bars.
  On the second watch I used the NMEA speed value and it is spot on compared to my own build units.
  (custom code I wrote to see 1s, 2s and 10s average speed)
  The software we use to analyze our session only likes coordinates, recording speed is not a thing we would use.

  Looked at the code with NMEA and it does indeed use doubles.
  Need to think about this, maybe it is something silly with the output from the Ublox in this watch.
  I'll put the recorder on the other watch also to check if it is a specific watch issue or setting.

• GPS recording at interval +1s

  in Bangle.js • 3 years, 5 months

  

  Hi Gordon,
  I've designed and programmed my personal GPS devices based on M8N and M9N.
  Data from a Ublox chip normally is very accurate, but I use the binary protocol and not NMEA.

  Attached are 2 files, 1 is data from the Bangle, the other is from my own logger at 5hz.
  I've highlighted the suspicious part in the Bangle screenshot.

  When I look at the track points

    <trkpt lat="52.477275" lon="5.065324">
      <ele>-5.9</ele>
      <time>2021-06-22T14:50:57.000Z</time>
    </trkpt>
  
    <trkpt lat="52.477113" lon="5.065425">
      <ele>-12.3</ele>
      <time>2021-06-22T14:50:58.000Z</time>
    </trkpt>
  

  There is 19m between them, 19m/s = 68,4km/h

  For my personal devices I use double for lat/lon data, it almost looks like the current grid is not dense enough.

  I used km/h NMEA data from the Ublox on another Bangle and it is spot on! (other wrist)
  So I really suspect the lat/lon data from the recorded file.

  The Ublox spec has 8 digits, the recorded file 6 (page 141)
  https://www.u-blox.com/en/docs/UBX-13003221

  Could it be the difference between 32 and 64 bit?

• GPS recording at interval +1s

  in Bangle.js • 3 years, 5 months

  

  Yesterday I tested during a perfect afternoon on the water and it runs great at 1hz/1sec!
  Not a second went wrong :)

  Unfortunately the data itself contains several strange spikes in speed.
  Need to check if this is due to the quality of the recorded data or something else.

• GPS recording at interval +1s

  in Bangle.js • 3 years, 6 months

  

  Yesterday I received my watches and so far I like them.

  Want to develop my own app and during the first testing I've noticed a strange behavior.
  When recording GPS data the watch always records time +1 sec.
  Created a custom repo to test some things and used GPS Setup and GPS Recorder
  GPS Setup has PMOO and 1s as parameters
  GPS Recording just has 1s

  When logging a file
  1s = 2s
  5s = 6s
  10s = 11s

  Anybody with a suggestion?