HopeToBeUseful1day

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• Did anyone manage to get SBAS reliable working on B2?

  @HopeToBeUseful1day started

  • 11 comments
  • 802 views

  @halemmerich replied
• I demand BangleJS3!

  in Bangle.js • 9 months, 1 week

  

  Does it mean nrf5340 would drain the battery when working with audio?

• Did anyone manage to get SBAS reliable working on B2?

  in Bangle.js • 9 months, 1 week

  

  Looks like @BillM implemented the checksum function another way. His version computes 28 without "$" sign. Attached screenshot

• Did anyone manage to get SBAS reliable working on B2?

  in Bangle.js • 9 months, 2 weeks

  

  I'm not sure if "$" should be accounted in the checksum.
  As shown here, NMEA checksum calculation does not include "$" and "*"

  Lets assume the following NMEA sentence:

  $GPGLL,5300.97914,N,00259.98174,E,125926­,A*28
  

  In this sentence the checksum is the character representation of the
  hexadecimal value 28. The string that the checksum is calculated over
  is

  GPGLL,5300.97914,N,00259.98174,E,125926,­A
  

  To calculate the checksum you parse all characters between $ and *
  from the NMEA sentence into a new string.

• I demand BangleJS3!

  in Bangle.js • 9 months, 2 weeks

  

  Dual-frequency GPS please

• Did anyone manage to get SBAS reliable working on B2?

  in Bangle.js • 9 months, 2 weeks

  

  I thing line 19 of the presented code add the leading "$"

• Did anyone manage to get SBAS reliable working on B2?

  in Bangle.js • 9 months, 2 weeks

  

  Thank for the reply. The post misses the checksum. The real code is:

  function checksum(str) {
  	var cs = 0;
    
  	for (const c of str) {
  		cs = cs ^ c.charCodeAt(0); //XOR
  	}
    
  	return cs.toString(16).toUpperCase().padStart(2­, '0');
  }
  
  function configureSBAS() {
     const thisTime = new Date(); 
     let timeString = thisTime.toISOString();
  	
    // SBAS satellite (SBAS satellite No. 1-19, corresponding to PRN 120-138
    var cmd = "PCAS15,4,FFFF"; //turn on satellites 1-16 of SBAS
    //var cmd = "PCAS15,4,7FFFF"; //turn on satellites 1-19 of SBAS
  
    cmd = "$" + cmd + "*" + checksum(cmd);
    Serial1.println(cmd);
    writeLogFile(timeString + ": " + cmd + "\n");
    
    SBASon = true;
  }
  

• Did anyone manage to get SBAS reliable working on B2?

  in Bangle.js • 9 months, 2 weeks

  

  Playing with @BillM 's code. Despite forcing AT6558(R?) into the SBAS mode by sending

  "PCAS15,4,FFFF"
  

  to the chip, the error is still over 7 meters.
  Is there a way to get the error below 2 meters as stated in most SBAS articles?

  UPD:
  After taking weighted by time between records average of recorded coordinates at a static point and comparing those average coordinates to the true coordinates, the error seems to be closer to 20 meters.

  UPD2:
  The command checksum is not included in the post. When the command is sent to the GPS chip the checksum is added.