HopeToBeUseful1day

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

  @HopeToBeUseful1day started

  • 11 comments
  • 1,067 views

  @halemmerich replied
• I demand BangleJS3!

  in Bangle.js • 1 year, 5 months

  

  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 • 1 year, 5 months

  

  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 • 1 year, 5 months

  

  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 • 1 year, 5 months

  

  Dual-frequency GPS please

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

  in Bangle.js • 1 year, 5 months

  

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

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

  in Bangle.js • 1 year, 5 months

  

  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 • 1 year, 5 months

  

  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.