Broken Lat/Long conversion near absolute longitude lines and equator

[m1geo]

When referring to the code converting to Lat/Long for APRS transmission, there is a bug. The code only covers when dm_lon is less than 1000, but, should be extended to include <100 and <10:

https://github.com/lightaprs/LightAPRS-1.0/blob/82fba0337935b802f001e48789f66ba36653b793/LightAPRS-vehicle/LightAPRS-vehicle.ino#L282-L287

Otherwise, this causes cases similar to below, where you can see that the longitude has a space in it since the case where dm_lon is less than 100 (as 10.83 is) is not covered.

2021-01-21 16:56:30 GMT: M1GEO-9>APLIGA,WIDE1-1,WIDE2-1,qAR,MB7UM:=5210.94N/00 10.83E>037/000/A=000090 056TXP 791RXP 27.70C 985.01hPa 4.59V 12S [Invalid uncompressed location]

I added a the following to resolve the issue:

  if (dm_lon < 100) {
    lonStr[2] = '0';
  }
  if (dm_lon < 10) {
    lonStr[3] = '0';
  }

2021-01-21 18:57:27 GMT: M1GEO-9>APLIGA,WIDE1-1,WIDE2-1,qAR,MB7UM:=5210.99N/00010.83E>095/028/A=000067 013TXP 081RXP 23.80C 984.81hPa 4.57V 12S

There should probably be similar tweaks to the latitude, allowing for operation close to the equator - however, this is not an issue for me...

Cheers, George - M1GEO.

[dl9sau]

dtostrf() adds leading blanks if the number is smaller than the reserved field. This should be the nicer approach (diff):

@@ -439,6 +532,7 @@ void updatePosition() { // Convert and set latitude NMEA string Degree Minute Hundreths of minutes ddmm.hh[S,N]. char latStr[10]; int temp = 0;

• char *p;

  double d_lat = gps.location.lat(); double dm_lat = 0.0; @@ -452,11 +546,10 @@ void updatePosition() { }

  dtostrf(dm_lat, 7, 2, latStr);

• if (dm_lat < 1000) {

• latStr[0] = '0';

• }

• // smaller numbers lead to leading blanks. Replace by '0', for correct aprs positions

• for (p = latStr; p && p == ' '; p++)

• *p = '0';

• if (d_lat >= 0.0) { latStr[7] = 'N'; } else { @@ -480,13 +573,9 @@ void updatePosition() {

  dtostrf(dm_lon, 8, 2, lonStr);

• if (dm_lon < 10000) {

• lonStr[0] = '0';

• }

• if (dm_lon < 1000) {

• lonStr[1] = '0';

• }

• // smaller numbers lead to leading blanks. Replace by '0', for correct aprs positions

• for (p = lonStr; p && p == ' '; p++)

• *p = '0'; if (d_lon >= 0.0) { lonStr[8] = 'E'; } else {