Error taking gps data and putting it into a string

Projects Programming
5

Yes, use dtostrf.

#include <baudot.h>
#include <RTTY.h>

#include <NMEAGPS.h>
NMEAGPS gps;  // Define the object that parses GPS characters into...
gps_fix fix;  //   ... the structure containing all those field values.

#define GPS_BAUD 9600 // GPS module baud rate. GP3906 defaults to 9600.

#define gpsPort Serial1

// Define the serial monitor port. On the Uno and Leonardo this is 'Serial'
//  on other boards this may be 'SerialUSB'
#define SerialMonitor Serial

void setup()
{
  RTTY.attach(12);
  SerialMonitor.begin(9600);
  gpsPort.begin(GPS_BAUD);
}

void loop()
{
  if (gps.available( gpsPort )) {
    fix = gps.read();
  
    char buffer[16];

    RTTY.tx("alt: ");
    buffer[0] = '\0'; // empty the string
    if (fix.valid.altitude)
      dtostrf( fix.altitude_ft(), 1, 2, buffer );
    RTTY.tx( buffer );
    RTTY.tx("    ");

    RTTY.tx("lat: ");
    buffer[0] = '\0'; // empty the string
    if (fix.valid.location)
      dtostrf( fix.latitude(), 1, 6, buffer );
    RTTY.tx( buffer );
    RTTY.tx("    ");

    RTTY.tx("long: ");
    buffer[0] = '\0'; // empty the string
    if (fix.valid.location)
      dtostrf( fix.longitude(), 1, 6, buffer );
    RTTY.tx( buffer );
    RTTY.tx("    ");

    printGPSInfo();
  }
}

void printGPSInfo()
{
  // print position, altitude, speed

  SerialMonitor.print( F("Location: ") );
  if (fix.valid.location) {
    SerialMonitor.print( fix.latitude(), 6 );
    SerialMonitor.print( ',' );
    SerialMonitor.print( fix.longitude(), 6 );
  }

  SerialMonitor.print( F(", Altitude: ") );
  if (fix.valid.altitude)
    SerialMonitor.print( fix.altitude() );

  SerialMonitor.println();
}

If you want to try that NeoGPS version of your sketch, you can get the NeoGPS library from the Arduino Library Manager, under the menu Sketch-> Include Library-> Manage Libraries.

Of course, we still don't know which RTTY library you are using. None of the libraries I can find will compile with your sketch. :-/