Adds filter for GPS senteces and faster reading form serial.

measurement_main.py

     ser.readline()
     try:
         while ser.is_open:
-            nmea_sentence = ser.readline()
-            write_to_file(output_file, "{}\n".format(nmea_sentence.decode("utf-8") ))
-            sleep(1)
+            nmea_sentence = ser.readline() #GPRMC
+            nmea_str = nmea_sentence.decode("utf-8")
+            if nmea_str.startswith("$GPGGA"):
+                write_to_file(output_file, nmea_str)
     except:
         if not ser.is_open:
             print_message("GPS serial port is closed. Exit monitoring thread.")
                 self.config["gps"],
                 baudrate=self.config["gps_baudrate"],
             )
-            gps_ser_filepath = "{}{}_gps_serial_monitor_output.txt".format(
+            gps_ser_filepath = "{}{}_gps.nmea".format(
                 self.config["folder"], self.config["prefix"]
             )
             gps_ser_thread = Thread(