Adds GPS serial interface support.

measurement_main.py

         return
 
 
+def monitor_gps(ser, output_file):
+    ser.flushInput()
+    ser.flushOutput()
+    # skip first maybe uncompleted line
+    ser.readline()
+    try:
+        while ser.is_open:
+            nmea_sentence = ser.readline()
+            write_to_file(output_file, nmea_sentence + "\n")
+            sleep(1)
+    except:
+        if not ser.is_open:
+            print_message("GPS serial port is closed. Exit monitoring thread.")
+        else:
+            print_message(
+                "Something went wrong while monitoring GPS serial interface. Exit monitoring thread."
+            )
+        return
+
+
 class Server:
     def __init__(self, config):
         self.config = config
             )
             ser_thread.start()
 
+        if self.config["gps"] is not None:
+            gps_ser = serial.Serial(
+                port=self.config["gps"],
+                baudrate=self.config["gps_baudrate"],
+            )
+            gps_ser.isOpen()
+            gps_ser_filepath = "{}{}_gps_serial_monitor_output.txt".format(
+                self.config["folder"], self.config["prefix"]
+            )
+            gps_ser_thread = Thread(
+                target=monitor_gps,
+                args=(
+                    gps_ser,
+                    gps_ser_filepath,
+                ),
+            )
+            gps_ser_thread.start()
+
         if self.config["bandwidth"]:
             self.bandwidth()
         elif self.config["drx"]:
         type=int,
         help="Serial device baudrate",
     )
+    parser.add_argument(
+        "--gps",
+        default=None,
+        help="GPS serial device e.g. /dev/serial/by-id/usb-u-blox_AG_-_www.u-blox.com_u-blox_5_-_GPS_Receiver-if00",
+    )
+    parser.add_argument(
+        "--gps_baudrate",
+        default=38400,
+        type=int,
+        help="GPS serial device baudrate",
+    )
 
     args = parser.parse_args()