When the module is working, the first step is sending a command to set its positioning system as the BDS alone via software. In this design, the module uses the baud rate 9600HZ to work and the rate is adjustable. BDS positioning module connects and transfers data with the wireless communication module through the serial port. It will send data every 1S. The design uses Unicore communication protocols. In Unicore protocols, the input and output statements are called message. Each message string is consisted of ASCII characters. The format is shown in Figure 5. All the messages are started with '$' , immediately following the message name, then a variable number of arguments or data will appear. The name and data of the message are separated by the comma. And the last parameter is '*', which is followed by the optional checksum. The total length of each message is not more than 256 bytes.