Radio Initialisation
Based on our reference transcript, and the MAP27 documentation it was possible to figure out what the handshaking sequence of messages was between the radio and PC. Armed with this knowledge, code was written that performed the handshaking, and then started into general communicaton with the attached radio. The handshaking was an immediate success, but we ran into bother when we were trying to get the data, data acknowedgement sequence working, as we were falling out of sequence very soon into the program and then the link was being dropped by the radio. This turned out to be caused by inaccurate use of our serial port library as opposed to invalid messges being sent.
After some rearranging of code, this problem was rectified and data was being received from the radio. This meant the next step was to transmit valid GPS data from a mobile radio and see if could we decipher it and display it. This transmission had to be done in the amateur radio band of frequencies as we have a licensed amateur radio operator but not a licensed marine band operator which is what mountain rescue use (hopefully, a situation to be rectified by the time of the June trial).
Deciphering the incoming GPS data was a task that involved manipulating the binary data with the intent of making the correct divisions to capture radio ID, latitude, longitude and time, and then displaying this in a human readable format.
By the end of last week, this was working as required and a program was running that captured MAP27 messages and displayed them, correctly formatted, on the screen.