handle an incoming mavlink packet from the master vehicle. Relay it to the tracker
        if it is a GLOBAL_POSITION_INT

def mavlink_packet(self, m):
        '''handle an incoming mavlink packet from the master vehicle. Relay it to the tracker
        if it is a GLOBAL_POSITION_INT'''
        if m.get_type() in ['GLOBAL_POSITION_INT', 'SCALED_PRESSURE']:
            connection = self.find_connection()
            if not connection:
                return
            if m.get_srcSystem() != connection.target_system:
                connection.mav.send(m)