called rapidly by mavproxy

def idle_task(self):
        '''called rapidly by mavproxy'''
        now = time.time()

        if now-self.last_sent > self.system_time_settings.interval:
            self.last_sent = now
            time_us = time.time() * 1000000
            if self.system_time_settings.verbose:
                print("ST: Sending system time: (%u/%u)" %
                      (time_us, self.uptime(),))
            self.master.mav.system_time_send(time_us,
                                             self.uptime())

        if (now-self.last_sent_timesync >
            self.system_time_settings.interval_timesync):
            self.last_sent_timesync = now
            time_ns = time.time() * 1000000000
            time_ns += 1234
            if self.system_time_settings.verbose:
                print("ST: Sending timesync request")
            self.master.mav.timesync_send(0, time_ns)
            self.last_sent_ts1 = time_ns