POOR
rssi_qual = rssi * POOR / 10;
rssi_qual = (rssi - 10) * (FAIR - POOR) / 5 + POOR;
tx_qual = (90 - tx_retries) * POOR / 15;
tx_qual = (75 - tx_retries) * (FAIR - POOR) / 5 + POOR;
beacon_qual = (60 - missed_beacons) * POOR / 10;
beacon_qual = (50 - missed_beacons) * (FAIR - POOR) /
10 + POOR;