FAIR
rssi_qual = (rssi - 10) * (FAIR - POOR) / 5 + POOR;
rssi_qual = (rssi - 15) * (GOOD - FAIR) / 5 + FAIR;
tx_qual = (75 - tx_retries) * (FAIR - POOR) / 5 + POOR;
tx_qual = (70 - tx_retries) * (GOOD - FAIR) / 5 + FAIR;
beacon_qual = (50 - missed_beacons) * (FAIR - POOR) /
beacon_qual = (40 - missed_beacons) * (GOOD - FAIR) /
18 + FAIR;