noticed in dmesg:

[   24.625953] ath5k_pci 0000:02:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16                                                    
[   24.625966] ath5k_pci 0000:02:00.0: setting latency timer to 64                                                                   
[   24.626005] ath5k_pci 0000:02:00.0: registered as 'phy0'                                                                          
[   24.630376] ath5k phy0: Support for RF2425 is under development.                                                                  
[   24.700788] phy0: Selected rate control algorithm 'pid'          
[   24.843889] ath5k phy0: Atheros AR2425 chip found (MAC: 0xe2, PHY: 0x70)                                                          
[   24.869624] ath_hal: 0.9.18.0 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)                                            
[   24.882592] wlan: 0.9.4                                                                                                           
[   24.890582] ath_pci: 0.9.4
[  614.303734] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[  966.303846] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[  997.004026] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1018.301430] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1079.299800] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1141.299828] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1152.299895] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1163.004029] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1184.004033] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1195.004032] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1307.299800] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1318.300934] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1329.299819] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1410.303746] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1451.299862] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1492.299814] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1503.303787] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1534.302771] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1575.299775] ath5k phy0: noise floor calibration timeout (2447MHz)                                                                 
[ 1606.299734] ath5k phy0: noise floor calibration timeout (2447MHz)