With reference to
http://wiki.mikrotik.com/wiki/Manual:Interface/Wireless

noise-floor-threshold (default | integer [-128..127]; Default: default)

This property is only effective for cards based on AR5211 chipset

Which Mikrotik product uses this chipset and does this apply to other radio cards which use higher version of this chipset for example XR5 which uses AR5414.

This setting is working for that only legacy wireless card based on 5211 chipset and for newer N wireless chipset cards.

This setting is working for that only legacy wireless card based on 5211 chipset and for newer N wireless chipset cards.

Thanks for your reply - so N wireless cards should be ok