weird unknown WiFi detection (Airodump-ng)

[near-lumia]

Hi guys,
I run a wireless sensor networks with Alfa AWUS036H, and I detect in addition to normal networks, some networks with unknown bssid, <lenght: 0>, PWR -1, -1 MB ... What the **** is this

wifi.jpg

[X0rCode]

hello,

this means that the essid is hidden of the network here you can read more about it http://www.thelinuxgeek.com/content/find-hidden-ssids

[near-lumia]

Hi
thank's for ur reply , yes indeed the SSID is hidden, but the difference between my case and the topic one is the PWR & the MB (-1 is very very strange)