I did not look at ndiswrapper sources but here is the information
regarding Signal Strength from NDIS drivers (if it is not right). If it is
correct sorry for redundant information....
I have found that NDIS_WLAN_BSSID (and NDIS_WLAN_BSSID_EX) structure holds
rssi field (signal strength in dBm) which is what is used to display
signal strength in Windows XP (supposely mandatory for NDIS 5.1 wireless
There is also a NDIS_WLAN_BSSID_LIST which holds variable number of
Unfortunately, there is only signal strength available. Noise power or SNR
is not seem to be available directly from NDIS layer.
Here is the same NDIS structure documented for Windows CE.
There is a piece of code fragment available via below link to get the RSSI:
There is also a reference from above link to a Wireless Research API (WRAPI)
The source code is available for download. It can be used as a reference
to access rssid field as well.