Dos command to find active wireless connection signal strength (assuming there is a wireless connection)
If going to use this in a batch file then %A becomes %%A
FOR /F "tokens=2 delims=: " %A IN ('netsh wlan show interfaces ^| FIND "Signal"') DO SET SIGNAL_STRENGTH=%A
ECHO %SIGNAL_STRENGTH%
The basic command here, to see the full netsh wlan report is
netsh wlan show interfaces