We are thinking on buying the spectrum expert solution, but there is a good question. Can an AP 1131AG be settle as sensor?
No not at this time. Only Spectrum Expert cards are supported. A future software upgrade will allow certain APs to be supported such as the 1242 and 1252 families. The 1130(1) will be end of lifed soon and replaced with the new 802.11n MIMO enabled 1140 series. I'm not sure if it will be supported or not.