Wifi LAN card external control

Is there a way to control the wifi card available in laptops ? I mean can the transmission be some how controlled externally? (i am pursuing a project in spectrum sensing . I want to use laptop(s) as primary users and secondary users which can be controlled by fpga and sensing the spectrum by seperate built up rf front -end. i have not gone into the actual building of the system.)



thanks to anyone who gives insight. I am new to edaboard too (had an account; left it unused; now realising its importance) . but this is fun and pretty useful stuff.
Thanks administrators - wonderful website.

Do you mean use the wifi cards as sensors?

You can get "special" cards that are useful for wi-fi measurements (intended to figure out coverage blackspots). I'm sure they are not cheap.
You can also develop your own analyzer, using a TI/Chipcon device, essentially using the RSSI indication from these devices. See here.

If you mean can you use the wifi cards as conventional cards, but controlled from a different device (not laptop), then yes that is possible too if you can find a chipset that is popular. Some early 802.1b wifi cards have source code which you could glean from either Linux source code or elsewhere. I guess other wifi standards are possible too, but I've never looked.