The Wi-Spy is not capable of reading the packets, so it will show all radio activity.    This is usually beneficial to users because they want to see other sources of RF activity in order to avoid them. 

I can see how a filter would be helpful, like tracking the signal strength, and knowing which activity you're creating.  However after a few moments of site surveying with a Wi-Spy you can get a good idea of your AP's activity. 

thanks for quick response ...but as I saw mac address coming up - I thought there might be a way to filter that way. And there is a big need to see whats happening in the RF space.

Yes, my interest is the RF energy level received from specific remote wifi clients (very remote and directional steerable) without the saturated energy from my local AP communicating to that client. Will play around with Wi-Sky. My issue is not interference from other RF sources:-)

I guess I am going to have to go up the layers...

Our software uses the wireless card of the computer to get mac-address information.

If you want protocol analysis, you could use a network sniffer such as wireshark. Using your windows driver to your wifi nic it will show only those packets that your nic would see (eg. to, from broadcast).

If you want a nice interface to all wifi devices, have a look at using the AirPCap adapter and WiFi Pilot. This is not cheap, but I think it would do what you want.

Note: I find having a suite of tools gives me the best results.

Insider
A quick look to see what APs are in range and signal strength.

WiSpy 2.x/dbx and chanalyzer
See what non-wifi radios and interference is on the spectrum. This is needed to see what could be causing any issues you have.

WireShark
A general packet sniffer.

AirPCap
A promiscuous wifi adaptor to see ALL wifi data in the air.
Note: this does not show any non-wifi signals! You need WiSpy for that.
This adaptor works with Wireshark, Cain, and CACE Techs Programs (WiFi Pilot and its bigger brother CACE Pilot). They also provide the api if you want to write your own softare.

WiFi Pilot
Good for showing lots of data about the wifi networks the AirPCap can see. It shows the things like the retransmissions, APs and clients etc.

Each product does things that the others don’t, so the collection working together is a good set of tools.

You can check out wifi pilot at : http://www.cacetech.com/products/wifi_pilot.html
They have some video clips, one shows how using AirPCap, Wifi Pilot, WiSpy and Chanalyzer all work together to identify an interfering device.

excellent....thank you