Unstable Wireless/Fluctuating SNR

Hello, I'm trying to get a good connection from my Linksys WRT150N in my basement. I recently purchased a Macbook Air with an internal wireless N airport card.

I'm getting frustrated because my connection seems to be right at the edge of my router's range. I flashed the firmware on the router and installed dd-wrt so that I could increase the Tx setting on the antenna. I've tried a couple different settings with only small (or perhaps no) improvement. One thing I noticed however is that my SNR (Signal to Noise Ratio) is jumping all over the place for the Mac. It will be at an SNR of 50 one second and 2 the next. I'm pretty new to this more advanced networking so I'm not exactly sure why my connection is jumping around so much. My noise seems pretty steady at -80 while my signal will pinball all over the place.

Is there anything I can do to improve/stablize my signal strength? Can I tweak the airport receiver somehow, or is there something more I can do to the router? Will I just have to bow to the inevitable and move my router?

Any help would be very much appreciated.

 

sounds more like interference than attenuation--and beleive it or not moving your router by a small distance can make a difference

It might be sitting right below a flourescent light and the ballast in those things can cause interference

 

Thanks for the response. My router's not really all that movable at the moment because doing so would require some re-wiring of the hardwired components in my network (I literally have no slack on a couple of cat 5 cables).
I've temporarily given up on the plan because I've bodged together a temporary solution by pressing an old wireless G router I had lying around and a 7db antenna into service much closer to my wireless devices. While I'd like to be able to use WPA2 it isn't the end of the world and I'm getting decent download speeds with this set up.

 

ah, well, necessity is the mother of invention.