Why does my wireless signal look like this?

[far_ken_beauty]

Using inSSIDer on my windows computer I noticed my signal looked like this. See attached. Up and down like a yo yo.

I have an atheros card (TP-Link TL-WN651G) It is capable of 108Mb but I don't expect that….54Mb should be more than achievable?

pfsense 2.0 Beta 1

I also noticed my laptop isn't connecting at its capable 54Mb when there is full signal strength max I get is 36Mb then it drops down to 18Mb.

Could this be a freeBSD driver issue for this card?