Thanks for the info guys! They are both using antennas btw. I came in this morning and turned the RX gain up pretty high, roughly 45dB, and the constellation plot on the RX side is starting to look pretty square, which I think is a bad sign. My thoughts are that with the increase in gain, there is too much noise coming through.
I've been toying with adding in a frequency offset on the TX side. I've been adding and subtracting up to 30kHz from the center frequency and I haven't seen any improvement in the constellation plot on the RX side.
Another thing that is confusing me, on the TX constellation plot, before it gets sent to the USRP, there are 3 groupings, -.5, 0, .5. I'm not sure where the 0 points are coming from. Since this is DBPSK, there should only be -.5 and .5 groupings right?