Hi Jared,
What you obtain is a modulated OQSPK signal. I assume you are looking for a filtered waveform that gives you a ring-shaped constellation.
If this is the case, then because oqpskmod and comm.OQPSKModulator internally upsample the signal (see doc note) as of R2016b, then it's better if you instead jointly filter and modulate the signal on your own:
a. Split bits to odd (I) and even (Q)
b. Filter both I & Q streams, e.g., with raised-cosine or half-sine filtering
c. Delay the even-bit stream (Q) by half a simple and make a complex waveform I + j*Q
Tasos
