Hi Ben,
We do need to compute phase using a arctan on board, and then unwrap it since sometimes the resonators we are reading out are of poor quality and just rotating them in the IQ plane doesn't solve our phase wrap problem. Sean's drew up the (simple in code, not quite as simple in simulink) algorithm yesterday so we'll test it today.
p756 of Lyons has an arctangent algorithm for hardware implementation http://www.amazon.com/Understanding-Digital-Signal-Processing-3rd/dp/0137027419/ref=ntt_at_ep_dpt_1 0.28-degrees maximum error. Looks like its reproduced from his other book (Chapter 15) http://www.amazon.com/Streamlining-Digital-Signal-Processing-Guidebook/dp/0470131578/ref=ntt_at_ep_dpt_2 which happens to be available for free download on IEEE Xplore; go to Browse->Books, and then search for the title. I'll send you the chapter. Cheers, Dave
