Hello Andrew,
I have been doing the calculations manually. I am
working on DVB and they seem to use MER rather than
EVM. I am only interested in QPSK and 8PSK as the
other constellations are not supported by Spike.
In my own receiver software I use
https://en.wikipedia.org/wiki/Modulation_error_ratio
calculating the RMS error and signal vectors from the
samples. Example here http://g4guo.blogspot.co.uk/
I hope you are able to add it as it would help me.
– Charles