I'm working on a research project looking at Mode 3A/C replies and have noticed some pulse patterns that look very similar which I suspect are Mode 2 replies. They appear to differ by just one pulse.
I'd like to extend my decoder to decode these as well but I'm struggling to find out how Mode 2 pulses are encoded. I know that mode 3A/C is encoded using the Gilham code but that excludes the extra pulse that I am seeing.
Is there a publically available document which explains how Mode 2 pulses are encoded ? I've search high and low and haven't found one yet.