I took a look at this paper. I was thinking about how to implement this in pysystemtrade. I decided to replace spot with price contract, near term future contract with price contract, and distant future contract with carry contract. I could certainly be wrong, so test for yourself, but when I did that the formula pretty much reduced to how Rob calculates carry.
If I recall correctly (haven’t looked in a bit) not much. I may not be thinking about it correctly, but I consider the carry signal as an “offset” to the trend signal, that is does carry give a headwind (how much do I have to overcome for the trend signal) or tailwind to trend.
Thanks, similar - shorts just don't work so well for any longer term strategy except in specific short periods of stress for particular markets (and in those spots we're glad to have them). I recently tested a few more strategies from AFTS. "Acceleration" and "Skew", similar experience there so much long attribution to performance. Skew has a good reason though, unless it's for trading Vol Indices which is very negatively skewed. You probably are thinking fine - it depends on how you built your system. Can be thought of the other way as well, using absolute carry also has trend signal in it unless you intentionally use techniques to get rid of it.