Eric,
OK, the time period isn't a constant, but what is it measured in? Milliseconds? Then you can make milliseconds your discretization, and then resample the data at a coarser discretization with the coarse_grain() algorithm. Am I still not understanding your problem? Perhaps it would help if you were more explicit about what data is being pulled from the bus, exactly. Values and time? Time measured how?
Light finally goes on! I agree that this is a solution. To do this I use a sparse_series, and each point becomes a run, I believe. (Just for the record, pulling time and values.) Thanks for your patient explanation - I think it was the name "sparse" that was giving me problems, as I was thinking of it as dense with variable discretisation (40-60ms) rather than sparse at constant millisecond discretisation.
I'll have to get back to you about the rest. I'm leaving tomorrow for a long weekend.
Have a good weekend. Hugo