I hope everyone will forgive a recent subscriber and lurker stating an opinion, but I wonder if this is going down the wrong road. I promised Dirk I'd get involved a while back and never did - so here goes nothing.
(Quick Intro: rEvo CCR Trimix Diver + Sidemount Diver + General OC - Guy who started the recent thread on CCR Explorers) On Oct 13, 2014, at 07:49 AM, Willem Ferguson <[email protected]> wrote:
I think we have different understandings of the logic. Your understanding: if a po2 is supplied, this means CCR and the value of po2 by itself is sufficient to detect a CCR dive. Therefore the code can use po2 to test for CCR-type calculations. My understanding: For CCR dives NO po2 is supplied, only the o2 sensordata.
You're assuming that the cell data provided in a CCR log is: a) interpretable. b) present. For example: If you get a log from a Shearwater predator or petral (used on JJs, rEvos, etc) you'll find that the logged values are the millivolt readings from the cells. You can only turn these into ppO2 readings if you also have the cell calibration data (Also in the memory dump, but not in the CSV or XML exported by Shearwater Desktop). You have to use the ppO2 value calculated by the computer during the dive. I have no idea what an AP Inspiration logs, or a Hollis Optima, or a Sentinel, but it's quite possible that the method of calculating ppO2 is slightly different for each one. Or.... a computer (e.g. an OSTC2) which is used with a fixed setpoint won't log pseudo-cell data (I don't think), but it's still a CCR dive. I wonder if it should be down to the import process to worry about what ppO2 data is available and process that down to a single ppO2 sample, which is then what subsurface uses for it's calculations. This then keeps all the 2-cells, 3-cells, fixed set-point, or whatever else, logic out of the critical sections. To be clear, I'm not saying don't include separate cell data in the log, but just that deco calculations only need to worry about the result of processing them. Having that data around can be useful for seeing when a cell is getting old / needs replacing. BTW I'm happy to provide an example of the data given in a Shearwater log when I get home (CSV or XML) Paul
_______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
