The VR3 is a bit of an exception as it is not a time constant computer, Thats why it has a time bar across the top so you can see the speed of time.
Having hacked some Suunto and Alladin computers eeproms I pretty confident that they do all the nescessary calcs in real time and dont use variable time
Certainly its programmably possible (and easier) to wite a constant time deco computer that can do mixes and show surface and NST times as confidendtly as it shows tissue saturation etc. Assuming you understand that the model is making the assumption that you will stay at that depth and on that mix or that you will accurately follow its surfacing profile and gas changes
For example. If you look at a Buhlman compartment and its been 1 second since you last examined it and you know its absorbtion paramentes (M values) and the current pressure, PO2 Phe etc, then you can calculate the increase in stauration of that compartment. Its pretty easy to also ask, well if it increases that much in this second, how many seconds till its saturated. Do this for each compartment and the shortest is the NST. OK this is a simple Bulhmann example but its just as valid for other models
The VR3 may not be perfect but I personally do find its NST and TTS display very usefull. As a large % of my dives are 40-50m I'm got in the habit of just swimming around until Dave and me just cant face the mounting TTS anymore
Having hacked some Suunto and Alladin computers eeproms I pretty confident that they do all the nescessary calcs in real time and dont use variable time
Certainly its programmably possible (and easier) to wite a constant time deco computer that can do mixes and show surface and NST times as confidendtly as it shows tissue saturation etc. Assuming you understand that the model is making the assumption that you will stay at that depth and on that mix or that you will accurately follow its surfacing profile and gas changes
For example. If you look at a Buhlman compartment and its been 1 second since you last examined it and you know its absorbtion paramentes (M values) and the current pressure, PO2 Phe etc, then you can calculate the increase in stauration of that compartment. Its pretty easy to also ask, well if it increases that much in this second, how many seconds till its saturated. Do this for each compartment and the shortest is the NST. OK this is a simple Bulhmann example but its just as valid for other models
The VR3 may not be perfect but I personally do find its NST and TTS display very usefull. As a large % of my dives are 40-50m I'm got in the habit of just swimming around until Dave and me just cant face the mounting TTS anymore
