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Mike, Thanks for your comprehensive reply to my remarks about your computer. (Now that George Irvine III has left the forum, alas some of the fire if not the flames, has gone out) As you correctly surmised, my comments refer to an earlier model (carrying the Beauchat logo) not the IIa. Your new model points up that most of this technology is all " work in progress". A couple of points: Disregarding "clunky", an unreasonable perjorative about anyone's child, does the case contain large scale integrated circuits at this stage or are there individually manufactured boards? My question has to do with reliability, although as you point out the units have been in production for some time - with what kind of failure rate? My guess is that it is probably not economic to make the transmitters with VLSIs i.e., few parts, because that would lock you into particular operating structures. You are right - I had not realized that it was the frequency or duration of tapping that switches on the unit. (The day after using it, I began to wonder if there was such a thing as finger bends). As the unit has user changeable batteries, how does this trade off with maintaining the integrity of the case - how often does it flood? What happens if it does? I agree that no one comes close to storing the amount of data yours does. You said "The units store detailed summary information for the past 300 dives, and 13.5 hours of profiles at one second samples. The sampling rate can be changed from 1 to 15 seconds by the user. " Is that actually 13.5x60x60 = 48,600 observations? I'm sure that the pushbuttons are easier to use than the rheostat. It sounds like you have a cool machine in the IIa. Many thanks Peter Heseltine P.S. Now that George Irvine III has left the forum, some of the fire if not all the flames, may have gone out. On Thu, 25 Apr 1996, Mike Cochran wrote: > Peter, I don't monitor the forum any more, too much irrational flaming. > Occasionally, someone will Email something that might be of interest > to me, such as your 24 April posting. No flaming from here. > > I'm confused by your comment "...work in progress...", we were the first > company to produce a hoseless unit, and we've been making and selling > them for well over three years now. > > Sorry that you think our Tank Unit is "clunky", compared to the air > cylinder, it seems insignificant. FYI, the size was determined by four > factors: > 1. We wanted a powerful microprocessor system that could mean a > higher battery consumption. > 2. We wanted to have a robust transmitted signal which required > a large antenna and good capacity batteries. > 3. We wanted common, low cost, user replaceable batteries and > settled on "AA". > 4. We don't believe in gels or oils to make a weak case sustain > deeper depths. We have a structurally very strong case that > is air filled and can literally be driven over with a truck > > The Tank Unit actually is turned on by applying Tank Pressure (something > one should do before commencing a dive <g>). The tapping method is for > when you are away from a tank and was chosen because there are no case > penetrations to leak. The tapping can actually be very light, but must > be sustained for several seconds. Many people think you have to hit it > hard, but not so. > > Gas switch wise, yeah, another transmitter would be great, but cost too > much. What is there, we feel, is a good compromise. There are NO units > (I'm aware of) that directly measure PPO2 and compute based on that > reading, except our LIFEGUARD PPO2 monitor. > > You apparently are not aware of the NEMESIS IIa Nitrox product that is > shipping (not vapor-ware). The "weird blue box" with a rheostat has been > replaced with a "weird black box" with push buttons that allow the user > to change a whole bunch of stuff in the field without a PC. (It comes > with the NEMESIS IIa Nitrox and is an option with the NEMESIS IIa.) > > The algorithm we use is a highly modified Haldanean. > > Oh, the IIa also has a third mix for pure O2 (or thereabouts) deco. > > Your guess is wrong about data/profile storage. The units store detailed > summary information for the past 300 dives, and 13.5 hours of profiles > at one second samples. The sampling rate can be changed from 1 to 15 > seconds by the user. There is a HUGE amount of profile data stored such > as depth, tank, temperature, warnings, etc. that makes for a really > great reconstruction of a dive. No one else even comes close. > > Oh, the IIa has a fantastic looking (he biasedly states) active back- > light display that will blow your socks off. (Assuming you dive with > your socks on.) > > The choice of where one puts the brains is a trade-off. We went the way > we did because we have more peripherals (HUD, DIVEMASTER, etc.) available > to intercept and use the data transmission. Also, the tank is a far more > stable platform on which have sensors. I dove with a competitors product > and became frustrated because the damn Ascent Rate alarm kept going off > when I raised my wrist to look at the display as I was slowly ascending. > > BTW, we've been producing hoseless units for some time now, and have never > had a Tank Unit lost because of it being torn loose. On the other hand, > divers have lost Wrist Units, and we have had two found on the bottom in > Cozumel from being dropped overboard. We've also had a few Wrist Units > stolen by folks who thought it was the whole computer, what a surprise! > Replacing a Wrist Unit is cheap and simple and can be done in the field > without losing deco information. > > Just thought you might like to know. > > Kind Regards > Mike Cochran > > > On Wed, 24 Apr 1996, Peter N.R. Heseltine wrote: > > > Re Cochran and their hoseless unit (and I know this will get me flamed) but > > here goes: > > > > I think that this unit is a work in progress and for my purposes is > > paradoxically both too much and too little. > > > > First the unit itself is clunky: the CPU and transmitter reside in a 4 x > > 6 x 2 box that mounts on the tank valve and clips (?) to a hose. I doubt > > by the size that there are many VLSI chips involved and it's probably a > > standard circuit board. The unit turns on by either immersion/pressure > > or tapping on an area of the box. You have to tap pretty hard and I > > think that this, while theoretically neat, will make for practical > > failures. Most computers don't like being banged on. Batteries are AA > > for the CPU and Ns for the wrist unit. > > > > The unit allows for a gas switch. I thought that you would have two > > transmitter units, one for each tank. But no, when you stop breathing > > the unit assumes you have begun to use the second mixture. This > > obviously saves the expense of an additional CPU/transmitter, but means > > that the SCR is assumed and not measured. The pO2 of either gas may be > > adjusted in increments of 0.1%. To do so requires (1) a laptop or (2) a > > weird blue box with a "probe" and a rheostat. The latter stated for > > "field" use is really clunky and I found very difficult to use. > > > > The unit has many user settings for, not only gas, but "J" factors. I > > believe that it uses the Buhlman algorithm, but this can be considerably > > modified. All user changes require the use of a computer interface, > > although it will default in the event these are not set. > > > > The download profile is considerably more elaborate than the Air-X, but > > my guess is that this is due to software not actual additional measured. > > For example the profile display will give you a pPO2 profile and various > > other statistics calculated on time/depth measurements. (By the way this > > would be a nice addition to Abyss. i.e, to be able to plot the curves of > > various gasses over time, superimposed on the dive profile, rather than > > clicking on each waypoint and having them display in a table only for > > that waypoint. It is easier to get a feel for it as a graphic, which > > after all is the main point of Abyss). > > > > What would I like to see change in the Cochran/Beuchat unit? > > Miniaturization of the transmitter/CPU. Not only more convenient, but > > probably more reliable. Cochran's choice to put all the brains in one > > unit is a little scary to me. If it fails (? ripped off by a rock or > > snag ?) you have a paper weight on your wrist. At least the Air-X > > defaults to a depth/time computer with no gas info. i.e., if the tank > > transmitter (about 1 x 1 inch) fails (Which is in fact what happened to > > mine ultimately - no sweat, I still had all my deco info and I knew I had > > enough gas to get home). > > > > The gas switch concept on the Cochran in OK (it assumes you are at rest > > during deco on the second gas, I guess), but it would be nice to actually > > have a read-out from the 2nd tank. > > > > All in all, we the consumers are the losers not to have two companies in > > competition for our business. Too often these issues are settled by the > > lawyers, rather than for the benefit of the customer. And so it goes. > > > > Peter Heseltine > > > > > > On Wed, 24 Apr 1996, Wixson, Steven M (Mike) wrote: > > > > > I wish I knew. I went to Florida this past weekend and on the way out > > > to the dive site I tried to check my tank pressure and couldn't get any > > > tank data. I tried several times to re-pair it to no avail (it didn't > > > even give me the "pair" message). This is a new unit, it has seen action > > > no more than 4 times so I wouldn't expect it to be the batteries. > > > > > > Let me also give a warm thanks to Cochran for screwing all of us Uwatec > > > owners. > > > > > > Mike > > > > > > >---------- > > > >From: Peter N.R. Heseltine[SMTP:heseltin@hs*.us*.ed*] > > > >Sent: Wednesday, April 24, 1996 2:58 PM > > > >To: Wixson, Steven M (Mike) > > > >Cc: Harold Gartner; Erik Stein; Chris Parrett; Dennis Pierce; > > > >techdiver@terra.net; Peter N.R. Heseltine > > > >Subject: RE: Demise of Uwatec USA > > > > > > > >Mike, > > > > > > > >What exactly happened to your transmitter? Mine just failed in the > > > >middle > > > >of a dive - cold water for me (44oF). The wrist unit of course remained > > > >functional. The whole thing had been working fine for two years. I > > > >assumed > > > >it was the battery, but they (Uwatec) said no. They kept it and said > > > >they > > > >would run tests, in the meantime they sent me a new replacement wrist > > > >and > > > >transmitter. > > > > > > > >This same transmitter is used in the Mares and I believe the Oceanic > > > >units - so it may be of value to all to know exactly why they failed. > > > > > > > >Peter Heseltine > > > > > > > > > > > > > -- > > Send mail for the `techdiver' mailing list to `techdiver@terra.net'. > > Send subscription/archive requests to `techdiver-request@terra.net'. > > >
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