No air integration in high-end and tech DCs . Why ?

[fnog]

GrumpyOldGuy,

I think you misunderstood the proposal: having a digital transmitter and piezo included in an otherwise classical analog SPG hausing means that:
- you do not have to touch the computer any more when switching, as the gas switch is automatically visible by the DC and registered
- failure of the digital pressure gauge or xmit module does not affect the analog SPG (one device being electronic and the other mechanical by nature, they will not interfere with eachother)

Planning is justified during trainings, I suppose (never done tec dives), and the need for planning will not just vanish because some extra data is available on the DC & logs. Or am I overlooking something ?

--

For those who fear that passive radio com can reach only a few inches distance, and that it works only in the total absence of RF noise or any other devices, I invite them to brush up on radio fundamentals, and wonder: do you get connected to your neighbours wifi by accident because they live too close ? Are you unable to use yours when they switch theirs on ? Do you log your collegue out when you present your card to the office reader ? A number of toy electronics kit offer to build crude AM radios that are powered only by the antenna and they can catch stations that are 100s of miles away.

 

[guyharrisonphoto]

I can't offer any reason, other than to say that I've always though that AI was a great solution to a problem that didn't exist. An SPG is a remarkably simple, accurate and pretty-much fool-proof way of monitoring gas supply. In tech diving, some combination of experience and training mean that most divers already "know" (in that the consumption has been calculated in advance) what their tank pressure will be and checking the SPG is something of a formality and confirmation.

I've never used an air-integrated computer, and none of my buddies use them, so this is probably a stupid question, but if someone is using an AI computer, do they eliminate the SPG altogether? If not, then the AI is really just "fluff". If they do, then that strikes me as relying on a bit of wireless technology for some pretty critical information.

Hi Stoo,

I use AI and an spg clipped off to my waist D-ring. The AI is very convenient in having all critical information on your wrist. In the post-dive log it also gives valuable air consumption information under different conditions (currents, deep, high effort, low effort, etc). So, I use it. Is it "fluff"? Maybe, but I find it very useful. My spg gives me bullet proof redundancy on gas supply.

If a transmitter fails, the computer still functions. So, if I look at the computer and it is not showing gas pressure, no big deal as I have spg back-up.

There is sometimes a mis-perception that if the AI fails it means the computer deco calculations fail. This is not the case, they are separate things. There is no "dead computer" or "dead you" if a transmitter fails or the signal is lost. It only means the gas pressure does not show on the screen.

 

[Lorenzoid]

[H]aving a digital transmitter and piezo included in an otherwise classical analog SPG hausing means that:
- you do not have to touch the computer any more when switching, as the gas switch is automatically visible by the DC and registered
- failure of the digital pressure gauge or xmit module does not affect the analog SPG (one device being electronic and the other mechanical by nature, they will not interfere with each other

I'm sure it's technically feasible if enough resources are devoted to the project, but the question is whether there is sufficient demand for this to justify the engineering/testing and manufacturing cost? You are suggesting modifying an analog gauge of a design that has existed and worked well in all kinds of harsh environments--not just diving--for decades by adding a digital transmitter to it. The so-called brass-and-glass SPG is a marvel of simplicity, robustness and economy.

---------- Post added June 4th, 2014 at 11:45 AM ----------

. . .
There is sometimes a mis-perception that if the AI fails it means the computer deco calculations fail. This is not the case, they are separate things. There is no "dead computer" or "dead you" if a transmitter fails or the signal is lost. It only means the gas pressure does not show on the screen.

Ideally, yes. But the ability for the computer to continue to function without the AI input is something that has to be engineered into it. This is a feature, and like any feature of any system, it is at least theoretically subject to failure. If poorly engineered, it is not impossible for a failure of the AI input to affect some other aspect of the computer. The only way to guarantee that a failure of one system will not affect the other is to separate the systems.

 

[markmantei]

There are plenty of "high-end" computers that provide for air integration. Suunto has the D9tx, DX, and Helo2 computers. Uwatec has already been mentioned. Hollis has the TX1. Liquivision has the Lynx. The only thing I see in common between all of these computers is that I don't know of a single technical diver that uses them with wireless integration, on technical dives. Shearwater seems to me to be the odd man out as far as lacking technical wireless integration, but maybe they just read the market better than everyone else.

Speaking for myself, yes I will use AI on a single tank rec dive in the carribean, with an anaolg SPG as a backup. No I won't use it on a technical cold water or cave dive. For me, it isn't even a matter of reliability, we carry back-up gear to guard against failure, and an analog spg can fail too. The issue is that transmitters are just to bulky, and have been shown to be unnecessary. Plus, diving sidemount I am routinely switching tanks. Doing gas switches on deco is pretty straightforward, you are often killing time anyway, and the 15 or 20 seconds to perform the gas-switch amounts to nothing. Doing gas switches on the working portion when switching SM tanks or when dropping/recovering stages will get old fast, when it is unnecessary as you are not switching mixes. I have better things to do and more important things to be watching than staring at my computer to do a gas-switch.

Overwhelmingly technical divers neither trust nor use wireless AI on technical dives. I think it is pretty clear from the number of technical divers using AI that it just isn't wanted/needed by the vast majority of the market.

 

[TSandM]

You have to realize that the technical or cave diver's approach to a dive is quite different from the average recreational diver's approach. Rec divers get in the water and dive until their gas supply gets low, then shallow up or ascend and end the dive.

Technical divers sit down well before the dive -- sometimes days or even weeks before -- and PLAN the gas required for the dive. This means they have a very good handle on their typical gas consumption at various depths and under various workloads. They know the rough depth and time of the dive they intend to do, and they figure out how much gas it will take to do it, and then add a contingency factor to allow for various kinds of problems, like gas loss or being delayed and needed to do more in-water time than was originally planned. Those contingency amounts are always calculated so that there will be a liberal excess of gas.

So, if you get in the water with what you KNOW is enough gas, plus; and you do the dive you planned (which is part of the discipline of technical diving) then the SPG becomes just a DOUBLE-check on the accuracy of your planning, not a primarily driver of dive decision-making. You certainly wouldn't want to dive without one, but knowing your pressure on a continuous basis just isn't critical. For a tech diver, the $600 or so you'd spend on a transmitter translates into a couple of charter boat fees, or several tanks of high helium mixes, or a whole boatload of sob . . . money's better spent there, than on a fancy gadget that doesn't add much to your diving.

 

[muzikbiz22]

I use AI and an spg clipped off to my waist D-ring. The AI is very convenient in having all critical information on your wrist. In the post-dive log it also gives valuable air consumption information under different conditions (currents, deep, high effort, low effort, etc). So, I use it. Is it "fluff"? Maybe, but I find it very useful. My spg gives me bullet proof redundancy on gas supply.

If a transmitter fails, the computer still functions. So, if I look at the computer and it is not showing gas pressure, no big deal as I have spg back-up.

There is sometimes a mis-perception that if the AI fails it means the computer deco calculations fail. This is not the case, they are separate things. There is no "dead computer" or "dead you" if a transmitter fails or the signal is lost. It only means the gas pressure does not show on the screen.

What he said

 

[fnog]

TSandM,

I made no estimates, but I can not believe at this point that adding a pair of piezos and passive beacons to the trusted SPG will result in 600$ price increase.

On the matter of pricing and market, remember that the economics of electronic devices is all about reaching high volumes and integrating as many sensors and processing features as possible on the same chip. That indicates that sooner or later a common platform for both rec and tec should emerge. It could end up with either tec becoming a shrinking niche that uses only expensive devices that are not evolving (or tables exclusively), ... or into a common hardware platform + communication protocols that has all the necessary tec features (o2 concentration sensor calibration etc). It is my hope that not all wealthy rec divers value looks and bling over actual component quality.

Regarding planning and leaving the wetware's brain in control: as someone made an analogy with flying, I will pick it up. The idea is not to ditch the pilot and his flight plans. It is rather to keep the pilot, all his usual cockpit instruments with no distracting addition, but just add a totally non-intrusive flight recorder box in the back. Since the tec mode is a niche, the firmware would be more expensive, but at least the hardware would become cheaper and stay maintained.

Of course, the same hardware platform with a different firmware/modeswitch could be used in 'rec' mode, providing the same looks and "unplanned" profile as when using atomic or aeris latest stuff.

In the end my question seems to boil down to this:
- do tech divers have no use at all for air consumption data in their digital logbook ?
- is there any hardware requirement that would make it impossible to use the same platform for a tec and a rec DC ?

 

[tomfcrist]

In the end my question seems to boil down to this:
- do tech divers have no use at all for air consumption data in their digital logbook ?
- is there any hardware requirement that would make it impossible to use the same platform for a tec and a rec DC ?

Tech divers have no real use for it, because we "KNOW" how much gas we are using based upon the complexity of the dive....We've done it enough to understand the correlation between rate of work and rate of respiration.

The answer to the second answer is no. Tech divers regularly use rec computers as a backup, but put it in gauge mode.

 

[eelnoraa]

On this topic of reliability, I am no expert, but just under the impression that hardware developpers (especially those from Shearwater and the likes) could very well design a passive and reliable HP wireless gauge. One that works the same way as your office badge: no batteries needed as long as you are close enough to a powered receiver (the DC). If such a transmitter was included in the otherwise usual analog SPG (i.e. no extra housing/plumbing costs), the savings can be used for redundant piezo sensors and xmit electronics, to make 100% failure very unlikely.

There are a lot more going on inside a wireless transmitter than an office badge. Office badge is nothing more than a RF ID. In very simple term, it is narrow band antenna that resonance to the signal sent out from the door side. Then the door site pickup the resonance signal back from the badge. The badge has no any kind of intelligence. The door side is the one that doing too the authentication. In wireless AI, there is, first, a sensor that translate pressure to a voltage. Then there is an A-to-D converter to convert the analog voltage to digital. Then the transceiver transmitts the digitized tank pressure signal out. I don't see how all of these can be done passively

---------- Post added June 4th, 2014 at 10:43 AM ----------

....think you misunderstood the proposal: having a digital transmitter and piezo included in an otherwise classical analog SPG hausing means that:
- you do not have to touch the computer any more when switching, as the gas switch is automatically visible by the DC and registered
.....

How does your computer know you just go from one 2nd stage to another???

---------- Post added June 4th, 2014 at 10:54 AM ----------

For those who fear that passive radio com can reach only a few inches distance, and that it works only in the total absence of RF noise or any other devices, I invite them to brush up on radio fundamentals, and wonder: do you get connected to your neighbours wifi by accident because they live too close ? Are you unable to use yours when they switch theirs on ? Do you log your collegue out when you present your card to the office reader ? A number of toy electronics kit offer to build crude AM radios that are powered only by the antenna and they can catch stations that are 100s of miles away.

Passive radio can work a long distance as long as the active side is transmitting a lot of power. Your neighbor's wifi is NOT passive. In fact, for any passive item to work, there is got to be an active side. In your company badge example, the active side is the door side. In AM radio example, the station tower is transmitting a lot of power. As you can see the trend, it is always the receiving end that can be very low power or passive. The transiting end is the power hog.

As to RF fundamental, please also look up RF signal transmission efficiency in water.

---------- Post added June 4th, 2014 at 11:14 AM ----------

The question is what is AI bringing to the table. I don't think for tec diving, the cost of the transmitters (even per tank) and the DC is a real concern (considering the cost of He and other equipment they already have) if AI bring a true value. To me, consumption logging is not a good enough of reason. If you were to take a proper gas planning training by a good instructor, you will realize how easy it is to estimate and to keep track of your consumption rate after knowing a few piece of info, ie tank size/factor, average depth, dive time at that depth, ..etc. I hope a tec diver is aware of these information all the time in a dive. As for AI as a backup, I think backup needs to be simple and reliable. I think there are better backup method.

 

[Lorenzoid]

TSandM,

I made no estimates, but I can not believe at this point that adding a pair of piezos and passive beacons to the trusted SPG will result in 600$ price increase.

On the matter of pricing and market, remember that the economics of electronic devices is all about reaching high volumes and integrating as many sensors and processing features as possible on the same chip. That indicates that sooner or later a common platform for both rec and tec should emerge. It could end up with either tec becoming a shrinking niche that uses only expensive devices that are not evolving (or tables exclusively), ... or into a common hardware platform + communication protocols that has all the necessary tec features (o2 concentration sensor calibration etc). It is my hope that not all wealthy rec divers value looks and bling over actual component quality.

Regarding planning and leaving the wetware's brain in control: as someone made an analogy with flying, I will pick it up. The idea is not to ditch the pilot and his flight plans. It is rather to keep the pilot, all his usual cockpit instruments with no distracting addition, but just add a totally non-intrusive flight recorder box in the back. Since the tec mode is a niche, the firmware would be more expensive, but at least the hardware would become cheaper and stay maintained.

Of course, the same hardware platform with a different firmware/modeswitch could be used in 'rec' mode, providing the same looks and "unplanned" profile as when using atomic or aeris latest stuff.

In the end my question seems to boil down to this:
- do tech divers have no use at all for air consumption data in their digital logbook ?
- is there any hardware requirement that would make it impossible to use the same platform for a tec and a rec DC ?

At this point, you're just arguing that you see no reason why it can't be done, wouldn't substantially increase the price, wouldn't introduce failure points, etc. Others here with engineering knowledge have voiced their skepticism about one of more of these assertions. If you think you've got it all worked out, then why don't you design it? So far, none of the responses here suggest that there is a demand for it. If you want a high-end rec-tech kind of AI computer, several have been noted in this thread (e.g., Suunto D9tx, DX, and Helo2).