SPG with integrated transmitter. Am I the only one who would like that ?

[fnog]

Hi all SBers,

about 3 years ago I had the folly to wonder openly here why AI was so uncommon in tec computers... Since then, I have seen that topic pop up again on SB, with always the same broken record two-sided stereotypical arguments thrown about. Please, don't bother.

What I did not see pop up again, is some suggestion I made then, during the fray : how about "upgrading" the classic analog SPG with a passive transducer+radio, such as those chips used in truck tyres nowadays, so that there would be no more need for separate transmitters, with all their o-rings, 'fake-handle' lumps, discharged battery problems, etc ... The transmitter would respond realtime to the dive computer queries, not at a fixed sample rate, and would be passive like a beacon or harvesting the radio energy from the dive computer. The SPG design would probably have to change a little, such as epoxy housing instead of brass so as to not shield the radio, but let's imagine for a second it would not change at all except for the added ability to transmit. Almost as simple as the original, no extra rings or parts, no risk of massive leak, and qualified/tested the same way.

Would you like such a development ? How much extra on a 'classic' SPG would you pay for that ? I know I would be ready to pay about 50 bucks extra on top of a premium SPG for that. Would you accept ~ 30% faster discharge of your computer battery to accommodate for the passive transmitter inside the "upgraded" SPG ? Of course I imagine it should be sold by a reputable brand (Shearwater, OSTC, Liquivision, rebreather cabling companies, Huish, Johnson...) , or maybe even a consortium of those, because the radio must not be locked-in, it has to be compatible with as many brands as possible.

Just for clarity: I did not do a proper study of whether this is feasible or not, and I do not work in the dive gear industry.

 

[tbone1004]

the biggest problem with that is the current SPG's use a bourdon tube and trying to get that to convert to a digital signal would be all but impossible unless the HP line was split, one into a bourdon tube, the other into the transmitter. This would then make the SPG quite thick to accommodate both technologies as their isn't much room inside of an SPG to begin with.
Submersible Pressure Gauges (SPGs) and Instrument Consoles | Dive Gear Express®
see the video at the bottom of that page to see how little room there is inside.

I'm not an expert in this field, but I don't believe you can use passive radio signals in water due to range problems, so I believe it has to be powered. The other issue if it isn't powered is how power hungry they are going to be. For it to be accepted by the technical community, the computer has got to have at least 6-8 hours of run time and that would have to be while powering at least 4 transmitters. Too complicated I think for anyone to try to tackle. Powered would be better

I think we are about to see a fairly good sized leap forward with AI offerings at DEMA this year with Scubapros acquisition of Seabear who already has AI in development and is currently commercial on the Suex DPV's, Ratio is supposedly releasing something as well so that should be a fairly good sized increase in the market.

For technical diving part of the problem with your idea is the size. Workable for backgas, but impossible for sidemount due to sagging and difficult on stage/deco bottles due to size. Right now everyone is really using the 1.5" slimline gauges and making them what would amount to at least 3x as thick would be difficult to work with due to the weight.

I'd love to see it, I really would, but I'd be much happier with a transmitter a little bigger than a button gauge than one integrated with an analog SPG.

 

[Dhboner]

Here we go again :-(

 

[fnog]

the biggest problem with that is the current SPG's use a bourdon tube and trying to get that to convert to a digital signal would be all but impossible unless the HP line was split, one into a bourdon tube, the other into the transmitter. This would then make the SPG quite thick to accommodate both technologies as their isn't much room inside of an SPG to begin with.
see the video at the bottom of that page to see how little room there is inside.

Thanks for the instructional link. Since DGX does not allow fullscreen, here is the direct link:

I'm not an expert in this field, but I don't believe you can use passive radio signals in water due to range problems, so I believe it has to be powered. The other issue if it isn't powered is how power hungry they are going to be. For it to be accepted by the technical community, the computer has got to have at least 6-8 hours of run time and that would have to be while powering at least 4 transmitters. Too complicated I think for anyone to try to tackle. Powered would be better

I have a few doubts on this, that only a some numbers could clear up, and I am no specialist either. With a power consumption that is proportional to the sampling rate, and the radios that are used nowadays in IoT, the consumptions can be extremely low. And come to think of it, truck tyre pressure sensors are much further away than the distance between your hip and your neck. And truck loads can be anything from salty water tanks, to magnets, or reels of copper wires.
As far as adoption by tec is concerned, if i understood correctly ;=] it is not necessary. Maybe the ability to read 4 passive radios or more would still be nice, for example for rec divemasters to check their flock, but only a nicety. If this suggestion would work only for rec and reduced range backmount, I would not be too sad anyhow. This is still how the vast majority of SPG "users" dive. One could even imagine adding a "deluxe" feature to warn that the SPG is in the sand, for 100 bucks, comes with a free twilight themed unscratchable housing ;-)

I think we are about to see a fairly good sized leap forward with AI offerings at DEMA this year with Scubapros acquisition of Seabear who already has AI in development and is currently commercial on the Suex DPV's, Ratio is supposedly releasing something as well so that should be a fairly good sized increase in the market.

I hope as well, and yes, the H3 is nice. I am actually trying to get a discounted one for my wife these days, but I am not holding my breath for AI on the H3 this year or ever. I reckon they will put it only on the next gen.

For technical diving part of the problem with your idea is the size. Workable for backgas, but impossible for sidemount due to sagging and difficult on stage/deco bottles due to size. Right now everyone is really using the 1.5" slimline gauges and making them what would amount to at least 3x as thick would be difficult to work with due to the weight.

I'd love to see it, I really would, but I'd be much happier with a transmitter a little bigger than a button gauge than one integrated with an analog SPG.

So, this would be interesting only if the sensor is such a tiny chip that it is directly fitted on the bourdon tube, with possibly an external larger coil antenna printed or molded in the housing.

I guess you are right, the foreseable evolution of those transmitters is just smaller and less power-hungry.

 

[stuartv]

I agree with tbone that I think the power requirements would make it unfeasible to have that as a passive thing.

Besides, I think you are thinking of it the wrong way. Instead of asking, how much would you pay to add AI to your SPG, you should be asking, how much would you pay to add a physical SPG to your AI transmitter?

When you ask it that way, I think it seems a bit more clear that most people would not want it.

And, if it WERE feasible to have a passive tank pressure setup, I would think someone would already be offering one. A tank pressure dongle that is 1/4 (or less) the size of the current transmitters, because it has no battery inside, would be really nice. Tiny. No chance of flooding. It would a no-brainer, if it were technically achievable. At that point, why not integrate it directly into the 1st stage?

I have AI on my rec reg set partly because I don't want an extra hose. I have a button gauge on the reg so I can check pressure when I put the reg on the tank. It's not a high degree of precision - but that it is not needed at that point. I'm just making sure the tank hasn't leaked down or something. A later step will be to confirm my computer is getting a pressure reading - and that it is a reasonable match to the button gauge.

I put my AI transmitter on my tech reg set, too. That lets me see my pressure without unclipping/clipping my SPG. It lets me have recorded gas usage data (which I WANT to be recorded at the same sampling rate as my depth). And it ensures that I'll have a pressure reading, even if I have to shut down my left post.

So, your proposal would not meet any of the desires I have that result in my use of AI.

Regarding the H3, I think what you're going to see at DEMA IS going to be the next gen - with AI. I think if they were going to release a "current gen" H3 without AI, they would have already done so.

 

[fnog]

I had a quick look at the theory for propagation of radio in sea water. There is tremendous attenuation because the salty water is so conductive, unless very low frequencies are used to carry the signal. And a low frequency, of say 1kHz is no good to power a beacon. The beacon would need an antenna that is kilometers long. If you tried to fit that antenna in a SPG casing you'd end up with a too thin wire that would be resistive and brittle.

OTOH one meter of sea water is so conductive that it is only a fraction of an Ohm, so you could imagine to power the beacon by conducting the milliamps of current for it directly through seawater... and it would stop working in the quarry or clean lakes...

Oh well. There goes the passive transmitter idea. ((flush))

About the H3, you reckon that current-gen H3 owners will not get AI, that they will have to update to the nextgen SP unit if they want it, right ?

 

[tbone1004]

@stuartv keeps saying that, but the technology is already in the H3, so unless Scubapro plans on putting new chips inside of the computer which is expensive and idiotic because the Suex T1 is already out so it can talk with their scooters, it would be insane for them to actually go to a different technology inside the computer for WAI. They just need to build the transmitter that is compatible. Whether they do or not is up to them, but I would be surprised if we didn't see it at DEMA this year.

 

[stuartv]

About the H3, you reckon that current-gen H3 owners will not get AI, that they will have to update to the nextgen SP unit if they want it, right ?

That is my very strong suspicion.

But, that will be okay if ScubaPro makes a good offer to trade in (or have it refurbished or whatever) the old SeaBear H3 and replace it with a new one that is AI-capable.

It seems there must be so few of the H3 out in the field in actual use that I can't imagine it would really cost that much for SP to offer us early adopters a very attractive way to upgrade to their latest.

Hopefully, we'll find out soon!

 

[stuartv]

the technology is already in the H3

I am not convinced of that. The only evidence of that is posts here from the now-former U.S. importer. That is not PROOF, to me. SeaBear nor Sub Gravity never gave a straight answer on whether existing H3s would have to be sent in for any kind of update to let them work with the SeaBear AI whenever it got released. So, the possibility always existed that, even without the SP buy-out, it could turn out to be that existing H3s were not actually compatible with their AI, out of the box. We'll probably never know, either.

Kind of like the original Motorola Xoom tablet was sold with the specification that it was 4G LTE capable, but that ability was not "turned on" yet. When that capability was finally available, the Xooms that had already been sold had to be sent in to the factory and, for something like $50, they would "enable" the 4G LTE.

I have been asked not to share the details that I was told. But, I think I can say this without violating that trust: Bear in mind that ScubaPro already has and has had their own version of an AI transmitter, which is surely (I conjecture with some confidence) not compatible with whatever SeaBear was working on for AI.

 

[stuartv]

If the SeaBear H3 turns out to not be compatible with the AI for the ScubaPro H3, hopefully, ScubaPro will perceive a benefit to themselves in converting existing H3s to the ScubaPro version and incentive current owners accordingly.

It would give them an instant base of in-the-field ambassadors who could talk about how much they love their computers AND how much they appreciate ScubaPro for taking such good care of them.

That seems much better for them than a bunch of H3 owners that are disgruntled because they feel like they got the shaft from ScubaPro for not releasing AI that is compatible with the existing H3s, after they bought them partly on the basis that the factory said AI is coming and existing models would be compatible.