Garmin Descent MK2

[Peter Bomberg]

What transmitters are you using?

I shoot underwater using Inon Z240 strobes and I have never noticed them to cause an interruption in my AI readings. I am just wondering if we are using the same type of transmitters, or if you have a different kind.

We have had this issue with the transmitter that came with the Oceanic Atom 2 (a bit old I know), the Aqualung i770r and another computer that uses the same transmitter (dive budy so not sure what it was, but I can find out) in terms of strobes Inon S-2000's, Inon D-200 + Sealife Sea Dragon Universal Flash. Ironically the Aqualung i770R looses the signal many times per dive while my ancient atom looses it maybe every 5th dive.

 

[stuartv]

We have had this issue with the transmitter that came with the Oceanic Atom 2 (a bit old I know), the Aqualung i770r and another computer that uses the same transmitter (dive budy so not sure what it was, but I can find out) in terms of strobes Inon S-2000's, Inon D-200 + Sealife Sea Dragon Universal Flash. Ironically the Aqualung i770R looses the signal many times per dive while my ancient atom looses it maybe every 5th dive.

But, it's just one transmitter that you've had issues with? And it's one that came with an Atom 2?

 

[Peter Bomberg]

But, it's just one transmitter that you've had issues with? And it's one that came with an Atom 2?

Actually mostly the one that came with the Aqualung i770R, but we swapped all 3 around and the Aqualung had issues with all 3 transmitters.

 

[tursiops]

Actually mostly the one that came with the Aqualung i770R, but we swapped all 3 around and the Aqualung had issues with all 3 transmitters.

Kind of reminds me of the old joke about how water makes you drunk. After all, scotch and water, rum and water, vodka and water, they all make you drunk, and the water is the only thing common to all three drinks....

 

[Peter Bomberg]

Kind of reminds me of the old joke about how water makes you drunk. After all, scotch and water, rum and water, vodka and water, they all make you drunk, and the water is the only thing common to all three drinks....

Yes for a while (actually most of a dive) we thought the issue was the i770, but then I took pictures over the shoulder of my dive buddy and her computer lost the link so we repeated and could reproduce every time when I used dual strobes.

 

[vjb.knife]

I would think that if they make a AI sensor it would work with the MK1, possibly with a software update. The MK1 already is setup to work with a variety of other sensors for other activities like running and biking. I use it with a heart rate sensor and it links to a smartphone. That is unless a totally different type of communication than Bluetooth, or Ant+ is required underwater.

 

[dmaziuk]

That is unless a totally different type of communication than Bluetooth, or Ant+ is required underwater.

Yes.

 

[vjb.knife]

Yes.

That is what I figured. I don't believe that I would ever spend the extra $$ on AI anyway.

 

[ATJ]

I agree it's a very minor issue and both my GF and I have ongoing issues with our transmitters as do many of the divers I know, they are trivial but when near strobes that fire they loose the link.

I read your post a couple of days ago and it's been bugging me. I cannot work out how firing strobes could have any impact.

As far as I am aware, there is no "link" as such. The transmitter just broadcasts the current pressure every 5 seconds (or so). The computer just listens for the broadcast you've told it to listen to (the serial number on the transmitter which codes the signal). The computer sends nothing and just listens and so there is no link that can be lost or broken.

The computer has a timeout and if it doesn't receive the broadcast within the timeout period it goes into a warning mode. There's a second timeout which is for error mode. I don't know the lengths of the timeouts but they are certainly longer than the normal broadcast interval so it should be fine to miss at least one broadcast.

The duration of a strobe is 1/1000s or less. Firing a strobe once couldn't possibly have an impact. I guess potentially if you could get your strobes to fire continuously it might have an impact but even then I doubt it.

Personally, I have been using AI for over 6 years for close to 1,000 dives. I always take my camera on dives and shoot 100-300 photographs per dive. I have two strobes. My dive computers are mounted on my camera rig, so relatively close to the strobes. I'm using Oceanic badged transmitters. I have never had a strobe firing cause any issues with AI.

I have a Shearwater Perdix AI and an Oceanic Atom 3.0. The Perdix almost never shows a problem with AI (perhaps once in 20-30 dives) and when it does it's to do with where the Perdix is in relation to the transmitter (distance or angle). The Atom is not as reliable (perhaps misses once per dive) but again it is to di with distance or angle. The Atom seems to become less reliable at the end of the dive when there is less gas in the tank and I suspect the pressure may impact signal strength.

 

[stuartv]

@ATJ I agree. I don't see how a strobe flashing could do more than make it miss one transmission. 5 seconds later, it should get the next transmission. Unlesss.... If the strobe somehow creates a disruption that has an effect that lasts longer than the actual strobe burn time. Say, maybe it's something about the EM radiation that is put out when the strobe is recharging after it fires. Then it could have an effect that lasts 2 seconds or more (depending on the strobe and at what power you fired it). If that is happening, then you wouldn't even have to get THAT unlucky to disrupt the AI signal multiple times in a row.

That said, I personally am more inclined to think that @Peter Bomberg has been unlucky enough to have a flaky Aqualung 770 AND a really old transmitter (that came with his Atom 2) and it's really those two specific devices that are having the issues.

Like you, I have been diving regularly with a camera with 2 x Inon Z240. I usually take 100 - 200 photos on each dive, and I have never noticed any interruption in my AI. Other than an occasional momentary dropout that seemed to correlate to having the computer at a bad angle/distance to receive the AI transmission.