Garmin Descent MK2

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ATJ

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It is been a while this I went into deco with my Mk1 but my recollection was the following:
  • The NDL counts down to zero and then gets replaced with TTS with no indication of what depth or how long your stop will be
  • It is only when you reach the stop depth that that it shows you the stop ceiling and a countdown of the stop time.
Perhaps I wasn't looking closely enough but I don't remember seeing anything between when I went into deco and I reached the stop depth that told me how long my deco stop would be. My Perdix shows this as did my Atom 3.0.

If I can dive my planned dive this Saturday, I'll leave the Mk1 on 21% and see if I can force it into deco and have a closer look. I'll be diving with 26% and will have the Perdix and VT 4.0 set to that. I may not get deep enough to go into deco but I'll see.
I finally got a change to test this on Sunday. I dived with 32% but set the Mk1 to Air (I had a Perdix and a VT 4.0 on 32% so I was safe).

So, yes, the NDL counts down to zero and then gets replaced with TTS. However, the temperature (top right) gets replaced with the ceiling (3m) and the bottom row (PO2 and Mix or Air in my case) gets replaced with the stop length. I watched the sop length slowly grow.

This is not in the manual at all and as the ceiling is top right and the stop length is bottom right with other fields in between, it is less than intuitive.

Interestingly, my buddy was diving on air and racked up 10 minutes of deco. He put is computer in range and looking at the display it was obvious what it was saying even I have no idea what brand of computer he was wearing or have I seen it before. If I'd shown him my computer there's no way he have know what it was saying.

The nice thing was I was able to easily switch back to 32% and I cleared the deco even before I reached my safety stop.
 

Gjoyce3

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Are the transmitters available to the public yet? I am seeing dates like February 2021 for availability everywhere I look.

FWIW, I picked up a Mk2i early and have been happy with it. I have about 10 dives on it. You do need to turn off "turn-by-turn" directions - finding this out floating 1/4 miles offshore was frustrating: "take a left on Velacitos" does not cut it. But I am impressed with the battery life and visibility of the screen along with the clarity of information presented for rec diving. The double tap is working just fine, although it will switch screens on its own, but not too often.
 

DoubleAA

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I have a MK2 and transmitter. Only a few dives on it but great so far. Transmitter has been flawless except for shipping with an almost dead battery.

It’ll even play a song to identify the transmitter.

 

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ross9

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I have a MK2 and transmitter. Only a few dives on it but great so far. Transmitter has been flawless except for shipping with an almost dead battery.

It’ll even play a song to identify the transmitter.


Do you find the beep of the sonar annoying while underwater? I saw a video the other day where the guy was complaining about the sound of the sonar beeping every 1 second, with the transmitter right next to his ear.
 

stuartv

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I have a MK2 and transmitter. Only a few dives on it but great so far. Transmitter has been flawless except for shipping with an almost dead battery.

It’ll even play a song to identify the transmitter.

:rofl3: What a gimmick!

But, it does reveal an interesting point. The tank pod is not a transmitter. It's a transceiver.

Other than receiving and responding to a command to "Identify", I wonder what other commands it will receive and respond to.

And I wonder what opportunity there is for mischief or just problems from that. Can I connect to my buddy's tank pod and do something to "mess with" his tank pod?

I think I had seen before where the Garmin literature implied that the tank pod itself did the SAC and maybe even GTR calculations. I dismissed it at the time, but now it seems like maybe that really is what they meant.

Do you use your computer to tell the pod what size tank it is attached to? So then it can actually calculate your RMV? And anyone that is monitoring that pod can see the RMV and GTR of that diver?

Does that mean I could connect to my buddy's pod and set it to the wrong tank size, so when he gets in the water, his computer tells him that he is using his gas much more quickly (or slowly) than he really is?

I use the PPS transmitters. I have never been concerned with security of my transmitters because they only transmit. Nobody can "hack" one.

But, a transceiver is a different matter. If it receives commands, then what commands are there? How does it know that it is receiving a command from the actual owner/user of the pod? How does it know the command is not from somebody being malicious? Or a buddy that just thinks he's being funny? Or just someone else nearby who has connected to the wrong transmitter by mistake?
 

guyharrisonphoto

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I certainly don't want to dive around your compadres if this is what you fear most. :wink: The "song" is to verify that the computer is paired with the intended transmitter so as to avoid any mistakes. But, it can't 'program' the transmitter to do anything but transmit pressure, as far as I know. Where did you see that the transmitter is actually performing computations? Would be interesting to know if that is the case.

EDIT I pulled up the manual on the transmitter. It appears that the watch does all of the calculations based on pressure transmitted from the transmitter. But, there is some two-way communication, in that the watch can be used to (1) Pair with the transmitter (usually only done once so the transmitter only "sings" once) (2) instruct the transmitter to emit a "song" to verify pairing, if for some reason you suspect it is not paired or if there are a lot of watches or transmitters in use and you want confirm that the transmitter on your tank is the one paired to your computer, and (3) adjust the power at which the transmitter emits.

It looks like all of the info regarding tank volume and starting pressure for the SAC/RMV calculations are entered into the watch and the watch does the calculations based on pressure received from the transmitter.

Can it be "hacked" to manipulate the pressure reading of a hated rival diver? Who knows? Maybe QAnon knows!
 

lairdb

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I haven't seen a direct link yet to James Blackman's fairly thorough review.


tl;dw: excellent overall, hard to outgrow, a few annoyances, Teric-killer.

I recently picked up a Perdix AI that hasn't gotten wet yet -- if I had the gorilla arms that appear necessary to wear it as a daily watch, I'd probably flip my Perdix and get one. Since I have stick-figure arms, nope.
 

stuartv

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I certainly don't want to dive around your compadres if this is what you fear most. :wink: The "song" is to verify that the computer is paired with the intended transmitter so as to avoid any mistakes. But, it can't 'program' the transmitter to do anything but transmit pressure, as far as I know. Where did you see that the transmitter is actually performing computations? Would be interesting to know if that is the case.

EDIT I pulled up the manual on the transmitter. It appears that the watch does all of the calculations based on pressure transmitted from the transmitter. But, there is some two-way communication, in that the watch can be used to (1) Pair with the transmitter (usually only done once so the transmitter only "sings" once) (2) instruct the transmitter to emit a "song" to verify pairing, if for some reason you suspect it is not paired or if there are a lot of watches or transmitters in use and you want confirm that the transmitter on your tank is the one paired to your computer, and (3) adjust the power at which the transmitter emits.

It looks like all of the info regarding tank volume and starting pressure for the SAC/RMV calculations are entered into the watch and the watch does the calculations based on pressure received from the transmitter.

Can it be "hacked" to manipulate the pressure reading of a hated rival diver? Who knows? Maybe QAnon knows!

Rest easy. It is far, FAR down my list of things I fear. :)

I can't remember exactly where it was or what I read previously that implied that the pod is a transceiver and that it did some of the calculations related to GTR in the pod. I do remember that what it said did not state explicitly that the pod did those calculations. It merely seemed to imply it. At least I got the part right about the pod being a transceiver and not just a transmitter...

I like the idea that the level of transmission power can be user-adjusted. That is pretty cool.

But, after using PPS transmitters for almost 6 years now, I can't say that I have ever had any kind of issue where this "Identify" feature on the Garmin would have helped me.
 
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