Atomic Cobalt compass problems

[Supermanwoot]

If only he would turn his immense talents towards developing a wireless Cobalt...

fixt

props to Ron, running tech help on this forum has to be tough as nails... or ferrous metals

 

[lotusdent]

Hello, everyone. I am very new to scuba board and tell you that it is a great place to get some cool ideas and pick a good deal of a knowledge, therefore thanks to all.
So, I tried to find, and it is probably my fault that I couldn't so far, some ways to contact anyone, by email, from Atomic Aquatics so i could ask some questions and get an appropriate help. But I guess scuba board is the only place to inquire.
Few day ago, after a week of anticipation, sense it was on back order, I received my new Cobalt and now it is three dives old. My first impression was as high as it should've been expected from a well thought and nicely constructed a "toy" like that computer. On my first dive I noticed that hose was a little too short for me. Another words computer was situated too close to my face and it was inconvenient to read compass and other information from its screen. But I wasn't too worried, because the worst thing that may happen, if a longer attachment is not available, I'll end up paying extra for a special order. And the rest of the dive all I was doing is checking again and again Cobalt's fine performance. Inhaling and watching how brightly burning numbers were smoothly discounting diminishing amount of air supply. Checking compass and reading all information that could be access on its engaging display. By the end of the dive we, that is four other divers who dove with me at the same time, got around and we all began joined exploration of a new computer.
Screen was bright and sharp enough for anyone to see and read. So first question was if computer is really reading temperature of the water properly? Mine was shooing 42'F and four others displayed 37-39, depending on models. Next two dives it was approximately the same difference. Cobalt was showing a higher temperature then other machines. I assume it maybe not as important as same other information, but I though that I could mention it.
Compass, in my humble opinion, is not true 3D. Horizontal reading, in comparison with any other position of the unit, quite differs. If I held Cobalt, in compass mode, parallel to the ground and then slowly raise it up, numbers quickly proclaim some significant changes. Willingly enough, I tolerate that it is me who is doing something wrong…any thoughts on that? (It was calibrated outside, with a reference line and on a piece of glass)
And today, the 3ed dive, first what I noticed that lower right set of numbers (amount of gas left in a tank) don't get change for a very long time. FOUR slow inhalation, to be exact, according to the display, did not effect on the amount of left air supply. I tried again - same thing. Couple of second latter, numbers got change, jumping quickly to a lower volume. I was finishing the dive and being still under water purge some large quantity of air, constantly watching display. Same picture. Effect was taking quite some time latter. On the shore, after doffing and taking some rest, I've decided to check it again. Woke up computer and took reading of 860 psi left in the bottle. I pressed purge button on my regulator and, watching the screen, held it for 7 seconds. (1 Mississippi, 2 Miss…….. and so on) After release, it took full 4 seconds for a number to jump from 860 to 760. Then, sometime latter, they returned to 785. I closed tank, disconnected the unit, washed with a fresh water both connectors, reconnected them again, open the tank and ran through whole exercise again - same picture. Any thoughts on that?

Thank you to all for your time and happy diving.

p.s. by the way, i still think it is a great piece of equipment and recently purchased SS1 and like it very much.

 

[RonR]

Hello, everyone. I am very new to scuba board and tell you that it is a great place to get some cool ideas and pick a good deal of a knowledge, therefore thanks to all.
So, I tried to find, and it is probably my fault that I couldn't so far, some ways to contact anyone, by email, from Atomic Aquatics so i could ask some questions and get an appropriate help. But I guess scuba board is the only place to inquire.

Atomic's main customer service contact is via telephone- I'll try to answer your questions below as best I can.

On my first dive I noticed that hose was a little too short for me. Another words computer was situated too close to my face and it was inconvenient to read compass and other information from its screen.

I believe there is a plan to offer multiple lengths. We get about as many complaints that the hose is too long as too short. In any case, the QD fitting can be changed to any other HP hose quite easily.

So first question was if computer is really reading temperature of the water properly? Mine was shooing 42'F and four others displayed 37-39, depending on models. Next two dives it was approximately the same difference. Cobalt was showing a higher temperature then other machines. I assume it maybe not as important as same other information, but I though that I could mention it.

This is also a report that has come in frequently. The Cobalt temperature sensor is a part of the depth sensor, and it's located fairly deep inside the unit, so it may not respond as quickly as some other computers. But whenever we have checked the Cobalt sensors against good thermometers, they have been very accurate. Based on our experience, I'd trust the Cobalt.

Compass, in my humble opinion, is not true 3D. Horizontal reading, in comparison with any other position of the unit, quite differs. If I held Cobalt, in compass mode, parallel to the ground and then slowly raise it up, numbers quickly proclaim some significant changes. Willingly enough, I tolerate that it is me who is doing something wrong…any thoughts on that? (It was calibrated outside, with a reference line and on a piece of glass)

First, these compass chips are not highly accurate- within 5° or so is quite good for them. That's about as close as you could get with a conventional analog compass (at least one small enough for diving), and no one can swim a course that accurately, so in practical terms this is fine. As far as the 3D compensation, it really should work well- if you are rotating the Cobalt accurately, say inside a frame against a reference line, then you might see that there is a small variation as you pass from horizontal to inverted, but it should read with reasonable accuracy in any orientation. However, if you are gradually raising the compass towards vertical, the magnetic vector the compass sees will diminish rapidly. You are moving the Cobalt closer and closer to being parallel to the angle it is attempting to measure. Depending on your location, you might reach a point well before vertical where the direction you are pointing the Cobalt becomes so close to parallel to the flux lines that tiny variations in how you hold the compass become huge swings in direction- it's impossible to hold it accurately enough by hand to keep a consistent heading. The magnetic flux is not parallel to the earth's surface, but varies with location (it's inclined 69°23' where we are, you can visit http://www.ngdc.noaa.gov/geomagmodels/struts/calcIGRFWMM to calculate for your area). That's why the compass needs to be calibrated in your area, and can't be set at the factory. This would be true of any digital compass, and conventional analog compasses can't, of course, be tilted much at all. Additionally, the compensation put in by the accelerometer depends on measuring an angle- if that angle is moving (you are moving the compass) it will be less accurate. The compass response is dampened for relatively slow underwater motions, readings that come from rapid motions are discarded, so moving more quickly topside will make the compass less accurate.

The other big factor is calibration accuracy, and just a few degrees off from a true 180° rotation will make a still useable, but less accurate compass.

It's probably better to think of the 3D feature as allowing you to view the screen from any angle- held vertical, sideways, or upside-down. It's still going to be important that the long axis of the computer be roughly in the horizontal plane. The closer it gets to vertical (referenced to the flux lines), the more difficulty it has determining a heading.

And today, the 3ed dive, first what I noticed that lower right set of numbers (amount of gas left in a tank) don't get change for a very long time. FOUR slow inhalation, to be exact, according to the display, did not effect on the amount of left air supply. I tried again - same thing. Couple of second latter, numbers got change, jumping quickly to a lower volume. I was finishing the dive and being still under water purge some large quantity of air, constantly watching display. Same picture. Effect was taking quite some time latter. On the shore, after doffing and taking some rest, I've decided to check it again. Woke up computer and took reading of 860 psi left in the bottle. I pressed purge button on my regulator and, watching the screen, held it for 7 seconds. (1 Mississippi, 2 Miss…….. and so on) After release, it took full 4 seconds for a number to jump from 860 to 760. Then, sometime latter, they returned to 785. I closed tank, disconnected the unit, washed with a fresh water both connectors, reconnected them again, open the tank and ran through whole exercise again - same picture. Any thoughts on that?

Thank you to all for your time and happy diving.

p.s. by the way, i still think it is a great piece of equipment and recently purchased SS1 and like it very much.

There is a delay (buffer) built into the gas display, to smooth out minor variations and provide stable readings. Since gas pressure typically doesn't change too rapidly and the system is accurate to only about 10 psi, we had felt that providing a stable number to look at was preferable to a display with the last digit changing rapidly. The buffer could result in an up to 9 second delay in registering a sudden change in pressure during a dive, and as much as 15 seconds on the surface, when it samples pressure less frequently. That's not a problem in practical terms, but we have found that many divers are concerned with the delay. So when you install the first firmware update (which we hope to have available on the Atomic website soon), you will see this update interval change to two seconds. The display will change more frequently, and therefore respond more rapidly to pressure changes. It will also begin reading initial pressure on the surface much more rapidly after you turn on the air.

 

[lotusdent]

Thank you very much for your time and such a full answer.

 

[free_electron]

First, these compass chips are not highly accurate- within 5° or so is quite good for them. That's about as close as you could get with a conventional analog compass (at least one small enough for diving),

Time to look for a different sensor then... that is just lousy.

 

[RonR]

First, these compass chips are not highly accurate- within 5° or so is quite good for them. That's about as close as you could get with a conventional analog compass (at least one small enough for diving),

Time to look for a different sensor then... that is just lousy.

We're constantly looking to find better components. The compass chip in the Cobalt is commonly used in handheld devices such as small GPS units (it essentially what is in the iPhone, for instance). You can get compasses that are much more accurate, but they are also much more expensive (and most are much larger, being designed more for navigational/ aviation applications, and use more power). We didn't think that the boost in accuracy to 1° or better from 5° would be worth, say, another $150 at retail to most divers. 5° is about what a typical analog compass of the type used for diving can resolve, and it's pretty hard to swim more accurately. The digital compass/ accelerometer combo also works in all orientations, which an analog compass will not do.

I absolutely expect that much more accurate small chips will become available, and we will be looking at them as they appear.

 

[fdarden]

If only you could add underwater GPS to these units, I believe that would be worth another 150 at retail! (hehe!)

 

[Dr. Lecter]

I had an unusual problem with my electronic compass the first time I used it a couple months ago, after calibrating it per the instructions using the box and a granite countertop with no metal nearby/under it. When I used the compass, despite being nowhere near metal, it wouldn't point quite true in some directions (North read as Northwestish) and would simply not point to others at all (turning slowly in a circle produced bearings ranging from the low 130s through the high 170s, but no other bearings).

I was concerned the chip might be bad, but before contacting Atomic I tried recalibrating it once more, this time securing the unit into the box with two strips of painters tape. The first time I'd calibrated it there was probably some slight shifting of the unit during the ''turn upside down and hit the select button" step, and I wanted to see if eliminating that would fix the issue. After calibrating this way once, the compass worked great. A small roll of 1" blue masking tape now accompanies my Cobalt box for calibrating when traveling.

Hope this might help someone with an erratic compass despite having followed the instructions as best the crappy box jig provided will allow.

 

[RonR]

Hope this might help someone with an erratic compass despite having followed the instructions as best the crappy box jig provided will allow.

Sounds like you found the issue, shifting in the cardboard box is certainly a possibility. I carry a small plastic brochure holder (BP800C, less than $2 from Tap Plastics, Plastic Brochure Holders and Acrylic Literature Displays: TAP Plastics ) that I cut to access the keypad. I put a bit of foam in the sides, and it gives an easy and accurate rotation for calibration. It could be an idea for a case...

Ron

 

[x46145]

After 32 dives with no problems from my Cobalt, the compass went wacky on me this Sunday. For some reason it decided that no matter which direction I turned, I would alway get a heading of between 230 and 234. i figured it might have been an odd calibration problem but was concerned because the compass had worked great for 30+ dives and I had checked it's previous accuracy versus an analog compass and my friend's D9 with comperable results. Basically, nothing had changed except that the Cobalt had sat dormant for about a month while I was busy at work and couldn't get out for a dive.
First couple tries at recalibration failed miserably (I'd turn the cobalt 90 degrees in one direction and get a reading of a 15 degree turn in the opposite direction). After about 10 tries I got it so that it would change headings accurately, just 30-40 degrees off in the same direction with the exception that if I faced between south and west the Cobalt would add about 100 degrees to the bearing (220 would read as 320). After recalibrating on different surfaces around my house for about an hour I've found that for the most part, my cobalt will read about 15-20 degrees off EXCEPT between south and west, which seems to be a completely random error. Sometimes the Cobalt adds 90 or 100 degrees, other times it subtracts 60-80 or as much as 180. The margin of error is not replicatable on any surface in my house - seems to come out random for each calibration.

Any ideas?