Recalibrating Cobalt’s Compass?

[Akimbo]

Any suggestions for recalibrating the Cobalt compass without carrying all that cardboard when traveling? Why can’t you just flip the thing over on a tabletop or held against an unreinforced block wall? It seems like the only objective is to rotate it face-up and face-down along the same centerline.

What exactly is going on with the internals using this procedure anyway? Not very intuitive to me.

 

[Dr. Lecter]

I use the Pelican case in which I carry it...but that requires making sure to cut the foam pretty carefully...and reaching underneath to mash the buttons is tricky. RonR has said he uses some foam and a plastic leaflet holder to accomplish the same thing.

 

[Atomic Aquatics]

Akimbo....I will get back to you shortly on the calibration ideas...I just need to get an answer from out tech and I will post it in here!

 

[Akimbo]

...I will get back to you shortly on the calibration ideas...

Any feedback? Leaving for a dive trip early Wednesday.

 

[Atomic Aquatics]

Hi Akimbo

Our Technician, Adan, made reference to a section on our website. Please refer to the FAQ section on Why I should calibrate my compass and How do I calibrate my compass. I tried to copy and paste but the black background would not transpose well. Thanks Akimbo...I hope you enjoy your vacation.

 

[Akimbo]

Thanks for getting back to me.

…Our Technician, Adan, made reference to a section on our website. Please refer to the FAQ section on Why I should calibrate my compass and How do I calibrate my compass. I tried to copy and paste but the black background would not transpose well...

Here is the link:
Atomic Aquatics Cobalt Dive Computer - Frequently Asked Questions

Why should I calibrate the compass? How do I calibrate the compass?

Any time the Cobalt is moved a significant distance on the earth- and by that we mean hundreds or thousands of miles, not just a few- the compass calibration should be redone. Instructions are on Page 8 of the Cobalt manual, which can be downloaded here.

How well the compass performs is very much dependent on calibration accuracy- even a couple of degrees off from a true 180° rotation or a 180° flip to upside-down will have an effect, so doing it very carefully is important. If you do not have the original box, as shown in the instructions, fastening the Cobalt inside a small rectangular box can help the calibration be more accurate. It is possible to do the calibration “freehand”, but since the Cobalt case does not provide straight surfaces it is necessary to be very careful to rotate as close to 180° as possible.

Problems with Compass Calibration: Most calibration problems are caused by being too close to ferrous metals. Ferrous metals can be hidden in table tops, metal supports, reinforcements in concrete surfaces, or nearby electric motors. If you experience problems with calibration vary the spot where you do the calibration.

In very rare instances, environmental conditions (mainly exposure to strong magnetic fields) might possibly require the underlying initial factory calibration to be redone. This is a service procedure that can be carried out by a qualified dealer, or by Atomic Aquatics. If careful calibration attempts fail, contact your Atomic Aquatics dealer.

You could do-away with this silly cardboard holder for calibration if you made the sides parallel to the centerline. That would allow finding a non-ferrous vertical surface to press it against and rotate. Sounds nearly impossible to re-cal at sea.

The difference in width between the widest to narrowest point is only about 0.13". It would make so much more sense if you had two molded flats per side that were square and parallel to the centerline. The pads at the narrow end would only extend ~0.065" and could be integrated into the ergonomics for improved grip.

With the continuing cost-reduction of silicon (semiconductors), you have to wonder if it wouldn’t make more sense to install a GPS chip and let it cal the compass.

 

[edgrimley]

I too ran into a compass issue today. I have several dozen successful dives with the computer - and love it for many reasons. Display, ease of use, long history, rechargeable battery. Firmware updates via Mac have gone smoothly, btw.

Today my compass stopped working. All turns were within 20 degrees of North or so. Turning 180-degrees, compass stayed at North. This was a little problematic to say the least when I realized the issue at 50 feet with about 10 feet of visibility in Monterey Bay.

I am trying to track down the original box, but not luck at this time. I carefully tried to calibrate the computer on a wood table. I still get incorrect readings. For example I am at a heading of 90-degrees, turn it 90-degrees further counterclockwise and it reads 94 degrees.

Please help. Sounds like I may be a candidate for the six step calibration?

I did nothing out of my ordinary routine this trip. No magentic ferrous materials that I know of. Same tanks, same gear, same rig setup. Although a new dive boat (to me) that I had not been on before.

RonR - thanks in advance for your help.

 

[Atomic Aquatics]

Edgrimley....Please give Adan, our technician, a call at 888-270-8595 or 714-375-1433. He can help you with your compass issue!

Atomic Aquatics

 

[RonR]

Any suggestions for recalibrating the Cobalt compass without carrying all that cardboard when traveling? Why can’t you just flip the thing over on a tabletop or held against an unreinforced block wall? It seems like the only objective is to rotate it face-up and face-down along the same centerline.

What exactly is going on with the internals using this procedure anyway? Not very intuitive to me.

Somehow I missed this thread until now, but yes, with good care it's entirely possible to recalibrate the compass by aligning a side by eye along a straight line, rotating 180°, then flipping face down along the edge of a table or some such. Actually it doesn't matter if the face up-face down are along the same centerline or not, only that it's face up and face down re. the gravitational field of the earth.

As to what is happening, it's taking the directional magnetic vectors it sees and linking that to the accelerometer data and stored internal constants for gain and offset in 360° to provide 360° compensation.

Sometimes, if the chip itself is altered by external forces like a strong magnet, it requires the "six point" calibration. This resets the gain and offset constants for the chip. It's what edgrimley needed.

We are looking at newer chips that are more integrated and provide a path to much easier calibration for the user- though they are pretty complex in a software sense. It's not possible to do calibration with a GPS though. It's not just adapting to geographic changes, you need to sense and calibrate to the local magnetic field as it is measured inside the unit. This varies in an extremely non-linear way because of the influence of the other components in the Cobalt and its case.

Ron

 

[edgrimley]

I want to thank RonR, Atomic and Adan from Atomic for all of the help in resolving this issue in June. I wound up sending the computer to Atomic which had it back to me, recalibrated and ready to go within two weeks or so. I think they even put a new screen protector on the screen.

Thanks to Ron for the quick response and insight. Much appreciate.

I have a BARE customer service interaction happening right now as well. They too have responsive, helpful. Glad to see that the Huish acquisitions have not changed anything at BARE or Atomic.

---------- Post added September 5th, 2013 at 04:10 PM ----------

Adan and team were responsive and very helpful. Thank, Team Atomic.