Author Topic: How does automatic barometric pressure calibration work?  (Read 985 times)

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Offline galfert

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How does automatic barometric pressure calibration work?
« on: April 26, 2020, 08:15:37 PM »
I'm posting this in the Acurite section because Acurite makes use of auto-calibration for the barometric pressure in their weather stations (at least in some of them). I know Acurite isn't the only company doing this as LaCrosse also does it. But I figure in the Acurite section this will get more exposure.

I understand how to calibrate a Davis and a Fine Offset clone station and they both use different methods. With Davis you provide the elevation and the console then calculates the offset from station pressure, simple, very accurate and precise, the way it should be. With Fine Offset you have to do the heavy lifting and figure out what your elevation pressure offset is based on your elevation, so you have to do the math yourself (one time), which is not that hard using an online elevation calculator like Kaisan. Also very accurate and precise but you need to know what you are doing (which is why I've written so many help posts on this topic).

So what gets me is how does this auto-calibration even work? I want to understand it from a conceptual view. If you can't provide the elevation to the console nor manually enter in the barometric offset then how does the station figure this out in 14 days? What is it doing during those 14 days? Is it just seeing how high and how low the barometric pressure gets and then it keeps adjusting the max and minimum to acceptable "possible" real world levels? That is the only thing I can figure. Maybe it is as simple as that. But couldn't there be some room for error if it was that simple? I just don't think that would be as precise as being able to manually enter in the elevation (or an offset). Because if it were that precise and automatically hands-off then why wouldn't other reputable quality station manufactures also not use this method?

For contrast take Garmin equipment that has a barometer/altimeter. Garmin uses the built in GPS to determine elevation and then the barometer adjusts based on GPS elevation data. The Garmin still needs time to adjust as GPS elevation data is not perfect but it gets the device into the ball park. This method of auto-calibration makes sense to me. But what Acurite and LaCrosse (and perhaps others) are doing without GPS makes no sense.
https://support.garmin.com/en-US/?faq=FhOYuggxmV6Atph276U4h8

I'd like to hear other people's thoughts on this...even if you don't know the answer. Maybe we just kick this around and we'll see where the conversation goes. Maybe we can come up with some plausible answers even without really knowing what the secret sauce is.
 
« Last Edit: April 26, 2020, 09:18:33 PM by galfert »
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Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #1 on: April 26, 2020, 08:30:13 PM »
What is it doing during those 14 days?
Good question. All I know is every time I read all these threads about the ridiculous hoops that must be jumped through, I'm glad I have Davis consoles, VP2 and Vue. Enter your elevation, select units/type measurement desired...DONE. No learning, no nothing...instant, accurate pressure. Why should that be so hard for the others to duplicate. I get headaches for you guys.  :roll:

Offline AlanD96

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Re: How does automatic barometric pressure calibration work?
« Reply #2 on: April 27, 2020, 02:29:56 PM »
What frustrates the hell out of me is that if the Atlas display powers down for even a fraction of a second, it LOSES its current barometric pressure reading. 
You then have to wait FOURTEEN days again for the thing to calibrate and figure it out.  AND there's no indication on the Atlas display, as there apparently was on earlier AcuRite stations which tells you when your display has actually finished calibrating the barometric reading.   
I love the Atlas, but this is ridiculous. 

Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #3 on: April 27, 2020, 06:00:13 PM »
What frustrates the hell out of me is that if the Atlas display powers down for even a fraction of a second, it LOSES its current barometric pressure reading. 
You then have to wait FOURTEEN days again for the thing to calibrate and figure it out. 
Utter insanity. Not just the no back-up power, but the two week waiting period is almost as ridiculous. IF I were to keep it, I'd power it with a UPS.

Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #4 on: May 21, 2020, 02:41:11 PM »
So what gets me is how does this auto-calibration even work? I want to understand it from a conceptual view.

I'd like to hear other people's thoughts on this...even if you don't know the answer. Maybe we just kick this around and we'll see where the conversation goes. Maybe we can come up with some plausible answers even without really knowing what the secret sauce is.

I was actually pondering this the other day between washing hands and looking out the window. I think their algorithm is based on the historical average barometric pressure (29.921). In the simplest form it averages station pressure for 2 weeks figures out the offset to adjust that to 29.92 and Bob's your uncle.  ;)  Of course that assumes the previous 2 weeks weather was reasonably average which is a big assumption.
Anyway that's my guess. I don't think it's a particularly good way (I prefer entering my elevation) but it does leave the user out of the equation.
FWIW, I have an Acurite 5in1 station with two consoles and an Access. Right now the upstairs console reads 29.85, the downstairs console reads 29.84 and the Access (which allows you to enter an elevation and doesn't auto calibrate) is at 29.83.

Does anyone remember what the pressure starts out at on a power up. That might provide a clue.


Offline Neil_O

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Re: How does automatic barometric pressure calibration work?
« Reply #5 on: May 21, 2020, 07:03:20 PM »
I'm pretty certain that the display defaults to a pressure of 29.92 inches Hg when the unit is powered up.  I've found that it's not a bad idea to power cycle the display when the actual pressure is around 29.92. 

Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #6 on: May 21, 2020, 08:03:30 PM »
I'm pretty certain that the display defaults to a pressure of 29.92 inches Hg when the unit is powered up.  I've found that it's not a bad idea to power cycle the display when the actual pressure is around 29.92.
It's been a while but that's what I'm remembering too. I thought about waiting until the start up pressure matched the real pressure but I was too impatient.

Offline AlanD96

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Re: How does automatic barometric pressure calibration work?
« Reply #7 on: May 21, 2020, 09:17:20 PM »
I'm pretty certain that the display defaults to a pressure of 29.92 inches Hg when the unit is powered up.  I've found that it's not a bad idea to power cycle the display when the actual pressure is around 29.92.

There is a REAL danger in just generally power cycling the display at any time.   
As many here will attest (me 3 times!), when you power cycle the display or lose power for any reason there is a possibility that you will brick your display.  Many have purchased small ups devices to keep that from happening.
OTHERWISE, your idea to reboot the device at 29.92 is really smart.


Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #9 on: May 22, 2020, 03:21:57 PM »
https://support.acurite.com/hc/en-us/articles/360007680394-Inaccurate-Barometric-Pressure
[tup] Well I guess that answers that... Kind of too bad I was hoping for a good discussion.

I would vastly prefer being able to enter an elevation rather than the auto calibrate but I'll admit they seem pretty accurate after the month is over. From the manufacturer's point of view it removes the user from the equation and probably reduces tech. support calls.

Quote
There is a REAL danger in just generally power cycling the display at any time.
I assume that's for the Atlas display...? I have two 5in1 displays which have a built in battery backup. I don't remember ever having one accidentally power down.

Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #10 on: May 22, 2020, 04:02:36 PM »
https://support.acurite.com/hc/en-us/articles/360007680394-Inaccurate-Barometric-Pressure
I would vastly prefer being able to enter an elevation rather than the auto calibrate but I'll admit they seem pretty accurate after the month is over. From the manufacturer's point of view it removes the user from the equation and probably reduces tech. support calls.
After a month? That's ridiculous. If it were maybe 30+ years ago when finding ones elevation might be a little more difficult but nowadays?
Just more "dumbing down" for the 1% who can't get it right so everyone else pays.

Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #11 on: May 22, 2020, 05:46:25 PM »
After a month? That's ridiculous.
How so?

Just more "dumbing down" for the 1% who can't get it right so everyone else pays.
No arguments from me on that. As I said, I'd vastly prefer being able to enter an elevation instead of the auto calibrate.

Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #12 on: May 22, 2020, 06:09:44 PM »
After a month? That's ridiculous.
How so?

Just more "dumbing down" for the 1% who can't get it right so everyone else pays.
No arguments from me on that. As I said, I'd vastly prefer being able to enter an elevation instead of the auto calibrate.
How so? Because waiting a month to get accurate pressure is asinine. To not be given a choice on whether you can enter your elevation or not for a weather station is frankly a stupid decision. You even said it yourself, you'd rather be able to enter your elevation, so your statement just verifies the poor decision making to not allow an elevation to be entered. Just makes for completely unnecessary headaches.

Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #13 on: May 22, 2020, 07:07:27 PM »
How so? Because waiting a month to get accurate pressure is asinine.
Says you. What are you basing it on? Facts or guesses?

My first thought after reading the description was, "is 30 days long enough?" It doesn't seem like it to me but both my consoles, which were brought online a year apart, are spot on with my Access which is set by entering an altitude. Maybe I was just lucky or maybe it actually works.

To not be given a choice on whether you can enter your elevation or not for a weather station is frankly a stupid decision.
Again, says you. In this case I agree but I'd find a way to express it without the name calling.

How about taking a deep breath, skip the name calling, and argue your position respectfully.

Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #14 on: May 22, 2020, 07:21:35 PM »
How so? Because waiting a month to get accurate pressure is asinine.
Says you. What are you basing it on? Facts or guesses?
What?? You said it yourself in reply #9....only moments ago.... "I'll admit they seem pretty accurate after the month is over." :roll:

As far as name calling, saying it's a "stupid decision" is not "name calling", it's an opinion, just like what you're expressing here. If that upsets you, that's your problem. The only reason I posted here is for some newbie that may stroll along and want to make a more informed decision if in the PWS market.

Is that respectful enough?

Offline saratogaWX

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Re: How does automatic barometric pressure calibration work?
« Reply #15 on: May 22, 2020, 07:43:48 PM »

Is that respectful enough?


Umm.. nope.  Your posts contain pointed negative remarks:

"Utter insanity. Not just the no back-up power, but the two week waiting period is almost as ridiculous."

"Just more "dumbing down" for the 1% who can't get it right so everyone else pays."

Respectful enough would be posts without the pejorative add-ons.
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Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #16 on: May 22, 2020, 08:48:29 PM »

Is that respectful enough?


Umm.. nope.  Your posts contain pointed negative remarks:

"Utter insanity. Not just the no back-up power, but the two week waiting period is almost as ridiculous."

"Just more "dumbing down" for the 1% who can't get it right so everyone else pays."

Respectful enough would be posts without the pejorative add-ons.
Negative remarks? :lol: Yes, this is YOUR world and I'm along for the ride, but evidently we grew up in a different perspective of how it should be. Frankly, getting tired of the targeted self-righteousness here. I'm not alone either...

Offline saratogaWX

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Re: How does automatic barometric pressure calibration work?
« Reply #17 on: May 22, 2020, 09:00:51 PM »
It's not my world, it's our world.  As admin, I'm simply pointing out your outlier behavior that in itself is causing the problem.
It's by no means self-righteous.  You are truly not alone in the outlier behavior as several others have been noted to have the same rush to hostility/pejorative comments.

Frankly, many are tired of your hostile comments too.  If you don't want the feedback, don't make comments that deserve the feedback.
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Offline Storm017

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Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #19 on: May 22, 2020, 09:13:51 PM »
It's not my world, it's our world. 
BS. You and your "folks" pick and choose what's acceptable or not in your "circle". God does this sound familiar....

Offline saratogaWX

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Re: How does automatic barometric pressure calibration work?
« Reply #20 on: May 22, 2020, 09:49:06 PM »
What's acceptable is in the registration agreement.  I simply point out behavior that runs contrary to that.  Your pejorative comments generally go against what is acceptable outlined in the registration agreement.

It appears you are pained by the criticism of your posting behavior.  The corrective comments are genuinely meant to guide you to correct the behaviors that are cited.  It has nothing to do with "folks" or "circle" or any other conspiracy theory.  The admins/mods here have only stepped-in when observed behavior in posting calls for it.  The only posts of yours that need feedback are the ones with negative/pejorative content and THAT is what needs to change on your part.
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Offline CW2274

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Re: How does automatic barometric pressure calibration work?
« Reply #21 on: May 22, 2020, 10:11:51 PM »
What's acceptable is in the registration agreement.  I simply point out behavior that runs contrary to that.  Your pejorative comments generally go against what is acceptable outlined in the registration agreement.

It appears you are pained by the criticism of your posting behavior.  The corrective comments are genuinely meant to guide you to correct the behaviors that are cited.  It has nothing to do with "folks" or "circle" or any other conspiracy theory.  The admins/mods here have only stepped-in when observed behavior in posting calls for it.  The only posts of yours that need feedback are the ones with negative/pejorative content and THAT is what needs to change on your part.
Your rules here on this particular forum are meant for people who are appalled by telling them their shoe's untied.

Offline saratogaWX

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Re: How does automatic barometric pressure calibration work?
« Reply #22 on: May 22, 2020, 10:23:04 PM »
No, the rules are to prevent bullies from harassing the other members.  I'm appalled that you don't seem to be able to incorporate corrective behavior feedback to your bad posting behavior so that said bad behavior ceases.
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Offline Jim_S

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Re: How does automatic barometric pressure calibration work?
« Reply #23 on: May 22, 2020, 11:48:41 PM »
Your elevation for the station is set through MyAcuRite Account.

https://support.acurite.com/hc/en-us/articles/360021409454-Manage-How-Barometric-Pressure-is-Displayed-for-the-AcuRite-Access
[tup] Exactly, but that only works for the Access not the displays (unless I'm missing something). The only option for the displays is auto calibrate. What surprises me is how accurate auto calibrate is (based only on my personal experience).

Offline Storm017

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Re: How does automatic barometric pressure calibration work?
« Reply #24 on: May 23, 2020, 12:52:16 AM »
I don't how their algorithm actually works, but after 30 days it is pretty close.  If I compare between my Davis and Local METAR, the console is only +/-0.02 off. I think that is pretty good.

 

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