Author Topic: How to Calibrate barometer Atlas HD Display  (Read 1078 times)

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Offline cbutterworth

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How to Calibrate barometer Atlas HD Display
« on: March 21, 2019, 09:07:16 AM »
I have been running the Atlas with HDdisplay for a few days and like it.

However, I have noticed that it predicts storms during the afternoon even though the skies are clear of cloud. I suspect that given my elevation of around 6000 feet is going to throw-off how the display treats pressure swings.

I can calibrate the pressure by adjusting it up or down using the calibrate option. For 6000 feet, ambient barometric pressure should be closer to 24 inHg an offset of 5 inHg.

My question is whether that “offset amount” would be the same for all pressures that the unit reads at this elevation. In other words, is atmospheric pressure drop a linear change with increased elevation.

The reason I ask is that when I go to the calibrate tab, it shows the current reading, not the sea-level ambient of 29inHg.

Thanks,
Charlie


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Offline Neil_O

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Re: How to Calibrate barometer Atlas HD Display
« Reply #1 on: March 21, 2019, 06:17:48 PM »
You shouldn't adjust the barometer calibration on the display for at least the first 30 days.  When you first turn on the display (or following a power outage) the display enters "Learning Mode".  In theory, when Learning Mode has completed (after about 33 days), the display will automatically be adjusting the pressures displayed based on your elevation.  If there's still an offset after Learning Mode has finished, you can then make a manual adjustment to the display.  Here's a link that provides a high-level description of Learning Mode. 

https://www.acurite.com/learn/glossary/learning-mode

Offline cbutterworth

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Re: How to Calibrate barometer Atlas HD Display
« Reply #2 on: March 22, 2019, 01:37:55 AM »
Sounds good. I wondered because there’s no mention of “learning phase” in the manual for the Atlas HD display.


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Offline Jim_S

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Re: How to Calibrate barometer Atlas HD Display
« Reply #3 on: March 22, 2019, 06:42:11 PM »
I don't own an Atlas but the manual that came with my two 5in1 displays clearly mentioned the learning mode so I suspect, if it's not mentioned, it's not a feature of the Atlas.

On the 5in1's the learning mode works okay. Both of mine are within .01" of each other, often they match but both are about .1" lower than my Access, which is automatically adjusted based on my elevation and is usually within .01"-.02" of what the weather service is reporting. It would be nice to "correct" them up for that .1" but apparently it's not possible on the 5in1 displays.

Out of curiosity, when you first powered up the display what was the pressure reading with no correction? What's your exact elevation?

As far as the "forecast" feature goes, I would ignore it. My experience is that it's not reliable. If I could, I'd turn it off.

Offline nincehelser

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Re: How to Calibrate barometer Atlas HD Display
« Reply #4 on: March 22, 2019, 07:41:40 PM »
Out of curiosity, when you first powered up the display what was the pressure reading with no correction? What's your exact elevation?

My Atlas display goes to 29.92" after a hard reset, just like a 5n1 display.

Offline Neil_O

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Re: How to Calibrate barometer Atlas HD Display
« Reply #5 on: March 22, 2019, 07:44:50 PM »
Out of curiosity, when you first powered up the display what was the pressure reading with no correction? What's your exact elevation?

My Atlas display goes to 29.92" after a hard reset, just like a 5n1 display.

So does mine, even after being without power for as short as 10 seconds. 

Offline nincehelser

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Re: How to Calibrate barometer Atlas HD Display
« Reply #6 on: March 22, 2019, 07:52:44 PM »
On the 5in1's the learning mode works okay. Both of mine are within .01" of each other, often they match but both are about .1" lower than my Access, which is automatically adjusted based on my elevation and is usually within .01"-.02" of what the weather service is reporting. It would be nice to "correct" them up for that .1" but apparently it's not possible on the 5in1 displays.

You can do a manual adjust on some of the more recent 5n1 displays, but it is best to wait until the learning period has passed.

Offline cbutterworth

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Re: How to Calibrate barometer Atlas HD Display
« Reply #7 on: March 22, 2019, 10:44:55 PM »
Ok, but does the Atlas HD actually have a learning mode?


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Offline Jim_S

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Re: How to Calibrate barometer Atlas HD Display
« Reply #8 on: March 24, 2019, 06:40:28 PM »
My Atlas display goes to 29.92" after a hard reset, just like a 5n1 display.

Okay, thanks. I was hoping the display defaulted to station pressure and allowed the user to enter an elevation or offset. 

You can do a manual adjust on some of the more recent 5n1 displays, but it is best to wait until the learning period has passed.

There seems to be a lot of different displays available. I have two, purchased in December of 2016 and December 2017 respectively. Neither appears to be manually adjustable but I could be missing something.



 

anything