Barometric pressure data useless

Former Member over 8 years ago

Hi all,

I'm playing around a bit with some sensor data on my Fenix 5. However, it seems to me that the sensor data the pressure sensor is returning is just not really helpful.
According to the API it "returns barometric pressure calibrated to sea level" but as a user I'm way more interested in the absolute barometric pressure the sensor is currently facing. This is also the quantity the sensor is actually able to measure but somehow I don't know (yet!?) how to access the pure measurement data. Why would Garmin measure something just to scramble it and then provide only the 'scrambled' numbers to the developers instead of the real measurement values.

Can anyone tell me how I can access the absolute barometric pressure? That would be really helpful! Thanks!

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Former Member over 8 years ago +1

Wrong data

Calibrating the altimeter does not help me since I'm not interested in the pressure calibrated to sea level. This number is absolute useless for me.
I need the absolute barometric pressure…

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dcmarti over 8 years ago

Measurements are way off...

Unfortunatelly what I observed is that barometric preassure presented on the watch is way off from measurement of my weather station (which is correct I'm sure). Station says 1021hPa, while watch: 1065hPa. Hard to say how can you relay on that measurement...

jim_m_58 over 8 years ago

Make sure you calibrate the altimeter. That's used to convert the ambient reading to sea level, and what you see is the sea level pressure. I see reading on the watch that are very close to what my weather station says if it's calibrated.

Former Member over 8 years ago

Wrong data

Calibrating the altimeter does not help me since I'm not interested in the pressure calibrated to sea level. This number is absolute useless for me.
I need the absolute barometric pressure which is the actual atmospheric pressure present at a certain altitude. If the fenix 5 has a pressure sensor that is also what it will be measuring but I don't know how to get this data.

Is there a way to access the "real" absolute pressure data?

gasteropod over 8 years ago

Sorry, but I do not think that is exposed to the CIQ interface. Therefore I do not believe there is a way to obtain the true pressure from a CIQ app. This is only available internally and not to CIQ.

Former Member over 8 years ago

https://apps.garmin.com/en-GB/apps/1e896cb8-87ac-4b7a-869f-b1c053fd917d

It is possible, but currently only available for Fenix 3 and derivates.

jim_m_58 over 8 years ago

When the f5/5x/fs started shipping, and up until the 3.90 FW on the va-hr, SensorHistory.getPressureHistory() returned the raw pressure, and what I had to do what use that with elevation to convert to MSL pressure, as MSL is what people wanted to see. It's how you can watch for weather changes, etc.

If you have the MSL pressure, you could do the inverse with elevation, and come close to getting the "raw" data back.

a1234.garmin over 8 years ago

In Russia you can hear on radio and see in internet only Ambient pressure value.

I found almost useless Barometric pressure native widget, only to estimate trend and get alert on fast pressure changes.

If we take Barometric pressure, then convert it to Ambient (raw) pressure, we can get error because of temperature and height (P = Po*exp(- μgh/RT) ), unit just estimates height MSL using internal algorithms. Double conversion looks not good.
Ambient pressure can be visible only when you start activity. I vote for availability Ambient pressure in CIQ.

Former Member over 8 years ago

If we take Barometric pressure, then convert it to Ambient (raw) pressure, we can get error because of temperature and height (P = Po*exp(- μgh/RT) ), unit just estimates height MSL using internal algorithms. Double conversion looks not good.
Ambient pressure can be visible only when you start activity. I vote for availability Ambient pressure in CIQ.

I agree that converting it forth and back is not what you want to do.
But what do you mean with "can be visible only when you start activity". I don't think that makes a difference.

gasteropod over 8 years ago

There is a built in data field which can be configured, but is only available during an activity. It is not accessible any other way.

a1234.garmin over 7 years ago

Bad thing that even pressure reported by CIQ does not match the value in the data fields. Data field values match the internal service test menu however. In this menu I can see pressure in mb.