Topic: new HP25x0 device firmware 2.0.0 released

[Gyvate]

-The relative barometer algorithm is introduced to calculate normalized sea level pressure based on absolute barometer, outdoor temperature and altitude.
- The Rel Barometer setting was changed to user entry for Altitude.
-Supports LDS01 laser distance sensors

Ambient have accepted the barometer change to be part of their firmware portion
=> V. 2.0.0 can also be installed on Ambient WS-2000/4000/5000 consoles and the automatic normalized SLP calculation will also be available

[Crankyman]

I loaded this yesterday and once I'd put my altitude in it came back to within 0.1 hpa of my previous calculated Relative pressure.
This agrees, within a few fractions, of the 4 local airfields near me so I'm happy so far 

[Gyvate]

during the cold seasons the differences may not be so big ...
or, let's better say, the difference will remain rather stable

[gszlag]

during the cold seasons the differences may not be so big ...
or, let's better say, the difference will remain rather stable

The new algorithm (SLP) is designed to provide a better representation of the "true" atmosphere, so it uses parameters that incorporate the weight/density of air. More weight/density = more pressure. The algorithm adds or subtracts pressure adjustments (corrections) depending on outside temperatures.

We know that air can be lighter or heavier depending on temperature. For example, if you have the air conditioning on in a multi-story house, the basement will be as cold as a meat locker but the upstairs bedrooms may still be uncomfortably warm. Cold air sinks because it's heavier.

At my place this morning, Mother Nature had the outside air conditioning on and it was a chilly -18C outside.

WeeWX was showing SLP = 1027 hpa
CMX was showing the same SLP = 1027 hPa

My Ecowitt display console WS3900 (with old algorithm) was only showing a REL = 1024.

So my console was "lying" to me even though it had been calibrated against a reference barometer and has the correct REL offset.

If we weigh the cold air properly (with the new algorithm),, the correct pressure is really 1027 hPa some 3 hPa higher than the display's REL = 1024.

Now we know why a fixed offset (old algorithm) can't reliably calculate SLP. It's because a single fixed offset can't compensate for changes in temperature.

So yes, the new algorithm is a big deal, especially for climates that have large temperature swings seasonally or even throughout the day.

[Platokidd]

Upgraded to the new firmware today. Adjusted to my elevation and now the REL pressure is xx.10 inhg too high.
The ABS is set to my Starpath BARO that is a few points higher than the wh32T/H/P.

Thus, I had to lower my elevation by -78 feet (928' to 850'). REL seems to be much closer to where it should be. Will see how long this holds up...

Also notice my elevation in the console changes on its own. Seems to want to set itself at 849.7' ...

Check using this website, filled in the blanks and it is a close match for now. https://www.starpath.com/calc/Weather%20Data%20Calculators/baroheight.html

[Gyvate]

Upgraded to the new firmware today. Adjusted to my elevation and now the REL pressure is xx.10 inhg too high.
The ABS is set to my Starpath BARO that is a few points higher than the wh32T/H/P.

Thus, I had to lower my elevation by -78 feet (928' to 850'). REL seems to be much closer to where it should be. Will see how long this holds up...

Also notice my elevation in the console changes on its own. Seems to want to set itself at 849.7' ...

Check using this website, filled in the blanks and it is a close match for now. https://www.starpath.com/calc/Weather%20Data%20Calculators/baroheight.html

how can your REL be too high when you have adjusted your ABS to whatever you believe is more trustworthy and correct ? The algorithm will calculate the proper normalized SLP taking into account the temperature etc.
By what do you tell what your REL should be ?

The console only offers a (theoretical) altitude if you do/did not enter an altitude (altitude - not elevation - for proper terms see https://meshka.eu/Ecowitt/dokuwiki/doku.php?id=start#how_to_calibrate_the_air_pressure_of_your_console_barometer ) value yourself. Once you enter yours, it remains.

[Platokidd]

For reference: Altitude of my starpath BARO and my new GW3000 is 928 feet. Out of the box the gw3000 matches my the Starpath Baro spot on no adjustment.
Right now both of the above have an ABS of 29.21 inHq and it's 8 deg F outside.


With ABS 29.21 and 8 deg F and referencing 2 airports and windy close by I believe my REL pressure should be around 30.22.
If I use 928 ft in the hp2560 console it reads a REL of 32.32. Changing the console altitude from 928 ' to 850 ' the REL reads 30.22

I am puzzled..

[Gyvate]

your airport, windy etc. can only be taken as reference when your barometer and the airport runway are on the same altitude and have the same local temperature. Only then you are on an isobar.
Otherwise there will be system(at)ic deviations.
When your reference barometer and the Ecowitt barometer are at the same latitude and show the same local pressure, then the REL result (of a HP25x0 console or its detached WN32P/WH32B) will be correct.
The GW3000 has this algorithms not yet implemented !!

[Platokidd]

your airport, windy etc. can only be taken as reference when your barometer and the airport runway are on the same altitude and have the same local temperature. Only then you are on an isobar.
Otherwise there will be system(at)ic deviations.
When your reference barometer and the Ecowitt barometer are at the same latitude and show the same local pressure, then the REL result (of a HP25x0 console or its detached WN32P/WH32B) will be correct.
The GW3000 has this algorithms not yet implemented !!

Agreed. That said, I still have to lie to the hp2560 consol on altitude.

[Gyvate]

your airport, windy etc. can only be taken as reference when your barometer and the airport runway are on the same altitude and have the same local temperature. Only then you are on an isobar.
Otherwise there will be system(at)ic deviations.
When your reference barometer and the Ecowitt barometer are at the same latitude and show the same local pressure, then the REL result (of a HP25x0 console or its detached WN32P/WH32B) will be correct.
The GW3000 has this algorithms not yet implemented !!

Agreed. That said, I still have to lie to the hp2560 consol on altitude.

if necessary, your "lie" will only consist of adjusting the ABS pressure that it matches your Startpath toy and the GW3000 - no altitude to be changed (unless you have it in a very different place).

[gszlag]

Upgraded to the new firmware today. Adjusted to my elevation and now the REL pressure is xx.10 inhg too high.
The ABS is set to my Starpath BARO that is a few points higher than the wh32T/H/P.

Thus, I had to lower my elevation by -78 feet (928' to 850'). REL seems to be much closer to where it should be. Will see how long this holds up...

Also notice my elevation in the console changes on its own. Seems to want to set itself at 849.7' ...

Check using this website, filled in the blanks and it is a close match for now. https://www.starpath.com/calc/Weather%20Data%20Calculators/baroheight.html

>Upgraded to the new firmware today. Adjusted to my elevation and now the REL pressure is xx.10 inhg too high.

This sounds to be normal behaviour for any SLP algorithm.. You are hitting colder temps as winter sets in where you are and it will get colder as you head into the dead of winter. 

What this means is that the new algorithm is adding additional pressure to ABS to compensate for colder denser air.

I don;t have the new algorithm installed (yet), but I did a "old algorithm" vs Cumulus MX and WeeWX SLP calculation comparison .

I fully expected that SLP readings should be much higher at -18C. I was not disappointed. My Ecowitt console showed REL = 1024 hPa and CMX and WeeWX both had 1027 hPa - a whopping 3 hPa higher.

This is what SLP calculations are supposed to do - add pressure in winter and reduce pressure in the summer.

>The ABS is set to my Starpath BARO that is a few points higher than the wh32T/H/P.

Not unusual to have an ABS offset, My ABS offset WH32B was about 2.5 hPa.

>Thus, I had to lower my elevation by -78 feet (928' to 850'). REL seems to be much closer to where it should be. Will see how long this holds up...

Hmm..shouldn't need to cheat the system. If you change the elevation, you are changing the elevation offset part in the algorithm.

>Also notice my elevation in the console changes on its own. Seems to want to set itself at 849.7' ...

Sounds like a bug or your console is moving around on its own...

>Check using this website, filled in the blanks and it is a close match for now. https://www.starpath.com/calc/Weather%20Data%20Calculators/baroheight.html

There is no input for your station pressure. Did you try the other Starpath calculator?

Which airports are you using for comparison purposes?

Assumptions:

- You have the Starpath USB baro. We will assume that you have the correct calibrated ABS.
- The station elevation is correct
- The Ecowitt algorithm (the math) is correct.

Things to try or verify.

- Windy.com has several different pressure forecast models. Forecasts are not the actual pressure values so I would not use forecast isobars for calibration purposes.
- you live in the U.S. Unlike Canada, not all METARS report SLP values making comparisons difficult. Take a look at MesoWest or other mesonets.for absent SLP values.
- try (Dr.) Stephen's Burt SLP spreadsheet that uses elevation/altitude as a variable. His site has some weird hyperlinks, so go to measuringtheweather.net, click on Downloads. Only click on the green excel icon (the underlined hyperlink does not work). The spreadsheet should provide some lightbulb moments as you can easily visualize the relationship between elevation, temperature and station pressure.
- try comparing the measuringtheweather.net spreadsheet with Starpath's SLP calculator
- you have the Starpath USB baro. try comparing its QNH calculation with the Altimeter(setting) with the METARs that you mentioned. If you are in the same air mass (pressure system) they should be very close.
- don't forget that the new algorithm is calculating 12-hour averages, so if you are using online calculators or spreadsheets, use the 12-hour average rather than the current temperature.

Let us know the results!

[Gyvate]

- don't forget that the new algorithm is calculating 12-hour averages, so if you are using online calculators or spreadsheets, use the 12-hour average rather than the current temperature.

As far as I know the algorithm doesn't use the 12-hour average (exactly speaking  (T(now) + T(now-12h))/2 ) but uses the virtual temperature of the air layer instead (what is +/- an approximation of the above equation).
As far as I can see the algorithm works correctly (the observed "spontaneous changes" only occur if you don't enter an altitude). There seems to be a confusion in terminology here and there. Best is to use the terms and definitions in the WiKi (altitude = ground elevation + height above ground) and you will be good.
You want to use different terms and definitions: welcome to Babylon.
You want to have altimeter instead of normalized sea level pressure - wish not granted

[Platokidd]

Thanks for the replies.

gszlag,

Okay, I moved my starpath usb baro and my eh32 t/h/p downstairs. 

Ground elevation = 918' + 4' for barometers location = altitude of 922' also entered in the hp2560.

temp = 22f
 
Readings:

Hp2560 = abs -28.97 rel - 30.03
Starpath = QFE -28.97 QNH- 29.95
Dekalb airport - 915' (15 miles) - QNH - 29.98 Per (MesoWest Pressure 29.01 alt -29.98)
Dupage airport - 758' (9 miles)    QNH - 29.97
Windy: used normally to check isobars for reference. Now it's a nice widespread not tight together and covers my location and the 2 airport used for reference.

I could lower my abs on the console to get a more accurate REL, this I know.
Too much trust put into the Starpath BARO accuracy of the QFE ??

https://en.allmetsat.com/metar-taf/illinois-indiana.php?icao=KDPA
https://en.allmetsat.com/metar-taf/illinois-indiana.php?icao=KDKB
https://metar-taf.com/KDKB

Checking the link below using 922' 22 deg the barometer correction should be 1.05.
Today, it matches the hp2560. Interesting.
https://www.starpath.com/calc/Weather%20Data%20Calculators/baroheight.html

gszlag, What am I missing? How do you think I should go forward with the REL on the hp2560? Or, lower the abs?

[gszlag]

altitude of 922' also entered in the hp2560.
temp = 22f

Readings:

Hp2560 = abs -28.97 rel - 30.03
Starpath = QFE -28.97 QNH- 29.95
Dekalb airport - 915' (15 miles) - QNH - 29.98 Per (MesoWest Pressure 29.01 alt -29.98)
Dupage airport - 758' (9 miles)    QNH - 29.97

Some initial comments / notes before I start crunching somemore numbers..

Don't forget to update your Starpath baro's elevation/altitude after you moved it!

Your HP2560 with the new algorithm is now calculating SLP not QNH/Altimeter (setting).

You can't compare QNH/Altimeter with SLP as they are two different things.

Both your reference METARS do not have or publish SLP so there is nothing to compare your REL to..

But..one of your METARs (KDPA) does indeed calculate a SLP value. The SLP value is not published in the METAR but is available at MesoWest or the U.S National Weather Service (Time Series):

https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=kdpa
https://www.weather.gov/wrh/timeseries?site=KDPA           

If you and KDPA are still in the same pressure system you should now be able to compare your HP2560 REL value with KDPA SLP.

Gyvate's news that the Ecowitt algorithm is not using 12 hr averages is a bit disappointing as North Americans use these averages for their SLP calculations. And unfortunately, Gyvate also tells me that Ecowitt won't do the additional QNH algorithm that I had asked for which makes barometer calibration more difficult than the old algorithm.

This means your results may not be exact.with a local AWOS/ASOS. Keep in mind that AWOS/ASOS no longer use WBAN equations to calculate SLP - not since 1992?. Since then, they use multipliers/ratios where all elevation,temperature, humidity, plateau corrections are rolled up into one number called a ratio. There is not just one ratio, there are many which are all put into a lookup table. IIRC I think there is one ratio for every 1 degree F increment in temperature. The current station pressure is multiplied by the ratio amount to get the SLP.

Bottom-line, exactly matching your SLP value with an AWOS or ASOS station SLP is going to be difficult.

> How do you think I should go forward with the REL on the hp2560? Or, lower the abs?

Since we know that your ABS value  has been calibrated against a reference calibrated  barometer (Starpath USB baro). I am assuming that when you were using the old algorithm you were matching the METARs?

I would hesitate to abandon a calibrated station pressure  in order to match an AWOS or ASOS SLP reading that uses a very different method of calculating SLP.

Currently, I am waiting for the new firmware release for the rest of the Ecowitt display consoles. I would like to compare the old algorithm with the new one and compare all these results with Cumulus MX, WeeWX.and two ,possibly three other SLP calculators.

Such a comparative  review will give us a better idea of how close or far these SLP calculations will be from each other.

[Gyvate]

to use the (T+T(-12h))/2 needs one KB more storage to keep minute based temperature available in a RAM table - which is difficult if not impossible given the HP25x0 hardware.
Logging programs which have access to historical data can do this more easily than a console - however, if their usually averaged values for the history time slices give a better result may be questioned. Even the "current" data in weewx and CMX are (usually 5 - weewx and  1 - CMX minute) averages or based on their accumulators.
Instead, by Ecowitt, the virtual temperature of the lower atmospheric air layer is used, a method also recommended by air pressure Gurus - for practical purposes it makes no difference. But it's real-time whenever a parameter changes.
Only comparing algorithms and not the related data base is imo not a solid basis for comparison.
In addition, the accuracy of the inbuilt (or WN32P) barometers is +/- 5 hPa.
No point in having a calculated pseudo-accuracy imho.

[Platokidd]

Just my take:

For us customers in the USA and probably North America the new firmware leaves something to be desired, I'm not a fan yet!

I do have a spot on ABS! However, the REL on the console is off the charts when comparing to any/most reference points in the USA.

Was more spot on with the older firmware!

[Bigfootbuilt]

Does anyone know where I can view current airport observations that show the ABSOLUTE barometer AND relative, preferable in inHg, at the same time? Even the NWS won't show absolute. Neither does Wunderground. I live within a couple of miles from the local airport but have to wait over a half hour for the hourly readings that were taken at the previous hour. By the time its public the pressure changes. They released this firmware and it spiked my barometer over .25 inches too high. They should have given us a heads up.

[Rover1822]

This is a good reason to turn off automatic updating.
A lot of us do it on all our consoles and gateways. It is not unheard of that a firmware release has issues. This is not really an issue in this case, also hard to notify console users in order to notify.

just my thoughts.

[Gyvate]

The QFE information of an airport corresponds to the local air proessure (ABS) at the runway level (FE=Field Elevation). You can compare this reasonably with your ABS pressure of your barometer only if your barometer device is at the same altitude as the ground elevation of that airfield. In addition the outdoor temperature there and at your barometer altitude and location have to be the same. Then the ABS values should be the same.
If the temperatures differ, even at the same ABS, the normalized sea level pressure cannot be compared and will be different. So, taking airport values as a reference only makes sense if you are really close to it, your barometer is located at airfield/runway altitude/elevation and the temperature is the same.
If you have a reference barometer like that Starpath USB stick, adjust your console ABS readings in the calibration page to its ABS values, enter your altitude (ground level elevation plus height of the barometer above ground) and you will be good. The actual (dynamic) offset will be the same as the same algorithm will be applied.
Und regarding deviations:
0.1 hPa corresponds to 0.003 inHg and your console displays only two digits after the decimal point.
Meaning, for 1 hPa deviation your inHg will change by 0.03
on the other hand, the barometer chips used in the Fine Offset (Ecowitt, Ambient) consoles and WH32B have a specified accuracy of +/- 5 hPa or +/- 0.15 inHg ...

[Gyvate]

Just my take:

For us customers in the USA and probably North America the new firmware leaves something to be desired, I'm not a fan yet!

I do have a spot on ABS! However, the REL on the console is off the charts when comparing to any/most reference points in the USA.

Was more spot on with the older firmware!

I don't know how you can reasonably compare your normalized sea level pressure to so-called reference points ?
Can you elaborate ? You can compare only to what is comparable, can't you ?
(Compare in the sense of having to be equal)

And how can the old offset method be more accurate or better ?

I think you have not understood the story:
with the old method you did in fact the same calculation that the firmware does now - just only once.
The new firmware does it continuously whenever a parameter changes.
It takes into account the fluctuation caused by different temperatures - just how it is properly done.

If ten people living in the same neighbourhood calculate their offset at different times, they are likely to get different results. At each time the new console firmware would produce the same result without they having to use a pressure calculator (which would also produce the same result).
Now, what is so much better with the old method/firmware ? I don't get it ...

And, if you owned a Davis VP2, the question wouldn't arise as the console just does this calculation by default.
I simply do not understand the whole discussion ...

It looks to me more like not fully understanding the rules, the methodology, the terms and the definitions.
But still engaging in a discussion about right or wrong.

For years the complaints came up again and again that the once-off offset method was incorrect, no good etc.
Now, you get a correction based on an algorithm which is used by the professional experts - and still it's not good and people keep on arguing ...

If you are still unhappy and an Ambient user, just downgrade to an earlier firmware version.
And if you want to see the pressure readings of you next airport or public weather station, connect to their website.
But don't try to equalize what can (scientifically) not be equalized.

Recently a lot of discussions about that topic have taken place and are still ongoing.
I have several times asked the question what in practical daily life is the relevance of an accurate pressure reading for a private weather station owner (as opposite to the changes in pressure over time). I haven't received an answer yet. All the parties engaged in hot discussions have fallen silent in this respect.
What's the importance ? What's life changing ... What are the health risks etc. ???
For wind, rain, temperature, humidity I understand, but what about air pressure ?
When it is so important, where are the answers ... ???