Calibración automática del barómetro

[z3us]

Dar la opción de usar los archivos DEM o el servicio online para obtener la altitud, en vez de tener que introducirla manualmente cuando calibramos el barómetro.

[orux]

Dar la opción de usar los archivos DEM o el servicio online para obtener la altitud, en vez de tener que introducirla manualmente cuando calibramos el barómetro.

Ok,



buena alternativa,



orux

[z3us]

¿Es lo que hace la opción "Auto" de la calibración del barómetro?

[capoccia]

Good idea. I suggested it in old forum!!!!

Autocalibration barometer by DEM when starts "rec track"!

[orux]

Good idea. I suggested it in old forum!!!!

Autocalibration barometer by DEM when starts "rec track"!

Remember that the DEM files can also have significant errors.



I think the best option is still to use GPS in an open space, standing in the same place 1-2 minutes. OM makes the best average of the locations received.



Maybe someone can do tests on a point with a known altitude!



The height provided by the DEM files can be viewed on the control panel, if it is enabled.





orux

[6745th@web.de]

I would also prefer calibrating the altitude via the dem files. The GPS altitude is on my Samsung s4 often not very good. The dem altitude is mostly much better.

Thanks Thomas

[Maki]

What's the point of calibration via DEM? Just use DEM data directly...

[fabrylama]

What's the point of calibration via DEM? Just use DEM data directly...

You mean using dem altitude instead of barometric altitude for the whole track?

The point is the dem data lacks precision but have a good accuracy, while barometer data are very precise but, if not calibrated, isn't accurate.



Usually the dem altitude error is <10m, so can be a good calibration source for the barometer. However dem is not a good source (compared to the barometer) for the track's elevation profile, because barometer error is usually <1m when calibrated (and in good weather conditions).

[Maki]

Well, yes, if you are doing stats the barometer is better. I don't really care about stats, but I like to have both DEM and the barometer, the former to explore and read the elevation of distant points (it's faster than using contour lines), the latter to read my elevation. As Orux says DEMs can have significant errors, so I prefer to calibrate the barometer with something reliable and constantly check it along the road when I have a reference.



What I think could make the calibration dialog better is having the current value proposed as a default, and the ability to change it swiping up or down without actually entering a numeric value.

[6745th@web.de]

For me it would be perfect to have a setting in the preferences "adjust the barometer by dem at track start" and in  the calibrating dialog, adjusting by GPS, by  Dem or manually,(prefilled with dem)

I am logging my tours with mytourbook, and there I want to see how much did I climb this month/year. The best results I get with the barometric altitude. The GPS altitude is the poorest source... Dem is not bad, but barometric is significant better.

[Wolpertinger]

How about this idea for a fully automatic GPS based calibration during runtime:



1. Use height data from GPS to calibrate barometric height on the fly

-> Here starts track

2. Calculate barometric height

3. Retrieve GPS based height and calculate difference between barometric and GPS height

4. Add the value divided by $COEFFICIENT (maybe 50) to barometric height and use the result as new base

5. Got to 2.



In this way you will start with a height that has the maximum deviation of the GPS signal received. With every measurement the barometric height will drift a bit towards the GPS height, but the jitter of the GPS signal will not show up in the data, provided the coefficient is high enough.

You basically do a continuous recalibration over time without having to wait for 4 minutes in one place. Additionally you constantly compensate the drift of the barometric measurements due to changing air pressure conditions.

An additional idea would be to increase the GPS polling interval and/or decrease the coefficient at the start of the track until the mean deviation between GPS and barometric height goes below a certain limit.

As bonus, of course DEM data could also be brought into the calculation instead of GPS (especially for the initial calibration).



Hopefully the idea is clear and has no significant flaws. I think it shouldn't be all to hard to implement and would make using the barometric height sensor a lot more convenient if there is no need to manually calibrate it. Especially for longer tours it might even prove to be more accurate than barometric measurement alone.



Regards,

  Wolpertinger