Interestingly I have a Garmin 5x (Big Bertha). I checked the elevation on that and it was 412 mtrs. (Should be about 60 mtrs). On the 5x you can calibrate the elevation/altitude using the GPS coordinates which I did and then the elevation was 63 mtrs as it should be. When hiking I did this regularly on the Garmin as GPS elevation can’t lie if you have a good fix ( enough satellites ). It would seem that there needs to be a software update (possibly) to the AW6 so that a similar calibration can be undertaken. You cannot rely on barometric pressure to measure altitude from one day to the next when barometric at any given point is varying. Either that or the answer may be in some as yet unwritten algorithm.
Series 6 Altimeter Discrepancies
- Thread starter StumpyBloke
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StumpyBloke
macrumors 603
Brilliant, thank you very much for confirming.
I will point the Apple engineers to this thread when I speak to them next.
Thanks again.
I will point the Apple engineers to this thread when I speak to them next.
Thanks again.
I just spoke to Apple via the chat line. I spoke to the third advisor in two days. I then got passed to someone that was more knowledgeable. I then got passed to a senior advisor. I then was asked to take a phone call from somebody even more senior that never talked anything technical at and advised that I could send it for repair with Apple ( I don’t think so as it’s only 3 days old ) or ask the seller (Currys PC World) for a replacement or a refund. I’m inclined to ask for a refund as I don’t have a lot of confidence in this AW 6. It’s a real shame as otherwise I really liked it - being my first AW after several Garmins.
StumpyBloke
macrumors 603
Shows how clueless the advisors are unfortunately. It’s not a fault as such, it’s just an incredibly poor design which I would imagine could be sorted out via software. I am so disappointed in this but I could never get rid of my Apple Watch. Well not while I’ve still got other Apple kit...
If the facility was added to calibrate the altimeter with GPS data then it would solve the problem. If a user wanted an accurate figure at the start of an activity it would be a simple matter to recalibrate. That’s how Garmin do it and there is also a setting option to auto calibrate. I do really like the watch in every other way and all my kit is Apple kit too. I will probably hold out and hope for a software update that sorts this. The elevation gain seems to work ok so until the actual elevation reading is sorted I’ll just use my Garmin 5x for hiking where I need accurate elevation data. It’s a difficult pill to swallow as the “all day altimeter” was one of the unique selling points. Additionally I’ve just downloaded an elevation app “My Altitude” which is simple and works well. I’ll use this until the issue is sorted.
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StumpyBloke
macrumors 603
That’s the exact same app I’ve got. And as you say, perfect does the job. I’ll feedback any information I get from Apple on here.
Interestingly I tested my AW 6 for the first time this morning via a Strava activity (just a simple dog walk). Elevation gain 9 mtrs which is correct and the starting elevation of as 75 mtrs and finishing elevation 66 mtrs which are both correct. It would seem that the altimeter problem is purely related to the Compass App. I can live with this until that’s sorted.
StumpyBloke
macrumors 603
I’m not sure that’s correct as when mine is playing up I get ridiculous readings within the workout app.
For example on a walk I went today, just a short one, it shows my maximum elevation of 1421 feet where in fact it’s 315 give or take.
For example on a walk I went today, just a short one, it shows my maximum elevation of 1421 feet where in fact it’s 315 give or take.
Ah yes - totally agree - when I use the Apple Work Out App I also get the same ridiculous readings but when I use the Strava App on my AW 6 I get correct readings. I suspect that the Apple Work Out App is using the same info as the Compass App but Strava is using either a different feed or GPS coordinates.
StumpyBloke
macrumors 603
Oh I see yes. The different apps are taking different readings. It just renders this new headline feature as not fit for purpose.
Well it certainly needs sorting out. Begs belief that a headline feature couldn’t have been tested properly. It’s hardly been rocket science to see how inaccurate it can be.
zerozoneice
macrumors 6502
y'all try to turn on airplane mode on the watch before starting a gps-enabled workout.
but make sure it also disables BT (check on watch/settings/airplane mode)
I'm testing a theory.
I'm getting infinitely better & accurate gps tracks and speed/elevation/pace data when no iphone is around (therefore forcing the watch NOT to use connected gps from phone)
Do you have location services turned on for compass calibration? (except motion & fitness etc)
but make sure it also disables BT (check on watch/settings/airplane mode)
I'm testing a theory.
I'm getting infinitely better & accurate gps tracks and speed/elevation/pace data when no iphone is around (therefore forcing the watch NOT to use connected gps from phone)
Do you have location services turned on for compass calibration? (except motion & fitness etc)
Already tried that - doing an activity without the phone connected (left at home). It didn’t make any difference. Also comparing the GPS track from the watch and the phone - no noticeable difference. AW 6 is known to have more accurate GPS track than previous models.
Funny old thing - my elevation this morning at my house is completely accurate at 59 mtrs + / - 5 mtrs using the Apple Compass App. I’ve not altered a thing, not unpaired and re-paired or anything. Just checked on Compass App and it’s spot on for this location. Now that has confused me. The barometric pressure has altered (risen) a bit but I can’t believe it’s altered enough and by the exact amount to give a correct reading. The plot thickens. I just checked the change in local Barometric Pressure 965 mbar to 992 mbar which equates to roughly 230 mtrs but my inaccuracy at 965 mbar the as 370 mtrs. I shall leave it switched on today - all day altimeter and see what happens.
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zerozoneice
macrumors 6502
first do a reset fitness calibration data in the watch app on the phone before leaving it to go for a walk/run.
sustain for at least 20 min.
Everytime you have a barometric altimeter, it's all down to the algorithms to get it right. Garmin has the same issues.
IMHO the two should be held separately as there's no device that i know of that gets it right in a constant way for long periods of time (days, weeks, etc.) without constant calibration. For example, Garmin's auto calibration does not work properly, meaning you have to daily manually calibrate your altimeter, which is WTF...otherwise your floor count will slowly go to hell, altimeter obviously too.
Since AW does not have built-in maps, i think it geolocates you in 2D using GPS and using the BT connection to the phone it tries to give you the elevation at your 2D point in space. So for accurate elevation, iPhone is needed. Now the algorithms come into play: sudden barometric changes (air pressure) mean either you're moving vertically (climbing/descending) or you're using a high power air dryer, or sticking your hand out of the window of a moving car, or stepping into an elevator, or, or or.....let the device figure it out by itself wtf happens.
If you're climbing a pole, you 2D point in space remains fixed but your altitude increases. How do you measure that? Only using small pressure changes due to height differences.
Again, Imho the algorithms behind the barometric altimeter are the source of all ****ups.
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Your elevation will be calculated by one of 2 ways.
By using the built in GPS chip (you will have to be outdoors for an accurate reading)
or by using the built in barometer (hopefully not both at the same time)
If the watch is using the built in barometer for elevation then your will get large errors of accuracy as pressure changes. The barometer is also used for workouts as it is very accurate for detecting small increases or decreases in height (going up stairs etc), no GPS signal is required. If however you are jogging and the weather starts getting worse( the pressure will drop) and you watch will assume your elevation has changed resulting in elevation errors.
As a very approximate guide: 1mb of pressure is equal to 10meters in height.
As pressure drops due to weather changes your watch will indicate an increase in height (and vice versa). This only happens if the watch is using the built in barometer for reference.
Disconnect your watch from your phone, go outside where there is a clear view of the sky, take an elevation reading (compare the my altitude app from the built in altimeter app). Do the same over the next day or 2 at the same point, if you are getting different readings, the watch will be using the barometer.
Either way you can disable the barometer via your phone, which in turn disables it in your watch.
I am thinking of buying a series 6 for the always on altimeter but not if it gets its readings via the barometer and if I disable the barometer will the always on altimeter still work?
By using the built in GPS chip (you will have to be outdoors for an accurate reading)
or by using the built in barometer (hopefully not both at the same time)
If the watch is using the built in barometer for elevation then your will get large errors of accuracy as pressure changes. The barometer is also used for workouts as it is very accurate for detecting small increases or decreases in height (going up stairs etc), no GPS signal is required. If however you are jogging and the weather starts getting worse( the pressure will drop) and you watch will assume your elevation has changed resulting in elevation errors.
As a very approximate guide: 1mb of pressure is equal to 10meters in height.
As pressure drops due to weather changes your watch will indicate an increase in height (and vice versa). This only happens if the watch is using the built in barometer for reference.
Disconnect your watch from your phone, go outside where there is a clear view of the sky, take an elevation reading (compare the my altitude app from the built in altimeter app). Do the same over the next day or 2 at the same point, if you are getting different readings, the watch will be using the barometer.
Either way you can disable the barometer via your phone, which in turn disables it in your watch.
I am thinking of buying a series 6 for the always on altimeter but not if it gets its readings via the barometer and if I disable the barometer will the always on altimeter still work?
zerozoneice
macrumors 6502
Fenix 6 get its readings from barometric altimeter. Inheriting the same problems described above. At least Garmin allows manual calibration based on GPS or DEM (more accurate). Beware the auto-calibration (even if it's available) does not work, meaning you constantly need to manually calibrate. A real hassle IMHO.
GPS has the worst vertical positioning, it needs to be cross-linked with something else for reference.
I.e it locates you at whatever 2D coordinates and then checks another source for elevation (usually DEM maps) at THOSE coordinates.
But yes, AW6 altimeter (and compass app) has a lot of improvement potential, esp. when having to depend on iPhone. Not once i had the surprise to see an outdoor workout start at the right elevation, then few minutes later while walking i was seeing huge differences (like +/- 70-80m) to the reality, then came back to normal. However, those values were recorded in the workout details but when exported to a platform that supports elevation correction (like sporttracks or garmin connect), they appeared normal.
@McKain Where can you disable the AW6 barometer on the phone?!
I have never heard of this.
GPS does not rely on an external reference for height. GPS devices are receive only for consumer use. All your GPS device is doing is calculating the time it takes from multiple satellite signals to be received by your device and from that calculating your exact position ( only 3 points in a 3d space are needed to pinpoint your exact location) so the more satellites you can connect to, the more accurate your position, no data whatsoever is being sent by your GPS device or the satellite for that matter.
natchkebiailia
macrumors newbie
I'm in France and my AW6 altimeter is off at least 150meters. It's been few days since I have got this problem. For me it's more the software issue or data error. Normally watch has pressure sensor that mesures current value in hPa, it should have information about the local pressure ,using GPS, (which changes every day, so without internet technically it cannot work) in order to calculate pressure different and convert to altitude( It's about -1hPa for every 8 meters gained). It's quite straight forward with those 2 data calculate accurate altitude unless both values are correct. Hope they'll fix it soon.
zerozoneice
macrumors 6502
GPS is good at locating you on the X and Y axis but sucks big time at Z axis (elevation).
Therefore you need something to crosscheck it against a given map of elevations for a given point in 2D space, called Digital Elevation Maps (DEM). Certain watches do this check, either using built-in elevation maps or calling external maps (maybe iPhone using Apple Maps elevation data)
At least this is how it is with Garmin. Worse altimeter calibration is GPS, then DEM and most accurate is manual elevation entry (you know where you are, check Google Earth for elevation at your location, enter it in the watch)
The more GPS (Glonass/Galileo/etc) satellites you have in range, the more accurate your 2D (X and Y axis) positioning is. But not necessarily the Z axis / elevation.
StumpyBloke
macrumors 603
My hpa reading has dropped by 7 to 993 and my elevation is over 300 meters out: currently reading 388 when it’s actually 86m. The S6 built in altimeter doesn’t even begin to come close.
For me it seems that any pressure drop below 1000 hpa and I can completely disregard the altimeter’s readings.
Saying that Z axis accuracy sucks big time is a gross exaggeration. Vertical accuracy is not as good as horizontal accuracy because of the geometry of the satellites. For horizontal position determination, the receiver can select satellites on all sides of the receiver. But for vertical position, accuracy suffers because all of the satellites are above the receiver. Still, vertical accuracy is usually no worse than about 1.5 times the horizontal accuracy.
michaelb5000
macrumors regular
I agree that there is error in the reported elevation when using the complication or compass app on the watch, directly related to barometric pressure changes based on weather over time, and that error is also saved in a workout in the activity app. But this error is only or mainly about displaying your absolute altitude as an initial position (ie how high above sea level you are at a given spot) and not about error in measuring your change in altitude during a workout. The always on altimeter of the S6 is significantly better at tracking elevation change than my previous S3. Tracking change in altitude is the purpose of an altimeter, so that part works fine; initial position is related to how you calibrate the altimeter, so that is the error here.
But: the apple watch does track elevation correctly and you can use and see the correct value, if you use a workout tracking app like Workoutdoors or Strava, or an altimeter app like Altimeter+ or UpHigh. Those apps can work independently on the watch without your phone and using WOD as an example, can display your correct altitude in real time in the app correctly. So the bug is that the apple watch complication is not showing the correct value for altitude, when if fact that data point exists and is available on the watch.
While the altimeter will at times calibrate and reset itself at night or at other times, I continue to believe that best way to force the watch to recalibrate the altimeter is to move it to a new location 5-10 miles away and/or up or down a significant hill (of say 300 feet/100 meters). I don't see that anyone else here has done this or said whether this works or does not work. But it works for me (it seems to reset on the return home, so it may continue the error on the trip out, but will reset at some point as it returns or after it returns the original position).
But: the apple watch does track elevation correctly and you can use and see the correct value, if you use a workout tracking app like Workoutdoors or Strava, or an altimeter app like Altimeter+ or UpHigh. Those apps can work independently on the watch without your phone and using WOD as an example, can display your correct altitude in real time in the app correctly. So the bug is that the apple watch complication is not showing the correct value for altitude, when if fact that data point exists and is available on the watch.
While the altimeter will at times calibrate and reset itself at night or at other times, I continue to believe that best way to force the watch to recalibrate the altimeter is to move it to a new location 5-10 miles away and/or up or down a significant hill (of say 300 feet/100 meters). I don't see that anyone else here has done this or said whether this works or does not work. But it works for me (it seems to reset on the return home, so it may continue the error on the trip out, but will reset at some point as it returns or after it returns the original position).
Yep - agree with all that but it is nice to have the facility to recalibrate using GPS coordinates as on my Garmin 5 x. I just recalibrate when I start an activity if I need to rely on the altitude. If it’s a long day and I notice a significant change in the barometric pressure then I will recalibrate again - simple but it works. I agree that the auto calibration isn’t particularly good.