The Epix, I believe, has a continuous calibration mode where it uses GPS to adjust calibration along the way. Pretty sure Sunnto has a similar feature. In the case of the Epix, this functionality never seemed to work well but it had numerous altimeter issues that were never fixed.
So slightly off target for a discussion on GPS accuracy, except GPS accuracy in the vertical direction would impact this auto calibration.
By popular demand, Millwall Ward running is back for another F5X vs FR935 test- this time in really difficult conditions, where pretty much all watches I have tried have had issues.
Both were on every second recording, GPS+GLONASS
Altitude calibrated at 10m at the start of the run
F5X Stryd+HRM-Run
FR935 optical only
By popular demand, Millwall Ward running is back for another F5X vs FR935 test- this time in really difficult conditions, where pretty much all watches I have tried have had issues.
Considering conditions not unexpected. One of those situations that you are always going to be disappointed if your expectation is too high. I see the overall distance was the same to 0.1. Is that a realistic figure?
The area is a killer- especially the top bit! This is me running with a friend towards the end of today: Vivoactive HR and F5X:
http://www.mygpsfiles.com/app/#wfp90M17
Second comparison between my Fenix 5X and FR935- both watches were set to every second recording, GPS+GLONASS and worn on my left arm;
This is my usual Tuesday morning run in Greenwich park.
Fenix 5X setup- HRM-Run+Stryd, watch calibrated to an altitude of 10m at the start;
FR935 setup- optical HR only, watch calibrated to an altitude of 10m at the start;
http://www.mygpsfiles.com/app/#yt1PXMoM Note: altitude data was excellent; the optical HR sensor tracked extremely well with both Max HR and average HR having the exact same values; as a result the calories expended have the same value!
Second comparison between my Fenix 5X and FR935- both watches were set to every second recording, GPS+GLONASS and worn on my left arm;
http://www.mygpsfiles.com/app/#yt1PXMoM
To my eyes the 935 is better.
But wouldn't this be expected given that metal elements on the F5 would behave like a Faraday Cage of some sort?
https://en.wikipedia.org/wiki/Faraday_cage I understand that Garmin is using some of the metal bezel or whatnot as an "exo" antenna. At the same time that's the reason iPhones have "plastic lines" on the back to break the full Faraday Cage not because Ive wouldn't want them to be all-metal ;-)
Suggestion for Moderaror: could this thread be renamed to FR935 accuracy? Thanks!
Would prefer to keep things like GPS and OHR accuracy discussions separate as the threads will get long enough as it is.
That said on GPS accuracy not seeing anything much to be overly concerned about. Perfect - no but we are dealing with an imperfect technology so expectations need to be set accordingly.
But wouldn't this be expected given that metal elements on the F5 would behave like a Faraday Cage of some sort?
https://en.wikipedia.org/wiki/Faraday_cage I understand that Garmin is using some of the metal bezel or whatnot as an "exo" antenna. At the same time that's the reason iPhones have "plastic lines" on the back to break the full Faraday Cage not because Ive wouldn't want them to be all-metal ;-)
Anyway, that is a just an educated guess.
A Faraday cage needs to be a continuous box, or at least a mesh with holes much smaller than the wavelength of the RF, which is 190mm-odd for GPS. A long waveguide of that diameter would probably stop GPS, but it's just a ring. I wouldn't expect the F5 case to be particularly effective at those frequencies, in the same way that the plastic lines on phones are enough to allow mobile phone signals, and indeed GPS signals, to get in and out of iPhone casings. If you look at the shielding over the components inside these devices, it's all solid metal sheet, and that's what you need for RF screening.
The bezel looks a bit short to be a loop antenna for GPS at about 140mm, but working at these frequencies is something of a black art (speaking from years of building MRI/NMR coils to operate between 300 and 600 MHz) and there could be components inside the case modifying its resonance, perhaps in the coupling to the internal connections.
It seems unlikely, frankly, that Garmin's RF engineers have never heard of a Faraday cage.
