GPS Accuracy Issues on Enduro 3

3591619 said:

This makes me think that the inaccuracy depends on the software problem.

I doubt it is a software issue. If it was we'd also see complaints about GPS accuracy in the Fenix 8 forum because the software is exactly the same between the two watches. But there are none.

I think the key difference is in the GNSS antenna design and more specifically the lack of metal backplate which serves as ground plane for the antenna in Garmin's design of using the metal rim of the watch as the antenna. I explained that further up in this thread, but my comment got buried. GPS signal is circular polarized, and having an extra plane in the antenna may be important to improve rejection of reflected signals. I suspect that signal reflection is the cause of shifting the position to the left. That's where the watch face is generally facing when wearing the watch on the left hand. Since reflected signals travel a longer path, for the watch it may appear as if the current position is further to the left than it actually is. A good antenna design is supposed to help with that because on reflection the direction of the signal polarization flips. But perhaps what Garmin has in Enduro 3 isn't effective at that.

One of my friends has got a F8 and says that GPS in autoselect is bad and less accurate than F7xpro (he says that GPS of F8 is good enough with multiband). 

I don't understand why some bloggers and sites (DC Rainmaker, for example) say it is accurate (they use the watch also in urban areas). Are the standards good? Or is the project of this watch wrong? It is strange...

Furthermore I did not find a comparison between E3 and F8 (tracks with autoselect and multiband).

3591619 said:

I don't understand why some bloggers and sites (DC Rainmaker, for example) say it is accurate (they use the watch also in urban areas). Are the standards good?

This is from DC Rainmaker's Enduro 3 review: 

IIf you zoom in and look carefully, it is clear that Enduro3 and Fenix8 are not as good as Epix Pro in this example. But this is what he calls "spot on"!

I have seen this review: I don't like inaccuracy.

But I see that F8 is less accurate than the others in some points (the track, for example, is over the buildings). Is Epix the best watch in that photo?  

I understand that perhaps the chip of E3 and F8 is worse; in F8 the metal plated back can help, as you show. But some users say that F8 and E3 work good... Aren't they demanding? Sorry, I want to understand. 

I was enthusiastic about the purchase, but I start to feel disappointed...

I chose E3 because it does not have a metal plated back, I never thougth that might have influence over the GPS. 

I’m not a specialist, but Forerunner 965 has also a plastic back and GPS in it works fine. 

I don’t find the plastic back theory plausible - as you say generally if anything the Forerunner 935 onwards have slightly better accuracy than their Fenix counterparts. Even Garmin admitted this iirc?

what we do know from a recent teardown is that Garmin changed GNSS chipset supplier and to me Occum’s Razor suggests that is likely to be the root cause - it simply is not as accurate as the previous chipset.

There is precedence tor this too - when Garmin switched from Mediatek to Sony for the Fenix 6, tracks were often offset to the left. As UK road races are run on the left hand side, this meant that distance was over-estimated vs. UK athletics official measurements due to the extra distance running bends the offset added if running a clockwise circular route. On straight courses, the offset didn't add or subtrack distance. 

(i was the person who posted the stone circle comparison Q3 last year and it never improved since then - tracks mostly good with unexplainable offers in what are favourable conditions)

I find the tracks mostly good but clearly not as good as the Epix Pro my side which is probably Garmin’s best ever effort for GPS accuracy imho.

Rafgan said:

I’m not a specialist, but Forerunner 965 has also a plastic back and GPS in it works fine. 

Forerunner series have a different type of antenna that is more complex than just a metal bezel. It is likely more than one piece inside the body. 

Here's Garmin's patent for metal bezel used as an antenna: https://patents.google.com/patent/US20140225786A1/en

If you read it, it specifically mentions "lower surface configured to contact a wearer's wrist" as an important element of the patented design. The patent text repeats that more than once. 

But Garmin made plastic GPS watches long before it introduced Fenix series, and those use internal antennas that have multiple elements (for example dipole consisting of two elements), which is obviously not possible when you have a massive solid metal bezel. 

Idk how it works but if you switch to a new product/supplier the chip in this case , you make prototypes don’t Garmin engineers go actually outside and test this for at least 100 km ? You get a better deal maybe cheaper but come on why are they doing this and how aren’t they building on previous success … I just cannot comprehend this sitting in forums and wasting my time