Poor GNSS accuracy? [Bug 8]

[mimichris]

I wonder if the 66sr was the same at beginning of its release?

No, it didn't have any problem with accuracy just the update of the CPE file which was not good, with the latest version 5.70 I didn't see any problem anymore, but I don't use it fully nor for geocaching. There are still certainly some bugs, you have to come across them.

[mimichris]

The GPSMAP 66sr was very much right on the money while the GPSMAP 67 clearly still needs some refinement, which is not unexpected.

But is it expected? The AG3335 chipset has been in use in Garmin’s smart watches (and other Garmin devices?) for over a year now…

But indeed let’s hope that Garmin will further refine accuracy and precision of the GPSMAP 67!

I think that the problem comes from the energy saving of the 67 which is too important and too demanding, it is to the detriment of its good functioning. That's just my opinion.

[Gadwin]

We recently performed a short 1 mile long walking test, GPSMAP 67 vs GPSMAP 66sr, both units displayed GNSS Accuracy Estimate of 6ft the entire time.

The GPSMAP 66sr was very much right on the money while the GPSMAP 67 clearly still needs some refinement, which is not unexpected.

GPSMAP 67 vs GPSMAP 66sr

GPSMAP 67 vs GPSMAP 66sr v1.png

So as far I see, the 5ft GNSS accuracy on the satelitte page were also a bug.

[MarkHL]

The question of the 67's accuracy comes down to how you use it. It's certainly accurate enough to keep you from getting lost in nearly every situation you might encounter. Personally, I modify Open Street Maps (cgpsmapper) with local trails and features around my neighborhood and then use that custom IMG file for most of my needs, so the accuracy of the laid track is a high priority for me, because I want my routable trails to have a high degree of detail.
Here's an example of how I'm using Garmin GPS's (Epix, 67) to lay local tracks as seen from a screenshot (BaseCamp) of a modified Open Street Map (IMG) file. Note: The maps have a higher degree of detail on the GPS's than they do in BaseCamp.

Bottom line; Right now, the Epix (watch) is laying the more detailed track. I hope Garmin can bring the 67 up to the Epix's level of performance. Given the fact the 67 has an external antenna, the performance SHOULD BE better! However, with that said, the 67 is sure a nice upgrade from my 66s.

Spoiler

custom osm.jpg

Spoiler

custom osm_inset.jpg

[Przekątny]

Personally, I modify Open Street Maps (cgpsmapper) with local trails and features around my neighborhood and then use that custom IMG file for most of my needs, so the accuracy of the laid track is a high priority for me, because I want my routable trails to have a high degree of detail.

I use a similar method, but there is a difference, I do not edit the detailed map,
but create a transparent map that contains only trails.

In the device, such a map can be used with various detailed maps.

An additional benefit is the shorter map creation time.

For less advanced users in creating maps, I suggest the IMGfromGPX program, which can easily create a map of trails.

[MarkHL]

I too use overlays with transparent backgrounds. As you stated, much easier to maintain than the base map (in the example) which has a ton of data and a lot of routing nodes. But we're off subject here... My original statement was my (our) accuracy "needs" may be different from most users who merely want a GPS for navigation and the 67 does a very good job at that. However, my (Epix) watch shouldn't be out-performing my GPS with a Helix antenna.

[MarkHL]

I too use overlays with transparent backgrounds. As you stated, much easier to maintain than the base map (in the example) which has a ton of data and a lot of routing nodes. But we're off subject here... My original statement was my (our) accuracy "needs" may be different from most users who merely want a GPS for navigation and the 67 does a very good job at that. However, my (Epix) watch shouldn't be out-performing my GPS with a Helix antenna.

However, with that said, here's an example from yesterday under a partial tree canopy (sunny, clear, dry conditions) where the 67 and Epix laid down similar tracks (Epix is blue, 67 is black).

Spoiler

SmartSelect_20230428_082117_Explore.jpg

[Nail]

However, with that said, here's an example from yesterday under a partial tree canopy (sunny, clear, dry conditions) where the 67 and Epix laid down similar tracks (Epix is blue, 67 is black).

Black is obviously taking shortcuts. Have you compared the length of the tracks?

Spoiler

67vs66sr27.jpg

[MarkHL]

However, with that said, here's an example from yesterday under a partial tree canopy (sunny, clear, dry conditions) where the 67 and Epix laid down similar tracks (Epix is blue, 67 is black).

Black is obviously taking shortcuts. Have you compared the length of the tracks?

Spoiler

67vs66sr27.jpg

Really close (normally 0.01) difference if I'm walking. However, these tracks were laid down biking and I'm using a speed2 sensor that is doing 3D distance calculations versus the 67's straight line measurements so the Epix will be longer regardless. From my experience, I suspect two GPS's won't lay down duplicate tracks even with no obstructions. Additionally, I using Smart Mode on the Epix and 1-second on the 67, so it's apples and oranges to expect them to be the same, however, the two tracks are remarkably similar.

[mimichris]

In fact it depends on the parameters of the track recording, if we choose by distance or by time, personally I choose by time of 3s which means that the track follows the path perfectly and does not cut the turns, before I was by distance at 10m but it cut the turns, it is necessary to configure the two 67 and Epix in the same way otherwise the comparison is distorted.