How accurate is the Edge 530 GPS?

Here's a quick ride I did while waiting for a friend to arrive at the trailhead. You can see the Garmin track follows the trail pretty well.

I have GPS + Glonass enabled.

Garmin Connect

I’m hoping for more of this:

And less of this:

As you can see, I’ve done some trails twice. 

Zoom in and see how closely the GPS track follows the actual trail.

Garmin Connect

That’s impressive.  That’s the kind of performance I’m hoping for.  

I'm happy with the 530.

No GNSS service is going to be 100% accurate, 100% of the time. Obvious interference like trees and buildings may affect the signal, as will reflections, but also elements in the atmosphere/troposphere/stratosphere (a previous job of mine was involved in the offset measurement of GPS from these sources). The good thing about the 530 is that it supports GLONASS and Galileo services in addition to GPS which (I've found) does improve startup times and accuracy (unless going through a tunnel) as it will adjust which service it uses to help improve the location output. I'm not sure about iphone, but Garmin devices do offer a level of configuration to trade off battery and accuracy (per second/smart) which should also help with accuracy.

I definitely don’t expect 100% accuracy and understand that canopy and ravines can impact  accuracy.  However, as I mentioned, there are posts on this forum and other (dated now) that have people complaining about their 530 being as much as 20% off the mark on know distances or compared to other devices.  I’m hoping this issue has been resolved and that the 530 is as accurate or better than my Tactix.

Here’s another comparison between the iPhone / Strava and the Tactix uploaded to Strava.  I had no idea my iPhone’s GPS was so poor.  Before I thought it was because I had it in my backpack but I’ve since switched to a hip pack.  I had the phone in the outer pocket so it shouldn’t have had any issue with the satellites.  The Tactix was on my wrist under my soft shell which was under my glove.  If the Edge 530 is as good as or better than my Tactix I think I’ll quite like it.  

iPhone GPS:

Garmin Tactix Charlie GPS:

I have done some analysis with extracted GPS data, there is GPS drift or GPS prediction, as your moving GPS data is semi-predicted by know what direction your moving, when you take a sharp corner especially MTB where you have ruts. what I noticed with aggressive turns the GPS followed a straighter line and then adjusted back to the riders line. On my test I did multiply laps on the road bike, the faster I went the GPS would drift. riding on the road right to left direction on a descend & speed color is described in the key at the top of image in Kilometres/hour, the ride is from Nov 2020 using GPS+Glognass Edge530 headunit