Is the MINI 2 usable for accurate on-device track logs?

[scotte]

Just wanted to post a heads up for anyone thinking about using the MINI 2 to replace another device for on-device track logs. To be clear, I'm not talking about Inreach satellite tracking, but on-device track logging.

I just picked up a MINI 2, and while I realize it's primary purpose is the Inreach features, I had hoped it would work reasonably well for on-device track logs synced to Explore.

Unfortunately, the MINI 2 is not suitable for this purpose, even when "High Detail" activity recording is enabled. I did an inaugural walk with the device, with clear sky views, and was disappointed to see that the on-device recorded track log is very low detail and bursty. This is a 1.5 mile walk that I've done many times with various devices, so I have some good reference track logs. Typically, I'd see around 400-475 track points with my Instinct 1 Solar. With the MINI 2 there were only 31 track points, and the time between them was anywhere from a few seconds to nearly 10 minutes.

Let me be clear that I was in no way expecting the same level of accuracy from the MINI 2, but I was expecting it to be better than 10 minutes between points with "High Detail" activity recording enabled. Oddly, some points were recorded within a few seconds of each other. I suspect these clusters have to do with when the GPS receiver is in active mode, then it goes idle for close to 10 minutes.

Obviously high detail track logging is at odds with preserving battery, and that's where the MINI 2 is focused - more like Expedition mode on other Garmin devices, despite being labeled "High Detail".

In summary, while the MINI 2 is great for it's Inreach features, be aware you cannot use it for accurate on-device track logging and still need to bring along a regular handheld or watch device if this data is important to you.

[GPSrChive]

Firmware version tested with?

Can you share the recorded activity?

[scotte]

The MINI 2 firmware version is 3.22.

Yesterday I had a great opportunity to compare tracklog accuracy between my trusty GPSMAP 64st and the MINI 2. Both devices were on a vehicle dashboard with the same view of the sky for over 120 miles of mostly open terrain, with a couple of miles on an off road trail in brush/trees and canyon.

The 64st was set to track method Auto and interval More Often - it recorded 3908 track points.
The MINI 2 was set to High Detail - it recorded 381 track points with intervals anywhere from a few seconds to over 10 minutes.

I emailed GPX tracklogs from both devices to gpsrchive - I did a small bit of trimming at the start and end for privacy reasons.

Here's an overview map comparing the two:

*** edited to conform with forum posting guidelines ***

Spoiler

Screenshot.png

[GPSrChive]

Even with the caveat that the MINI 2 is primarily designated an emergency tracking device, and the track saved probably would have been sufficient to locate you if SARS had needed to do so, this detail level is worse than I would have expected, especially when configured with Settings > Tracking > Activity Recording = High Detail.

Where did the GPX file you shared come from? I ask because the MINI 2 does not create GPX tracks by default, instead using the FIT file format. You wouldn't also happen to have the FIT file, would you?

[scotte]

Indeed I did not expect the tracklog to be as accurate as my GPSMAP 64st (or any other outdoor GPS), but I had expected "High Detail" to be better than this. As far as SAR goes, the on-device tracklog wouldn't be used for that purpose. Sending a message from an Inreach device (SOS or otherwise where location is sent) gets a GPS fix at the time of sending a message. I believe mapshare tracking is based purely on the configured update interval (so it might coincide with the on-device tracklog, but not necessarily be the same) - that's my best guess, anyway. It's unlikely the mapshare link (with satellite tracking) would be used for SAR purposes, but in that case it could be anything from non-existent to 10 minutes to 2 minutes depending on the Inreach plan. Garmin is not clear on exactly what they share with LE during an SOS. However, to use the on-device tracklog, rescuers would already have to have found the device.

I already replied via the email, but just to answer here - all files I sent were processed through GpsBabel for ease in trimming the start and end of the tracklog. For the MINI 2, I converted FIT->GPX. For the 64st I ran it through GPX->GPX because GpsBabel GPX XML has newlines in it making it easier to edit. As I mentioned, the original from-device files can be provided if truly needed. I would be extremely surprised if Garmin is not aware of this tracklog limitation.

[TrackMeNZ]

I have used the Mini 2 extensively for creating GPX files, there is an option to convert the file on the device under the settings. You can export an activity to GPX and copy it from the device to your PC.

Before reading this post I thought it was getting pretty good logging. I have since investigated and it seems that the device does "sleep" between external tracking points. A couple of examples are shown below and I can send the files that correspond:

Tracking file A - external tracking set to 5 mins. Internal logging points saved up to 5 spread over 15-30 seconds immediately prior to sending tracking point, then 4:30 to 4:45 to next point even when constantly moving

Tracking file B - external tracking set to 2 mins. Internal logging points saved up to 5 spread over 30 seconds immediately prior to sending tracking point, then 90 seconds to next point, even when constantly moving

Tracking file C- external tracking set to 1 min. Internal logging more evenly spread but gap every minute of @40 seconds where no recorded positions even when constant movement.

The Tracback feature advertised by GARMIN would need a much tighter data set if you wanted to use it for retracing your steps. Maybe this works better if you do not have external tracking enabled? More testing needed.

[scotte]

Before reading this post I thought it was getting pretty good logging. I have since investigated and it seems that the device does "sleep" between external tracking points. A couple of examples are shown below and I can send the files that correspond:

Thanks TrackMeNZ, good information from you!

Not to be too pedantic, but just so we are talking about the same thing with regard to what you call "external tracking" versus "internal tracking". The MINI 2 has, in my words/mind:

1. "activity tracking" aka "activity recording" aka "on-device tracklog" (my own unofficial term), and I think what you refer to as "internal tracking". The settings for this are "Standard" and "High Detail".
2. "Inreach tracking" aka "mapshare" aka "external tracking" (if I've got you right). The settings for this are timer based.

Inreach tracking (via the mapshare page) is expected to be at the configured interval, and that seems to be the case - that is fine.

Activity tracking with "Standard" detail might be timer based, every 10 minutes - according to this site wiki[1], however the manual is not specific what this actually means, and I did not do any tests with this setting.

With activity tracking in "High Detail" my expectation is along the lines of what's in the wiki on this site - "GNSS radio remains always active to enable frequent activity recording updates at the expense of battery life"[1] however in the manual Garmin only says "The High Detail option logs your location and updates the track line more frequently in the device memory than the Standard option."

Technically, "High Detail" does update the track line more frequently, however it is, in my experience, bursty rather than having a nice distribution over time, and only sufficient for a high level overview, much worse compared to other Garmin devices (including my Instinct 1 Solar in UltraTrac mode).

It would be very interesting if the on-device tracklog tended to cluster around Inreach tracking - that wouldn't surprise me based on what I see on my device, where the on-device tracklog bursts happened right around the time of the Inreach tracking. I'm not inclined to test higher resolution Inreach tracking because that would incur cost on my plan, however I could try lower resolution Inreach tracking and see if that made the on-device tracklog even more sparse. As I plan to replace the MINI 2 with a Montana 700i tomorrow, I don't know that I'll ever have the opportunity to do it.

I'll say it again, just in case, the MINI 2 is certainly biased around being a safety device having a relatively good battery life, not as an activity/tracklog recorder nor a replacement for a regular GPS receiver. It does what it promises to do well, just don't expect anything more.

This is a good discussion, and I'm looking forward to further testing, thank you!

I also forgot to mention it previously, but I did have "Multi GNSS" enabled during my prior tests.

[1]

Spoiler

https://www.gpsrchive.com/inReach/inRea ... cking.html

[GPSrChive]

It took us a few days to get some testing done and analyzed, but we are very happy with the results.

We used a GPSMAP 66sr and a MINI 2 for this test.

• The 66sr was configured to record the track log with 'Auto - More Often'.

• The MINI 2 was configured to record the track log with 'High Detail'.

Here are the results of a ~55 km test with some details highlighted:

Test Results

MINI 2 vs 66sr Example 01.png

[scotte]

Very interesting - definitely not consistent with my testing across multiple days. Was inReach tracking enabled and on a 10 minute interval during your tests?

[GPSrChive]

The 'Send Interval' was set to 5 minutes during that test.