GPSrChive Discussion Forum

Wombo wrote: Mon Nov 27, 2023 7:47 am Some examples I've already seen here on a new device with latest V4.22:

Please confirm device firmware (software) and GPS version from your MINI 2 > Settings > About page.

Delving a little deeper here is some more detail from extra testing that adds to and corrects one of the observations from my short test.

With inReach Tracking (Send Interval) Off, and Activity Recording Standard, the device does commence logging continuous track points as I observed, however after around 24 seconds it does revert to the 10-minute logging interval as specified by Garmin.

This did not show initially on my short figure 8 course, and over a longer course the track behavior appears identical to the other observations with the inReach Tracking on. Each of the 10-minute intervals repeats the pattern of 20'ish second clusters of track points.

Detailed plot example

Standard Detail Track.JPG

My software version is 4.22 (911827) & Multi-GNSS 7.00

A test loop today accompanied by a GPSMAP66i gives another view on just how much you could be missing, net result two clusters of points over 18 minutes:

MINI 2 High Detail track compared with 66i

Test Redacted.JPG

In regard to the underlying question of accuracy and useability of the MINI 2 Activity track log - once the current bugs that hobble its useability are resolved - I've completed a test over a short variable geometry loop to quantify this.

In summary, under the ideal conditions of the test and using the "High Detail" algorithm demonstrated that the MINI 2 was capable of resolving loops down to at least approximately 6 x 9 meters, with 95% of track points falling to within less than 3.1m of the true line. It was not able to resolve my next smallest loop of 3m diameter.

This is clearly not going to be the same in typical usage environments but it's a guide. The details are in the images below and you can make your own judgment for your use case but I personally think it's very capable of being used to capture good track logs for the activities it's intended for.

Test summary plot

Mini2 Test Plot 04Dec23.jpg

Test details if you want the geeky stuff for validation

Test details 04Dec23.JPG

Test configuration

Test Configuration B 04Dec23.jpg

My apologies for taking so long to respond.

Looking at your 'Test Configuration' photo above, it appears a large portion of the MINI 2 'Sky View' is obstructed by the external antenna mounted directly above it.

Test Configuration

Test Configuration v2.png

Based on the dimensions of the MINI 2, I was able to roughly calculate the distance between the MINI 2 GPS antenna and the external antenna to be about 9 inches. I was also able to determine the angle of obstruction to be about 40°.

• With an unobstructed 180° view of the sky at MSL, the visible portion of a GPS satellite orbit would be about 39,427 miles from horizon to horizon.
• The first 20° above the horizon is generally considered unusable for satellite navigation signals, leaving us with 140° of usable sky view.
• 140° is about 78% of 180°, and 78% of 39,427 miles is 30,753 miles of usable satellite orbit.
• At the GPS satellite orbit altitude of 12,550 miles, the 40° obstruction angle covers about 8,600 miles, or 28% of the usable sky view.

The MINI 2 really needs an unobstructed view of the sky to perform well.