Can someone explain why this oddity about InReach Mini 2?

Have the unit, wanted to see how quickly power drops, how long to recharge.

I am let it "track" on GPS sitting in the same place on a table. But apparently it has moved .12 miles in 40 minutes while in the same place. Does the shifting of GPS satellites cause such variation in location? I suppose as long as GPS coordinates report correctly, is OK. But this suggests that when is use on the trail it *could* report distance inaccurately.

Just seems odd.

 

Any inaccuracy in its position will be represented by movement. If it’s inside on a table it is very likely that its position confidence is quite low as it has limited connection with the satellites. It might see one or two which is an inaccurate position estimate, then lock four or five and be accurate to within a few meters, then drift out when it loses satellites, etc.

 

The difference in distance is considered GPS drift. Garmin says accuracy is up to 33ft. Also agree with above if it’s inside on a table it’s not the best.

Is multi-GNSS enabled? That will give you the most accuracy at the expense of battery life.

 

just to beat a dead horse, the unit is meant to be used outside with a clear view of the sky to be able to report accurately. It states this when you first turn the in reach mini on. We have 2 and we use them often. Obstructions of the sky may provide the incorrect coordinates. I have seen this when I am in deep canyons with only a very tight view of the sky. Tree lines, unless very dense, do not provide as bad reports as dense rock.

 

Thanks all. Since the distance error is so small and it was mostly to burn some battery for recharge test (damn quick recharge!) I will use different parameters, like "outside, clear view of satellites", if I try this again. Else I will stop being stupid and use it like it SHOULD be used.

 

If nothing else you can be confident that your location within a quarter mile will be reported to rescuers even if you’re in thick cover with limited view of the sky.

 

1/4 mile accuracy within what could be vast area is always better than shouting for help.

I have a Garmin Instinct 2 watch to compare distance. The watch is nice but does not send messages to satellites, so the Mini 2 serves an emergency function.

Need to stop my introductory test and get on with AZ trail testing ... in 110 degrees with sun.

 

I had friends that have to use them..... some for rescues.... others for recoveries ... after you press the button and contact is made. You have the option to communicate with SAR. Make sure that you set up your phone app and that you test it every time you go out on an adventure. I test it by sending a message to my emergency contact and ensure that they receive it. Also have your contacts and some quick messages configured. You can configure you account for someone to access and view your location on a map. Did I mention that you have to test it every time you go out on an adventure? This is important as you dont want surprises when you get into trouble.

 

Like others said, most likely an issue because it’s inside. Also, it’s not being used for navigation. They will find your body soon enough even if off by .1 mile.

 

The GPS receivers in consumer electronics are quite accurate, but there is still some error. Each reading might be accurate within 10-50 feet, typically. The motion of the satellites is part of it; there are other factors too, but the intrinsic accuracy of GPS is incredible--less than a few feet with good equipment, and possibly even higher for military applications.

The problem here, I suspect, is that that your unit is integrating its distance value over consecutive position readings, all of which contain small errors, despite the receiver being stationary. Think of it like this: every few seconds, you get a new coordinate within 50 feet of where your stationary receiver is sitting on that table. But if you actually walked to that new coordinate each time, every few seconds for 40 minutes, you may well walk 0.12 miles. That is likely why the distance seems so large.

But each reading is still within 50 feet of the receiver, the whole time. So there is nothing to worry about, unless you are trying to accurately measure distance travelled, which becomes increasingly difficult at slow speeds for this reason.

GPS receivers can combined with accelerometers or other data streams to reduce this integration error, but at the end of the day even raw readings are totally adequate for most applications. Especially figuring out where you are.

And contrary to thread sentiment... while 1/4 mile accuracy is likely adequate for search and rescue if you are alive and capable of signaling your rescuers... there are countless cases of it taking S&R multiple days to find a body within 1/4 mile of the descendant's vehicle. So for this reason, I recommend remaining alive for as long as possible, should you need to call for help with your inreach or similar device.

 

I've always figured my inreach is so they can find my body. My wife wants a body so she can get the insurance. Priorities.

 

My Garmin Instinct watch captures satellites faster if used on a regular basis, like "every day". If used every 5 days (as can happen deep winter or deep summer) it takes longer to re-find the satellites that have "drifted". After work today I can try it in "real" conditions.