Earthmate and Mapshare discrepancies

This is a complicated issue, although a discrepancy of that size is unexpected.

First off, you are comparing the "last track" in Earthmate to the most recent track on your account at inreach.garmin.com. In particular, you are not comparing "total track" in Earthmate with most recent track on your web account. Is that correct?

If you are comparing apples with apples, there still may be discrepancies. And some of them will vary over time as you sync your logged track with the web site. And, sometimes, you may get unintended consequences of having old logged track data on the device.

To review, there are two types of tracking on the mini (and on all iR devices). There are "sent points". These are transmitted in more or less real time via the Iridium satellite network and show up on the web sites more or less immediately. The interval is controlled by the Send Interval on the Mini. Typically, this will be somewhat granular - for example, 10 minutes. Then there are "logged points". These are never transmitted via the Iridium network. They only show up on the web site after a sync. If you are using the Earthmate app and it is properly logged into your account, the sync will occur OTA. The interval is controlled by the Log Interval on the Mini. Typically, this will be more frequent than the send interval - perhaps 1 minute or 30 seconds or whatever.

One thing to watch out for is that the Mini keeps the logged points until you clear them or until it runs out of space. In the latter case, things more or less "wrap around", with the most recent logged points overwriting the oldest. The statistics in Earthmate MIGHT reflect the whole set of logged points, at least for "total track". To eliminate any ambiguity, you should clear the log on the device (after you sync whatever you want to keep). AFAIK, you can only do that while tracking, so you should do it just after you start tracking. To do so, press down arrow until you see the tracking widget (the screen that says Tracking at the top). Press OK. Scroll to the option Clear Log, press OK and confirm your intent.

Discrepancies due to timing tend to be much more minor. For example, if you have NOT sync-d logged points yet, the track you see on the web consists of the sent points only, connected by straight lines. Depending on your actual path, the length of this track will be somewhat shorter than what Earthmate shows at the time. This is because Earthmate is looking at the logged points, not (just) the sent points. The same is true of the distance shown on the Tracking screen on the device. It is based on the logged points, not (just) the sent points. Once you sync OTA with the web site, these discrepancies will mostly disappear.

And no, there is no way to look at the prior track stats on the Mini.

Hi - thanks for the response

I've only used the InReach Mini once for a motorcycle ride I took yesterday. So there shouldn't be any overlap or wrap around of the tracks/points. Since there is only one trip recorded, Total Track on the iOS app and the track in MapShare should, in theory, be identical. 

I was not synching points during the ride. I has logging on the Mini, but not sending. So I had to Sync up the Mini to both the iOS app, and also to MapShare via the InReach Sync app for Mac OS. Which is why I'm confused as to why the numbers don't match.

The distance travelled in the MapShare app is 9.79. Total track on the iOS app is 10.16. So it's off by a considerable amount. And the total time in the iOS app is completely wonky. Interestingly the Max. Speeds match (iOS is rounded.) Average speeds do not match, but it looks like one is moving avg, and one is total

I guess I'm curious which would be the most accurate - iOS or MapShare online. I'll make sure to wipe out the points on my next outing, but it looks like MapShare will distinguish by date, so it should be easy to keep them separate.

~m

You really should not have to use a wired sync at all. If the Earthmate app is logged into the correct account and you have cell coverage, the sync between the Mini and the Earthmate app will be propagated to the web site OTA. This has nothing to do with the distance discrepancy - just a side note which might simplify life.

Much as I hate to say it, I suspect the web site and the mobile app are never going to be identical as far as distance goes. They're both most likely getting to track length by computing the distance between successive track points and adding the results together. Depending on how much precision each carries in the coordinates and the exact way the distance is computed, the results may differ by a small amount for any given segment. The error is likely to be systematic - meaning that the "direction" of the discrepancy is likely to be the same for each segment. In your example, the web site is showing a shorter track than the mobile app. I'd expect this to be a result of the web site computing a slightly smaller distance for every segment. When it's consistent like that, the error is cumulative. The more segments (logged points), the larger the discrepancy gets.

In my experience, average speeds never match across any two sources. There are too many different ways to compute the average, and you never know which one anybody is using. Many, many forum bits have been wasted discussing just why the average speed shown is not simply the distance divided by time moving. You obviously know enough to avoid that fallacy. I'm just saying that I (personally) wouldn't expect any two calculations to match up.

I don't pay much attention to the Total screen. I can't account for the large trip time you see on the Total screen. I've been running the app and the device for some time, so I can't say if my current total trip time is sensible or not. In a quick look, it does appear to go up at real-time speed. And it never seems to get cleared no matter what I do (including clearing the logged points on the device). It also appears that the rest of the information on the Total page is the same as the corresponding data for the Current screen. But that might be an artifact of how I use the app?

Don't be too trusting of the max speed information, particularly if you ride in challenging conditions. For example, in urban canyons, along the bottom of bluff lines, near the bottom of steep hills, etc. These kinds of conditions cause multi-path reception, which can result in abrupt "jumps" in computed position. When this occurs, the apparent speed on that "jump" leg can be very high. And it gets recorded in the max speed. For example, I've been running a windowsill test for a couple of hours. 180 degree sky view, as if I was below a bluff line. Although the device has not actually moved, Earthmate shows 1.29 miles with a maximum speed of 6.17 mph. Moving average speed is 1.76 mph. The track on the Earthmate app is the classic "spiderweb" that results from multi-path motion.

All makes perfect sense, thank you again for the reply

As for the syncing to the web via Earthmate - the place I rode yesterday doesn't have great cell coverage, so I actually shut down the app - I've read stories that it depletes the battery fairly quickly, and I didn't really have the need to sync to the web real time yesterday. I tested a preset message send so my wife could see how it works.Interestingly it took about 20 mins to get to her (She's on AT&T and I know about the history of this actually not working at all with AT&T)

I bought the Mini for emergency capabilities - the tracking is something I thought I'd try - I don't really care that the two don't match up, I just thought it was a little odd that they don't given Garmin owns them both, and I am genuinely curious which is the "most" accurate. 

~m

Lots of  moving parts in SMS delivery. In most cases, the bulk of the delay is send delay on the inReach device end. You really do need a clear view of the sky to make that happen quickly. Depending on where you carry the device and direction of travel, your body can block the signal for short periods. 

There are also imponderables, such as third-party gateways between the Garmin servers and the recipient's cell network, the quality of the recipient's cell connection at the time, congestion in the cell, and so forth.