cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Announcements
Welcome REI Co-op Members! We're glad you're here. If you can't access the Co-op Members section of the community, click here for instructions on how to join the section that's just for you.

Hiking Apps VS Dedicated GPS

I'm trying to figure out what is the most reliable method for recording a hike (distance, elevation, time)? 

I used a Garmin Oregon 450 for most of my hiking years but the button wore out and the technology is "outdated" by this point I assume.  I bought an Oregon 650t a couple years ago but discovered it was not consistent in recording accuracy and even had a bug in the software.  Now many people are using Apps on their phones so I've started trying that by using two of them simultaneously on my iPhone.  Also, I bought the Oregon 750t recently. 

Here are my comparisons from three recent hikes (A, B, C).  The Garmin is set to 7 seconds so it would stand that it won't be as accurate but setting it to anything lower creates huge files and drains the battery quickly. 

AllTrails
A = 6.45 w/ 1190’ gain (3h32m moving; 4h05m total)
B= 4.25 w/ 550’ gain (2h58m moving; 3h55m total)
C = 4.15 w/ 770’ gain (2h43m moving; 3h43m total)

Strava
A = 6.55 w/ 1400’ gain (1h52m moving; 4h05m total)
B = 4.35 w/ 1170’ gain (1h05m moving; 3h58m total)
C = 4.9 w/ 990’ gain (1h40m moving; 3h43m total)

Garmin 750t 
A = 6.4 w/ 1400’ gain (3h05m moving; 4h09m total)
B = 4.1 w/ 1000’ gain (2h12m moving; 3h57m total)
C = 4.2 w/ 1290’ gain (2h18m moving; 3h46m total)

The Strava is way off in terms of moving time. But AllTrails seems to be off quite a bit in elevation. But Garmin still has buggy software where my "B" Track has 1588 points but if I include all of them it reports (4.3 miles w/ 1275' gain; total time 6 days 4 hours 53 minutes) but if I delete the first or last point to make it 1587 points, it reports the numbers seen in the chart above. 

Any help on which is the most accurate or why they seem to vary but not consistently from hike to hike?  

18 Replies

As an outdoor recreation writer, I get this question often. I have tried many apps, and like you, previously used a Garmin Oregon 450T (still have it, in fact) and now use an Oregon 750T.

Simply put: Your 750T has a better antenna,  and better receiver, than your cell phone. It can also be "fine tuned" by adjusting the sampling rates to improve accuracy, something else your cell phone can't do.  From a safety stand point, your 750T will last FAR longer on a set of lithium batteries (or on a charge, if it has a rechargeable battery pack) than your cell phone will last on a charge, especially if you're actively tracking with a GPS app.

I'm using rechargable Ni-MH Panasonic eneloop pro AA batteries in the Garmin. They've worked great and last for several years. I tend to agree with you which is why I've always opted for carrying a Garmin but eventually the 450 is over a decade old and which technology changing so much, it would stand to reason that newer devices (and phones) might track things more accurately. My friends started using the apps and were getting similar elevation to my GPS but their apps always indicated more mileage. I've found the apps drain about 10% battery every 60-90 minutes so they definitely are not good for longer hikes. But here is my issue with the Garmin 650 and 750 which didn't seem to be an issue in the 450... 

After a hike, I used Garmin BaseCamp to examine my route. It's a great program for analyzing sections of hikes, setting waypoints for future exploration, or just planning future hikes. But analyzing tracks in BaseCamp is where I found issues. It's where I highlight all of the points on a single track but get sometimes radically different results if I don't highlight the first or last point (doesn't matter which). Sometimes it's not too big a deal like 4.3 miles changes to 4.1 but the longer your hike the more that completely changes the data. I did San Jacinto a couple years ago with the Oregon 650t. My route (which was set to every 20 seconds back then) without the last point showed 10.2 miles & 2600' gain but when you include the last point it jumped to 14.1 miles & 2700' gain. The moving and stopped times also changed by 30 minutes. All of the hiking books show it is much closer to 10.5 than 14 miles. When I tested other hikes against book mileage, the Garmin usually matched closer when you remove the last point. Seems like a software bug that wasn't present in the 450. 

That's my only real issue with the Garmin device.  

0 Likes

Here's an explanation of why altitude gain can vary significantly. The numbers in my example may be exaggerated but that's to make a point.

Imagine you're walking on a flat surface at 1,000' elevation. A GPS isn't perfectly accurate. Every reading could be off by up to 3' in either direction.

Here's a list of successive readings: 1,000, 998, 1,001, 997, 999, 1,003,...

To the software in the GPS this looks like 0, -2, +3, -4, +2, +4. So the GPS reports a gain of 3+2+4=9 feet gain. The error in cumulative altitude gain will increase the longer you walk. Yet you've been walking on a flat surface the entire time and the gain should be zero.

Your GPS makes several readings per minute. You go for a 3 hour walk. The altitude gain readings could be way off by the time you finish. 

It would be interesting if you could repeat your experiment. The same three hikes using the same GPS devices and apps. I bet they'll be significantly different from the first set.

 

 

...Wanderer


Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.

very interesting. now I have a question, if you're tracking your elev gains, don't you want to count the -2 to +3...as a +5 gain, to the totals?  I mean, you went down, don't you get credit for going back up? or is it just gains above a 0 axis?

Anyway, I use gaia w downloaded maps and the routes I created, basically to spot check my paper maps when necessary or I'm bored.  It does provide a track with elevation stats/profile if I use it and will also do so to the route I've imported.

That said, I've never got the fascination of tracking elev gains while backpacking (or miles, frankly) "ha! I hiked 20 miles today, you only hiked 10...that must mean..."

oops sorry going down another tangent

REI Member Since 1979 YouTube.com/philreedshikes

Why bother?  says the geezer.....And consider tectonic uplift.  My general area is rising at about a millimeter per year.  No wonder my hikes are harder than twenty years ago....

 

Don't get me wrong.   GPS is a wonderful technology, when applied usefully.

Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.

Why bother?

The only reason for me is to get a rough idea relative to previously recorded rough ideas.

That said, isolated altitude readings are very useful. For example if I start out at 5,000' and my hike is 5 miles to 10,000' then it's more useful to know how high I am (or how many more 1,000s I have to climb) than to know how far I've gone. For this purpose, an error of 3' or even 30' is irrelevant.

...Wanderer


Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.
0 Likes

@Philreedshikes the -2 to +3 is incorporated in the total of 9' gained over the 6 readings. The "altitude gain" metric only counts situations where a new reading is higher than the previous, ignoring all the down segments. That's what results in the discrepancies.

I've tested this in mountain settings where I know the altitude at the bottom and the altitude at the top. The trail is all upwards with no "dips" along the way. My smartwatch as well as smartphone apps show an altitude gain that's as much as 50% more than the different between top and bottom. Even if there was the occasional dip or down section it wouldn't be able to account for that discrepancy.

Similarly with maximum speed. Say I'm averaging 3mph. Sometimes I'll see the maximum speed as a bizarre number, say 10mph. There's no way I can walk that fast. My inference is the GPS lost signal for a while and somehow screwed up the speed calculation.

Likewise with moving time. How do the systems calculate that? GPS position readings aren't perfectly accurate. If you sit down somewhere for a rest successive readings could show you a few feet apart, i.e. moving. Perhaps there's some compensation for slow movement that's intended to deal with that. If so I'd imagine each system has somewhat different criteria. So more discrepancies.

I take these readings with a large grain of salt. For me they're only good as an estimate of what I've accomplished in that hike or relative to other hikes.

Incidentally I go for a city walk every week with several other guys. We all have smartwatches. They're different makes and models. At the end of our walks we sometimes compare the distance we've gone. It's not unusual to see 20% differences.

 

...Wanderer


Superusers do not speak on behalf of REI and may have received
one or more gifts or other benefits from the co-op.
0 Likes

I believe there is some algorithm that recognizes that if repeated measurements were taken within the range of the GPS's accuracy at the time, it presumes you weren't moving.  I.E. if your accuracy rate at the time is +/- 10', and you had a sequence of measurements that were all within 10', it's going to presume you weren't moving.

It's important to realize that the only truly accurate measurement of distance is by manual means. If you really need to know within an inch how far the distance is between point X and point Y, then you'll want to walk it with a measuring wheel. Otherwise, when using a standard, consumer GPS, being off by 10 feet when you're measuring miles is of no real consequence.

When I publish an article about a trail, I note that all distances are approximate, and they were measured with a GPS. The next person who does that trail, and is using my article as a guide, will find that their distances may be slightly different, but in reality, when they get to a point as measured with their GPS, they will likely be within feet of the spot I described in my article.

0 Likes

You're correct, and the error rate (which, by the way, if you're getting down to +/- 3', you're doing real well. I typically get +/- 10') can also account for the differences in distance between a standalone GPS and a cell phone.