My Garmin 60CSx vs. iPhone

[+Petriez]

Out geocaching today with my Garmin 60CSx and iPhone, I took a picture to show just how much better it is to have a real GPS receiver. The Garmin had an accuracy within 3m and the iPhone 0.2km.

 

[+dfx]

film at 11.

[+Prime Suspect]

While I think there's little doubt the 60 is better at being a GPS than a iPhone, you can't really go by those numbers. There is no industry standard for calculating the accuracy numbers. It's widely believed (but not confirmed) that the Garmin 60CSx means there is a 90% chance that the actual location is within X feet. Who knows what formula Apple is using? I mean, they can't even calculate the phone's signal bars right.

Edited July 14, 2010 by Prime Suspect

[+user13371]

And then you have days like this:

 

 

From log entry: http://www.geocaching.com/seek/log.aspx?LU...b6-7ba2cd734df0 ...

 

... which means ALMOST nothing.

 

Every GPS will report a position and an accuracy -- two completely different things. The iPhone's "accuracy" figure is just a measure of how confident the device is about the position report. Big number, bigger uncertainty. What really matters is when it says your position 3ft to the cache, can you reach out and touch it? Or do you still have to walk around looking for it?

 

Today was a much more "reach out and touch it" kind of day.

Edited July 14, 2010 by lee_rimar

[+Dorothy_&_Tin_Man]

Comparing an iPhone GPS to a dedicated GPS? really? Do we really need to debate what would be a better option for accuracy? Lets not even talk about accuracy in heavy tree cover. Its a phone people.

 

I use the iPhone myself and i can tell you it introduced me to this great hobby. You can not beat the ability to look for a cache in an area you never intended to hunt instantly.

 

Accurate? absolute not.

 

slow GPS? yes.

 

Easy to use and introducing many people to a great hobby who would not otherwise spend the money on a pricey GPS unit? H3ll yea.

 

I am an uber Mac fan and Macs can do no wrong (iPhone 4? shhhh) but lets be real. A Garmin is designed to do one thing and do it great. The iPhone is designed to do many things well.

[+Petriez]

My point being - No matter how much anyone tries to say otherwise, I geocache with both the 60CSx and the iPhone 3GS and the Garmin is far more accurate than the iPhone every time - I know this through experience.

 

I was rushing to grab a FTF at a new cache. In front of me was another vehicle whom I was sure was doing the same. At a t-junction, about 50 metres from GZ, he made a left turn, my Garmin said right. I stopped and found the cache. Just about to log and here he pulled up. His GPS had told him it was in the opposite direction - he had an iPhone.

 

But, I still use both because there is no true paperless caching with the 60CSx and I find the Groundspeak Application invaluable as a caching aid. I am happy to have the App with it's problems than not at all.

 

In the photo that I posted above, the cache was about ½ metre in the direction of the pointer. One factor that has to be taken into account is the fix/mark that the CO used. The posted coordinate is not always perfect either.

[+dfx]

My point being - No matter how much anyone tries to say otherwise, I geocache with both the 60CSx and the iPhone 3GS and the Garmin is far more accurate than the iPhone every time - I know this through experience.

of course. everybody had always known that, only the iphone users didn't wanna admit it. or more precisely, now that the iphone 4 is out and they see that it's got better accuracy, they now finally admit that the previous iphone's accuracy was pretty crap. of course they now claim that the new iphone's accuracy is up to par with regular handheld GPSrs. they will probably continue to claim that until there's an iphone 5...

 

that being said, getting you within 6 meters of the cache is actually pretty good. but it looks like the picture was taken in a very open area, i don't even wanna know how quickly the accuracy drops under tree cover.

Edited July 14, 2010 by dfx

[+user13371]

I don't think anyone who knows what they're talking about would ever argue that any iPhone model (or any smartphone) is as accurate as a purpose-built handheld GPS. The iPhone's GPS is more intended to find a cafe more than a cache. It is "accurate enough" for finding a lot of caches -- but that's not the same thing as saying "as accurate" as some other device.

 

But what's wrong with the OP's snapshots are that they focus on the wrong thing. The EPE or accuracy figures displayed on any GPS screen are a fuzzy estimate of confidence, not a hard indicator of how close you really are to the reported coordinates. And a single snapshot or the results of one good day of caching mean almost nothing-- repeated measurements over a period of time are the only thing you can go by.

 

My DeLorme PN-40 sometimes counts a distance down to my destination to zero -- and then goes into negative numbers. But I don't think I've ever found myself standing INSIDE the ammo box It's only the rough solution to a fuzzy math problem.

[+ZeLonewolf]

But what's wrong with the OP's snapshots are that they focus on the wrong thing. The EPE or accuracy figures displayed on any GPS screen are a fuzzy estimate of confidence, not a hard indicator of how close you really are to the reported coordinates. And a single snapshot or the results of one good day of caching mean almost nothing-- repeated measurements over a period of time are the only thing you can go by.

 

Yes, precisely, and different manufacturers use different EPE thresholds, so it gets really murky. The only comparison you can really do of EPE numbers is between two of the same device.

 

Also note that Groundspeak lists coordinates to the 1/1000th of a minute -- which I will note is equivalent to 6 feet on the latitude side. So, on average, you will get something around 4 feet of error MERELY due to a lack of decimal places, and that's something NO device can defeat.

[+dfx]

Also note that Groundspeak lists coordinates to the 1/1000th of a minute -- which I will note is equivalent to 6 feet on the latitude side. So, on average, you will get something around 4 feet of error MERELY due to a lack of decimal places, and that's something NO device can defeat.

which does not matter because no consumer-grade GPS receiver gives you any accuracy better than 9-10 feet. what's your point?

[+user13371]

I think the point was that looking at EPE or accuracy numbers -- especially below that threshold -- is a pointless exercise. See posts #3, 4, 8, 9 in this thread. And countless others on this same subject through years of discussing various models.

[+dfx]

I think the point was that looking at EPE or accuracy numbers -- especially below that threshold -- is a pointless exercise. See posts #3, 4, 8, 9 in this thread. And countless others on this same subject through years of discussing various models.

i don't see any accuracy numbers below that threshold anywhere?

[+user13371]

No? Post #1 - Garmin reporting 1ft from target and 3m accuracy. My own post #4 showing distance to target 3 feet, just to make the point. No matter what EPE or accuracy figure is posted, and distance to target is subject to the same fuzziness. Some days you might be within arm's reach and the GPS will show that. Others you could still be many paces away when the GPS says you're on top of it.

 

Any single reading - or even a small number sampling - tells you nothing useful. Ditto on one-off, side-by-side comparison of two different devices. A large set of samples over time and different conditions is the only way to grade a device. And all you can grade it on is how wide (or small) the scatter pattern is.

 

I happen to agree with the OP's main idea -- that a dedicated GPS is almost always gonna be more accurate than a smartphone GPS (I never disputed that). It's just that the anecdotal evidence presented here doesn't really back that up. I can find (or engineer) situations that would go the other way, too.

[+dfx]

No? Post #1 - Garmin reporting 1ft from target and 3m accuracy. My own post #4 showing distance to target 3 feet, just to make the point.

first of all, the garmin is showing 1 meter distance, not 1 foot. second, 3 meters accuracy (= 9 feet) is well above the rounding error you get with 3 digits after the decimal point in the minutes (which is 1.8 meters). third, the distance shown is the distance shown and the accuracy is the accuracy. if the GPS tells you a distance of 3 feet, then that's what it is in the eyes of the GPS (which btw is still above the rounding error), regardless of any estimated accuracy error and regardless of any rounding errors. which is why i asked what the point of bringing up the rounding error in the first place was. i still don't see any accuracy numbers below 1.8 meters aka 6 feet.

Edited July 19, 2010 by dfx

[+Dorothy_&_Tin_Man]

I started caching on the iPhone a few months ago and it is not as accurate as they say. It will not update unless you are moving. The say it gets you within 1-10ft but that is one a perfect day with no tree cover. I would say it is 10-50ft on average.

 

When we are hunnting for caches on our favorite bike trails the iPhone will update well after we pass GZ. frustrating and that is why I picked up the Oregon 450t this week.

 

I have also gotten lost looking for caches in the woods with my kids twice becasue the iPhone had no clue to my location. I have a regular compass but i still ended up a good distance from my car. I am no boyscout.

 

Nothing beats the iPhone for paperless caching. Being able to update everything directly to goecaching.com while walking to the next cache is a huge time saver. Being able to pull up caches at any time without PQ's is unbeatable. I call it "Random acts of Caching".

 

And to DFX comment about the iPhone users not admitting the phones limitations, I have not heard anyone saying it could hold a candle to a Garmin? The operating system for paperless caching is better but not the GPS. Just more Apple haters.

 

Now i just have to learn how to use this garmin.

[+user13371]

Dfx, I'll put it as simply as possible: A single reading is useless. A Photoshopped picture is useless. An image where an old fart like me can't tell if that fuzzy bit after the number is "m" or "ft" is useless. You got me on that one

 

But your remark "the distance is the distance and the accuracy is the accuracy" seems wrong to me. If a consumer grade GPS is only expected to be reliable to within 2 metres, then reporting a DISTANCE of less than that is below the threshold of reliability, isn't it? How is that different than reporting an EPE or accuracy figure below the same threshold?

 

The GPS is saying "Here's the point I think you're at, 1 metre away from the target. I'm confident that the number I just gave you is within 2 metres of the correct value." You and I know that both figures are the result of fuzzy, approximated math with NO guarantee of being that accurate in either regard. The individual cases when those numbers happen to be spot-on doesn't prove you have an accurate GPS, any more than ones when they're further off meaning you got a lemon.

Edited July 19, 2010 by lee_rimar

[+dfx]

But your remark "the distance is the distance and the accuracy is the accuracy" seems wrong to me. If a consumer grade GPS is only expected to be reliable to within 2 metres, then reporting a DISTANCE of less than that is below the threshold of reliability, isn't it?

no, not at all.

 

you said yourself that the EPE is only a meaningless number. if the iphone reports an EPE of 56 feet, then it's likely to be better than that. the same is true for handhelds. if they report an EPE of 3 meters, it's likely to be better than that. so there is that.

 

the GPS chip internally has much more decimal digits than what you see on the device or on gc.com. it's rounded only for display on the unit, for distance calculations internally it will still use the full precision.

 

as for navigating to a location, the GPS device will use whatever coordinates you give it. if you enter them as mm.mmm, that's what it will use and that's what it will consider to be totally precise. but if you want you can enter it as decimal degrees and that will give you higher number precision, and in fact you can get coordinates with higher precision off gc.com as well, through PQs. you won't see them on the site, but the GPS will see them and will use them.

 

The GPS is saying "Here's the point I think you're at, 1 metre away from the target. I'm confident that the number I just gave you is within 2 metres of the correct value." You and I know that both figures are the result of fuzzy, approximated math with NO guarantee of being that accurate in either regard.

yeah, so what? what are you suggesting instead? not showing any accuracy estimate at all? or moving the shown distance in steps corresponding to the estimated accuracy (i.e. 3 meters at best, then 6, then 9, then 12) and nothing in between? or maybe just showing "colder", "warmer" and "hot"?

[+user13371]

No Dfx, all I'm saying is that ALL of the displayed numbers are estimates; a best guess of the moment and rounded to an arbitrary precision for display purposes.

[+dfx]

No Dfx, all I'm saying is that ALL of the displayed numbers are estimates; a best guess of the moment and rounded to an arbitrary precision for display purposes.

well, we all already know that. but that doesn't mean that the numbers are meaningless.

[+Dorothy_&_Tin_Man]

Wow, the more I learn about my Garmin (the first GPS unit I have owned), the less I believe I will be using my iPhone at all. The family and I are new to caching so we are by no means fast at finding caches but the Garmin is waaaaaay faster in the field.

 

I think we lost focus on the thread that started out as a Garmin vs iPhone and turned it into the overall accuracy of the entire GPS infrastructure. I placed my GPS on a few caches (everyone does when they get a new unit ) and it was in the 2-4 ft range. To me, if I can't find something withing that range then I really suck or the person who hide it did a great job. I'm confortable with the Garmins accuracy and I could live with the iPhones accuracy but on a hunt the speed and seeing me in tree cover is more important . That's where the iPhone fails.

 

I'm glade Grounspeak screwed up the update of the iPhone app so that the phone was unusable for caching, otherwise I may never seriously started looking at new a GPS. Behind every cloud there is a silver lining.

[+user13371]

...fuzzy .... doesn't mean that the numbers are meaningless. ...

 

No, fuzzy just means fuzzy -- and you shouldn't infer TOO MUCH meaning (or precision, in this case) from an estimate. Even worse to infer the overall quality of any GPS from a very small sampling of those fuzzy estimates -- which is what the OP and many, many folks try to do.

[+Prime Suspect]

No? Post #1 - Garmin reporting 1ft from target and 3m accuracy. My own post #4 showing distance to target 3 feet, just to make the point.

first of all, the garmin is showing 1 meter distance, not 1 foot. second, 3 meters accuracy (= 9 feet) is well above the rounding error you get with 3 digits after the decimal point in the minutes (which is 1.8 meters). third, the distance shown is the distance shown and the accuracy is the accuracy. if the GPS tells you a distance of 3 feet, then that's what it is in the eyes of the GPS (which btw is still above the rounding error), regardless of any estimated accuracy error and regardless of any rounding errors. which is why i asked what the point of bringing up the rounding error in the first place was. i still don't see any accuracy numbers below 1.8 meters aka 6 feet.

I've had an EPE reading as low as 4' before.