GPS Accuracy

A drive on some side streets, and some on the highway, and I now have a perfect track. Faulty, or marginal hardware in the previous unit, I'm guessing.

Seems highly likely. There are bits on the track you posted previously which were a good 300 metres out. Driving is pretty good for GPS accuracy, because the high speed makes it easier for the device to reject reflected signals.
It might be a good idea to edit your earlier post to point to this one, or at least to comment on the replacement being better, otherwise people will endlessly be citing it as 'normal' behaviour for an F5.

I meant to send this last night, but fell asleep. Luckily the text was still there.

Updated information to follow!

On that particular test, I waited until it went fully green (the circle), then it cycled to red, then back to green (strange, right?), and I waited for a good 30+ seconds after obtaining green.



Has anyone seen the antenna placement/orientation in the F5? Regardless, new information.


As a followup to the test I did this morning (yesterday) with four devices, I set the F5 to GPS+GLONASS with 1 second recording. I fired up an activity (walking) and waited until it had GPS lock and indicated it was ready to start. Same drive, but in reverse. Same crappy tracks. Not content with horrible tracks I decided I'd roll the dice and try a different unit. Back to REI for an exchange. Replacement unit unboxed in the car, setup quickly and synchronized to GC on an iPhone. I set recording for 1 second, and left GPS at default. Recording started after GPS circle went fully green. A drive on some side streets, and some on the highway, and I now have a perfect track. Faulty, or marginal hardware in the previous unit, I'm guessing.


Interesting observation from the first F5. I initially set it up through Garmin Connect, then paired it with GC on iPhone. Wanting to see how quickly it could get a lock, I went outside (clear, open sky) and went into an activity; no dice. It never got a lock, even after 5+ minutes. Came back inside and deleted the EPO.bin and let Garmin Express download a new one. Back outside, fire up an activity and got lock quickly, but loses lock, then locks again. Strange...

Clearly faulty hardware, most likely the antenna that didn't allow the gps chip to download live ephemeris data but hung on with the canned ephemeris data. Poor QC at that kind of price point...

Olu, I tend to agree with you. Only starting with the fenix 3, did I spend so much time looking at GPS tracks and measuring exact run distances to check accuracy. I also agree that the feature set now available is getting pretty great (Add onboard music and running power and it would be perfect) and in combination with the design it is a really great watch.

Where I might diverge a little is that, while I agree I only scrutinize GPS tracks and data recently, when I bought my 735XT I headed down the same path, and a thread started on the 735XT forum. I only tested a few times before I was convinced the track accuracy and distance accrual with the 735XT were as good or better than any previous watch I had used and the thread died after only 2 pages I think.

Should have my f5 in hand in a few hours and will see how it compares to my 735. Hoping it is close as I really like the look and new features of the f5 :)

Only starting with the fenix 3, did I spend so much time looking at GPS tracks and measuring exact run distances to check accuracy.

Same with me. I was extremely pissed off with the accuracy of the F3. After some exchange units and some updates everything became better and one could start running instead of gps tracks watching.

Now I look at the tracks again, just to make sure that the accuracy is ok to be in the time window for a return. Everything was fine (not excellent, but fine) and I start enjoying the watch. I expect the 935 to be more accurate and can even swith to it because I am still in the return time window but I think I will stay with my F5.

Looking back at old tracks of my 310xt and 910xt makes me wonder why these watches are claimed to be "good" gps devices. Their tracks also do not look nice every time.

For me, the F5 is like a F3 without teething troubles and other children diseases combined with a better size factor. So far, so simple!

I for one have only looked at tracks because the 1k laps have been irregular compared to the FR235 and when you're fighting through a 16k marathon pace session this is quite annoying and disconcerting. I've seen wild swings from 4'15 to 4'35 for a lap vs the 4'20/4'25 I'm pretty sure I'm running and the FR235 agrees. Frankly this is not acceptable at that (or any really) price point, why deal with that type of uncertainty/aggravation?

If the FR935 has clean tracks we'll know it's the casing.

I for one have only looked at tracks because the 1k laps have been irregular compared to the FR235 and when you're fighting through a 16k marathon pace session this is quite annoying and disconcerting. I've seen wild swings from 4'15 to 4'35 for a lap vs the 4'20/4'25 I'm pretty sure I'm running and the FR235 agrees. Frankly this is not acceptable at that (or any really) price point, why deal with that type of uncertainty/aggravation?

If the FR935 has clean tracks we'll know it's the casing.

Then return the F5 and stick with the 235.

I know that I've had more wtf? moments regarding pace with my older watch then the F3.

Doesn't matter which GPS watch Instant Pace is garbage. Only way to get good Instant Pace if you want it is to use a foot pod.

We should know soon about the 935. A couple of UK guys are reporting they have theirs including Tim Grose, who also has a 735XT I believe for comparison.

I'm probably going to go with the 935. In video it looks nicer then I thought, kind of like a larger F5s. If my F5 was working like it should I'd probably keep it, but for $100 less then the F5 ($200 if you consider wifi), I can justify a device that doesn't function (for me) as advertised.

I'm probably going to go with the 935. In video it looks nicer then I thought, kind of like a larger F5s. If my F5 was working like it should I'd probably keep it, but for $100 less then the F5 ($200 if you consider wifi), I can justify a device that doesn't function (for me) as advertised.

Olu - I must have missed it. What's the problem with your F5? So far I'm happy with mine.