**** EDIT - I Guess you can't get more accuracy than this?? = Sheffield Half Marathon [See screen shot] - How do I close this thread??? ****
Anyone having GPS accuracy issues? Previous Garmin was a Forerunner 235, pretty reliable in all conditions and generally on track. [without Glonass enabled] Runs with the 645 appear scribbly in places, off track, cutting corners etc and enabling Glonass makes the situation worse. I'm wearing the 645 in exactly the same position as the 235, so nothing has changed in that respect.
Just curious, in case I have a faulty unit? [presumed the 645 would be as good as, if not better than the 235]
Still gathering data on accuracy, but I suspect my old trusty FR630 is still the mature winner over my 645. That said, I've only had two runs with the 645. Early observations, on one run the 645 did lots of weird Zig-Zags when it should have been straight lines. Yet on another, it accurately showed detail of when I ran on the sidewalk vs. the road. That's pretty impressive. ciq.forums.garmin.com/.../1321401.png
Hoping it's a software glitch = fixable :-) The 235 used to get a GPS fix if I was 'upstairs' at home [through ceiling and roof] The 645 does not. It may be the same chip, but where it's mounted within the watch could make a difference?
ShezlaFunk. How long did you wait to get a fix? Do you get one outside? In "about" on the watch, if you go a few screens down, you should see "EPO". Does it say "current"?
Extended Prediction Orbit (EPO) files allow GPS devices to predict where satellites will be in the sky, which reduces GPS acquisition time. With updated EPO files on a device, instead taking 2-3 minutes to find GPS signals, it will usually take 5-10 seconds.
EPO files expire, and are usually only good for a range of 3-14 days. In order to keep the EPO files updated, sync the device regularly.
Is it better to use GPS or GPS with GLONASS? I was under the impression GLONASS used more satellites so would be better?
As my first run with 'GPS only' appeared inaccurate, compared to the FR235, I tried the 2nd run with GLONASS enabled and results were pretty poor! [Similar experiences with the FR235 regarding GLONASS] Subsequent FR645 runs are 'GPS only' and results are described at the start of this thread.
There's a lot of controversy about whether to use GPS+GLONASS or not. Unless you are in higher latitudes (like Canada or Northern Europe or Russia or Southern India or Africa) it probably doesn't help if you have GLONASS turned on and will hurt battery life unnecessarily. Ideally the satnav chip would get a fix from satellites that surround it on all sides. With a single system (GPS or GLONASS) that's probably a safe bet. But if you have multiple systems then it's possible that a couple of satellites might be closer to each other than is optimal.
I don't have GLONASS turned on, but I haven't noticed that it made things worse either. I just leave it off for better battery life.
If you are looking on the GPS route on Garmin Connect, are both the 23x and 645 set to 1 sec recording, both to smart, or 1 to 1 sec and 1 to smart? How do the distances compare?
ShezlaFunk. How long did you wait to get a fix? Do you get one outside? In "about" on the watch, if you go a few screens down, you should see "EPO". Does it say "current"?
Hi Jim, Never start a run without a fix outside and run most days. EPO = Current. Even if the track starts at the correct point, during the run the tracking drifts off. I live in a generally open area with no high rise buildings etc and am following the exact same procedure as always followed with the FR235.
If you are looking on the GPS route on Garmin Connect, are both the 23x and 645 set to 1 sec recording, both to smart, or 1 to 1 sec and 1 to smart? How do the distances compare?
Both set to 1 sec recording when 'setting up' the watch from new. Still own the FR235, so could wear both for direct comparison, although running regularly, i'm 100% certain the tracking is way off compared to the FR235.
