Distance showing wrong during the run but correct after saving????

Anyone guys? Shall I return the watch?

Can you post links to both activities? Can you see any difference in the recordings? When you say you saw differences was this looking at the distance data field? If so, did the distance start of the same and get progressive worse or jump at one time? Are the splits in the same time on the recordings.

More information needed!

CW

Can you post links to both activities?

Yes I can. I will make it public for now.

Edit- Made it private again.

Garmin 230-
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Polar M400-
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Can you see any difference in the recordings?

Well the Garmin starts GPS recording 100-150m later from where I actually started. I am trying to match the splits between the PolarM400 and Garmin230 but not all splits seem to be clearly marked by Garmin. For example I don't see any 2 and 3km marker. I see 4km marker then nothing till 9km marker...it seems like it shows the flag after every 5km? Lack of option to make the Garmin map full screen like the Polar map is highly irritating too!!! Really WTF?

When you say you saw differences was this looking at the distance data field? If so, did the distance start of the same and get progressive worse or jump at one time? Are the splits in the same time on the recordings.

Yes I was looking at the distance data field. So when PolarM400 for example showed 10kms under current distance, Garmin was showing 6 or 7km as distance (from what I remember). Garmin was consistently showing I think 2km less and gradually increased to around 3km.

The 10-11km mark is 100% accurate on PolarM400 as Google shows that to be similar distance (independently checked). If memory serves me right the Garmin at that point showed distance field as approximately 6.9km.
After 10-11km I entered a hill to do training hill repeats.

Thanks for any help or advice.

Ok so I was finally able to compare PolarM400 map with Garmin 230 map....for each and every km. I had to open the Garmin map on my mobile phone as on it I could see each and every split (on desktop only every 5kms :mad:).
The Polar and Garmin map matched very closely. The slight difference was due to Garmin missing the first 100metres or so.

Still not clear why during the run the Garmin DISTANCE field was showing 2-3kms less than Polar :confused: It is almost as if after saving the run, Garmin autocorrected everything :confused:

Well I will be running the same 29kms in couple of days so I will see what happens.

When you started your run, was the GPS signal strength coloured grey or green? If green then it had acquired satellites. When I did my first run with mine, I didn't realise mine was grey so the first 2 or 3 km went really weird. Also were you surrounded by tall buildings/trees or out in a good open area?

When you start a run from the same location more than once, the Garmin should pick up the GPS signal very quickly as it remembers your locations, so that might help in future. Did your second run work out any better on the accuracy front? If not, it's worth putting GLONASS on to see if that helps, and definitely set it to 'every second' regardless. You won't really notice any difference in battery life and any difference there might be is worth the sacrifice in my opinion. I run 5-10km a day 5 days a week and my battery will always last a good week (if not longer) before needing to be topped up (I don't use GLONASS though).

Hard to tell for sure without seeing the activities but most likely poor GPS fix.
Smart or every second recording is going to have no impact on whether you had a good GPS fix or not.

Final UPDATE-

I have been on few 30km runs since then, same path etc and GPS is working perfect. Exact same readings as Polar and Runkeeper.
So I put it down to bad GPS fix at the start of first ever run :p