Live Pace Accuracy

8601751 said:

Running software 17.26

Here is the problem. I noticed too that "instant pace" is not really instant but rounded average with about 20-30 sec base. Sad but the truth - Garmin does it again - i don't no what is happens now - new version of GNSS chipset SDK is out and only one intern has time to compile a new version without correction all default variables, or-or-or... They comes all the next week back from holidays and and may be corrects all the bugs. 

The 17.xx updates broke instant pace for me.

Previously it used to work on what i guess was a 5 second or so average (and rounded to 5 sec bands on display) so worked nicely for intervals and adaptation on a run.

Now it "feels" to make like its more of a 30 second rolling average and giving me nothing instant to adjust to.  Theres so much averaging time on the latest update i really cant use it for anything at all.  Run up a hill, get to the top, speed up and watch your pace decrease for a good while etc.

The issue for me is instead of maybe 5 seconds average which allowed instant adjustment its now 20-30 seconds so so delayed its impossible to use it as a reference.  That isnt the GNSS/Chipset as it all worked fine until the 17.x updates a month or two ago.  Theyve made a software change, either deliberate or accidental that broke a useful feature.

I'm new to Garmin (purchased 255m in early Nov 2023) and have picked up that the "instant" page is a moving average. I'm not surprised by the 20 to 30s window estimate being cited here based on my experience.  I wish it were shorter, but maybe there's a technical reason that it has to be that large a window. 

What's most frustrating is that each lap (auto or manual) seems to throw the instant pace calculation off.  Like the watch forgets what was happening the end of the prior lap and starts over with the calculation of the instant pace.  I regularly get pace alarms at the beginning of each lap until it gets back in the zone.  If I'm doing a lot of fairly short repeats, that behavior means it's off throughout the entire run..

I'm learning to ignore things and just keep focused on the physical feel of the pace. Still, it's frustrating to have to take that attitude toward a basic feature of a running watch.

Hi there,

I think that "instant" pace never is instant. I may be wrong, but I do not know any watch from any brand that implements "instant" pace that is not a moving average or use some kind of smoothing. It is just a technical limitation derived from GPS accuracy limitations.

I find the 255 pace to be more reliable than my previous 745 (the new GPS chip is better), which it was better than my previous 645. But it still can be very inaccurate depending on GPS reception.

In cities with tall buildings, just forget to get a reliable pace from any watch. The fastest you move, the smallest the errors you get when calculating speed. For most of us that run between 10kph to 20kph it's just not fast enough... If you are on a bike at 40kph, it won't be perfect, but at least twice more precise, and so on.

If anyone knows of any watch from any brand that is able to get pace right at 12kph, just let me know... IMHO technology is not yet there, but it is improving (very) slowly over time.

   Best,
   Kurt.-

It is a bit strange. When looking at the data feed from GPS antennas, speed is usually the most accurate data (except for time). Altitude is always far out, and horizontal location can be off if the reception is not so good. But speed (derived by doppler) is usually spot on. I think faster data would be nice even if it is not completely accurate. 

I am not an expert in the field. I see that Doppler-aided speed calculations from GPS signals (something that I did not know about)  exists for at least more than 10 years (I am finding articles from 2011), so it's an easy guess that every vendor is using that for at least 5 or 6 years (or even more). Why wouldn't they? Probably that calculation is embedded in the GPS chip, but I am speculating here.

I don't know how accurate it is or it isn't, but I know that I have not seen any watch that does not exhibit problems with pace. Sometimes it is good, even very good... but sometimes it is off (even very off). I've seen that in every watch I've had, and I've had many over the years. 255 is the best I've had in that regard to this moment.

Let me know a watch that shows a reliable pace all the time even in cities, and you will  make me happy (and my wallet will be lighter)

   Best,
   Kurt.-

kurtie_bcn said:

Let me know a watch that shows a reliable pace

Hi there!

my 5 yo vivoactive 3 with old sony chipset gives me instant pace*. on the right hand if fr255 is on the left. Same conditions, same weather, buildings (none at all) etc. 

The same fr255m gave me instant pace* bevor last update.

*) - instant pace is the rolling (moving) pace with a short time base - normally it is 3-5 sec. short. Then you see your acceleration in real time and not 10-15 sec later as we have it now. 

Hi,

   I have had at least one watch with that GPS chip (745 or maybe the 645, maybe both), and where I run it was not rare to see pace swinging a lot (more than one minute per kilometer above or below expected pace) 645 performed very poorly, 745 was better, 255 is better in my experience, yet far from perfect. YMMV, GPS reception is not the same everywhere and everytime.

   I think the complaint here is the size of the "smoothing window". The thing is: the shortest the smoothing window, the wildest the results can be when GPS recepction is not good enough.

   Maybe one solution would be to make that configurable, so that we can choose the size of that "smoothing window". Some people may prefer a more reactive pace even if it does mean some wild spikes in it, or maybe because they execise in areas with very good GPS reception, they will get good pace with smaller smoothing. While others may prefer a more reliable pace even it it does mean a less reactive pace.

   Best,
   Kurt.-

It could be different data fields. Live pace should be quick but not necessarily accurate. This is what you need for short intervals and sprints. Filtered pace could be more accurate with more lag, which is more useful for long distance running. You could have both in the same view if you want.