Suunto 9 FusedAlti not remembered after activity

surfboomerang

@Brad_Olwin what @silentvoyager is saying is that he sees the fused altitude working in the first graph within a few minutes. The first activity ends at an altitude of around 339m.

He starts the second activity 5 minutes later with an altitude of 258m. Such a huge difference can’t be from air pressure change in such a short time.

After a few minutes he sees the fused altitude working again because the altitude is corrected to 344m (almost identical as the end altitude of the first activity).

You would suspect that after the ending the first activity the altitude will stay at around 339m until he starts the second activity. If the second activity starts days after the first I can imagine the altitude has drifted off because of air pressure changes, bit not after 5 minutes.

@silentvoyager correct me if I understood your post wrong.

Brad_Olwin

@surfboomerang said in Suunto 9 FusedAlti not remembered after activity:

@Brad_Olwin what @silentvoyager is saying is that he sees the fused altitude working in the first graph within a few minutes. The first activity ends at an altitude of around 339m.

He starts the second activity 5 minutes later with an altitude of 258m. Such a huge difference can’t be from air pressure change in such a short time.

After a few minutes he sees the fused altitude working again because the altitude is corrected to 344m (almost identical as the end altitude of the first activity).

You would suspect that after the ending the first activity the altitude will stay at around 339m until he starts the second activity. If the second activity starts days after the first I can imagine the altitude has drifted off because of air pressure changes, bit not after 5 minutes.

@silentvoyager correct me if I understood your post wrong.

The first activity ends at about ~214 and the second starts very, very close to that once Fused Altitude has initiated…are you saying the second should start at 215? Mine tends to remember as I can check altitude.

Mff73

@Brad_Olwin
I think the first is your second and the second your first.
But maybe wrong.

A Former User

@Brad_Olwin The second one started 5 minutes after finishing the first one. The change in altitude between the two runs was insignificant. You can see a significant altitude adjustment at the beginning of the second run, which doesn’t make much sense to me.

A Former User

@Brad_Olwin, No 214 ft is where I started the first activity and where I returned to at the end of the second activity. Basically my run was interrupted because I met someone and stopped the run, but then decided to record the rest of it.

freeheeler

I’d like to roll up this ancient topic if I’m allowed to…
but with a somehow different basis of the question to you folks.
Did you ever notice that all your start altitudes that you start from a known point differ by several meters? My frequent starting alti is on 424m.
My activities sometimes show 404m on the graph up to 449m. But usually around 416m, hence 8m too low.

I know that FusedAlti kicks in after something like 15minutes but I remember that it changes the graph backwards in order to not only correct the altitude but also correct a potentially wrong start altitude, am I wrong?

What is your experience?

freeheeler

…and while I’m already asking…
I went for a short ride along the lake (which is supposed to be a flat track) and I went to a shop (5th floor) while I paused my activity and later I found the following on the alti graph recording… I’ve restarted the activity exactly where I’ve stopped it some minutes before.

Dimitrios Kanellopoulos

@TELE-HO temperature influence. That has not Todo with correction. If you stay inside it will get wrong gps altitude and temperature will be increasing or falling changing the altitude. That is why 20meters chnaged

Dimitrios Kanellopoulos

@TELE-HO fused alti does not work only in the first 15 minutes. This is chnages quite some time ago. It will try many times and additionally constantly correcting the altitude

surfboomerang

@TELE-HO I have never seen it correcting it from the start. Sometimes it takes 20-25 minutes to kick in and then I see the altitude gradually being corrected in the next few minutes.But the beginning of the activity still contains the wrong altitude.

Dimitrios Kanellopoulos

@surfboomerang you cannot see the correction of the altitude.

There is the initial offset adjustment that you don’t see and after that during ie if the pressure chnages and it does not align with the altitude then it will gradually correct it.

Note: -+10-20meters will be corrected slowly not fast during the activity not on offset.

Dimitrios Kanellopoulos

@TELE-HO in your specific example the correction happened when you existed the store most probably. Should not happen so much , and mostly it trusted the temperature.

The fused alti is not designed so well for indoor and floors etc when gps is on (no indoor activity)

Alternatively you could do multisport to indoor move and would help.

surfboomerang

@Dimitrios-Kanellopoulos
you mean this:

The track should be flat, but it is slowly corrected to (almost) the right altitude in the end.

freeheeler

@Dimitrios-Kanellopoulos
you mean it still wants to correct, even when paused?

Dimitrios Kanellopoulos

@surfboomerang yes but even if you had the altitude at start at 1000m the same chart could happen.

At start it would calibrate immediately to let’s say 10meters and slowly go to 0. So initial calibration error would be 10meters (just en example)

Also the flat at NL (I have sometimes same charts) is not always so flat (or everywhere).

For example my house is at -10 while at 5km I am at 0 (sea).

However this is going to be improved for those 10meter variations. That line will go correct much faster for flat runs.

10meters is very small error but it shows well if you do not live in a mountains area.

Dimitrios Kanellopoulos

@TELE-HO correct. Also in the prestart screen it will do it. Sometimes even if you just turn on the gps for 1min if it can.

Prestart is when you see the start and wait for the gps lock

freeheeler

@Dimitrios-Kanellopoulos said in Suunto 9 FusedAlti not remembered after activity:

temperature influence

this is temperature influence, alright. I’ve learned something new.
Then we also need to be aware of changes e.g. when we start a hike with a shirt in the cold and put on a warm jacket and gloves that heats up the watch body and sensor, right?

freeheeler

@Dimitrios-Kanellopoulos said in Suunto 9 FusedAlti not remembered after activity:

10meters is very small error but it shows well if you do not live in a mountains area

true! don’t get me wrong, I just want to understand and learn since I observed this behaviour

Dimitrios Kanellopoulos

@TELE-HO temperature will influence more when there is no pressure change or if you are “static”.

No it won’t influence asap.

You should not worry about it at all. It need sharp change.

However, if your sensor is dirty yes it will. Not because of the algo or the component but rather of the debris that will do a systolation or diastolation and move the component (sensor).

freeheeler

@Dimitrios-Kanellopoulos
interesting stuff and nice to know
in general: we shouldn’t worry too much.