Calculated Fields

by camel

Downloads: 23,629 (9) • Reviews: 4

Version:

1.2.9.4

Updated:

Apr 11, 2011

Time Discrepancy

Time Discrepancy

Postby RogerRab » Mon Apr 27, 2015 10:00 am

I am trying to create an index that use times in a hr zone.
My focus is Zone 4 of the HRR (custom) hr category.
After checking that HRR Zone 4 is 150 to 162, I try 2 different ways to pull this data:

1) An Elapsed Time custom field with the formula: {RANGEELAPSED(HR,150,162)} This gives me: 10:40
2) A Sum custom field with the formula: {DATATRACK}.Where(o => o.HR >=150 && o.HR <= 162).Count() This gives me: 640 (the same amount as above displayed in seconds.)

Yet, when I look at "Daily Activity" for HRR Zone 4: I see "11:05".

Can anyone clue me in on the reason for the difference?
RogerRab
 
Posts: 5
Joined: Mon Apr 27, 2015 9:47 am

Re: Time Discrepancy

Postby tndmbkr » Mon Apr 27, 2015 11:55 am

CalculatedFields and CalculatedCustomDataTrack are insensitive to the smoothing factor
But the calculation by ST core is VERY sensitive to the smoothing factor.
Though that should change the time discrepancy in another direction.

Some other reasons:
My Garmin device starts counting seconds the moment I start the device. But measurements only start when the device thinks it has an accurate GPS signal.
Did you split your activity ? Did you include stopped in time and distance totals ?
Did you turn off your Garmin some time after you stopped your device?
tndmbkr
 
Posts: 233
Joined: Wed Jan 11, 2012 2:39 am
Location: Rotterdam

Re: Time Discrepancy

Postby RogerRab » Mon Apr 27, 2015 1:21 pm

Thanks for the explanation. In response to your questions:

The GPS is always locked before I start my run
The activities are never split
There are no pauses or stops in the exercise.

The other interesting thing is that the discrepancy between ST3 and Calculated Fields shrink as the HR range grows.
RogerRab
 
Posts: 5
Joined: Mon Apr 27, 2015 9:47 am

Re: Time Discrepancy

Postby tndmbkr » Mon Apr 27, 2015 4:23 pm

I spent some time to figure out the exact limits of the HRzones in ST.

In CalculatedCustomDataTracks you can define your zones very clearly.
The HRzone includes HR=135 or not.
When you create a HRzone in ST from 135 to 145, then 135 is part of that HRzone, and 145 is part of the next HRzone ?

Changing the HRzone with 1 bpm makes a lot of difference for the time spent in each zone.
Changes in the range of 7% are not unusual.
Somehow ST finds 600 HRvalues from 135 to 136 in an activity with 4800 HRvalues from 120 to 135
Likewise for the plugins CDT and ClcFlds
Which is not very plausible to me.


I created three calculated custom data tracks to calculate the percent of time I spent in three HRzones
HRzoneD1: 120-135 (135 not included)
HRzoneD2: 135-145 (135 included, 145 not included)
HRzoneD3: 145-155 (145 included)

HRzoneD1 = 1 when HR=120-135 (135 not included)
HRzoneD1 = 0 when HR>=135
etc

I also created HRzones in ST
D1 from 120 to 135 (120 included 135 not included ?)
D2 from 135 to 145
D3 from 145 to 155

In the chart below (CDT plugin) you can see HR values (standard track) and the rectangles for the values of HRzoneD1 etc
In the HR Zone Table I selected D3. The corresponding areas in the chart are dark colored red.
One would expect the selected HR Zone to overlap the rectangle for HRzoneD3.
But that does not happen.
Because of data smoothing.
The HRtrack is smoothed over 6 sec
Image
The leftmost selection of D3values starts exactly where HRzoneD3 starts.
But on the right side it is smaller than the rectangle for HRzoneD3
The second selection of D3values starts exactly where HRzoneD3 starts
But on the right it is larger than the rectangle for HRzoneD3
The third selection of D3values starts before the rectangle of HRzoneD3values.
But ends together with the rectangle of HRzoneD3
tndmbkr
 
Posts: 233
Joined: Wed Jan 11, 2012 2:39 am
Location: Rotterdam


Return to Calculated Fields

Who is online

Users browsing this forum: No registered users and 1 guest

cron