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Edge 520 Plus: Smart data recording not so smart

Today I did a ride and at the top of the climb I stopped to help a guy with his bike, the device kept recording data for about 40 min, saving data every second. I have disabled auto pause and auto sleep was on but the device never entered into sleep. The bike (and the device) was on an open space with clear view of the sky).

I read in the manual that smart data recording records a point when any of the field changes, I would expect that the "algorithm" they use would consider the possibility of noise or sensor drift/error but it seems it doesn't or even better, only save when the change in speed, distance, bearing, etc is over a predefined threshold (maybe user setteable).

Is there something I can do to prevent saving useless data? (without using auto pause)

I have attached a spreadsheet with the data saved during this period.

Also, anybody know what is the data in columns with label "Value 7" and "Value 8"?, they correspond to Field Def 61 and 66 of Fit protocol and are not documented in the SDK.2019-08-18-12-08-35.xlsx

0 tigermountrider over 4 years ago

Smart data was never intended to do what you expect. Its purpose is to reduce the number of data points recorded without affecting the accuracy of the data. Without auto-pause enabled it will continue to record when you are stopped. Its record rate is less than once a second but still frequent enough to accurately record what is happening even if that is not moving. If there is a power meter the recording is once a second regardless of the Smart recording setting. If you don't want to record when stopped that is what auto-pause is for.

0 fabian over 4 years ago in reply to tigermountrider

How much accuracy or information I gained by recording every second for 40 min while stopped?

0 cleansoap over 4 years ago in reply to fabian

> How much accuracy or information I gained by recording every second for 40 min while stopped?

You literally disabled auto-pause. IOW you told the Garmin you had value for data while stopped.

But on the "smart recording" side of the coin I do see lots of records where the only apparent change is ambient pressure, and this IMHO should not every trigger a record on its own. You have plenty of records where the delta distance is 0 and the speed is zero and the delta elevation is zero.

0 fabian over 4 years ago in reply to cleansoap

It was because a custom data field, it passed the ambient pressure to the fit recorder every second and the fit recorder doesn't know what to consider as a change for custom fields.