Advanced Grade is an app that eliminates grade (slope) jumps in Garmin Edge devices. It has many settings for flexible custom setup of the filtering of the grade. In addition it can display the max/min elevation and max/min pressure. All of the selected variables can be displayed with one decimal place. The default settings are chosen to ensure a balance between accuracy and fast response.
In stage 1 the raw grade is calculated from the "Grade source" and the elapsed "Distance", then it's rejected if it's higher than the maximum allowable value. The remaining raw grade is filtered and if it deviates from its filtered value by more than the parameter "Max deviation", it's rejected. In stage 2, the remaining raw grade from stage 1 is filtered. So, for the lag, first you have to ride "Distance" metres for the raw grade calculation, then you need "Settling time" seconds for the filtering in stage 2. Additional "Settling time" seconds for the filtering in stage 1 is needed only at first start, or when the change in the grade is more than the max deviation for long time. For example: you ride +12 degrees uphill and after the grade is stabilized around this value, then immediately -12 degrees downhill for more than the sum of the settling times from both stages.
Configuration screens on Garmin Express:
Features:
Label
- the title of the datafield, maximum 20 characters.
Decimal point
- when switched on, the selected variables are displayed with one decimal place.
Separator
- the separator between the selected variables.
Reset on Lap
- what to reset, when "Lap" button is pressed.
- default value is "Max/min grade".
Max/min set time (s) [1 - 20]
- max/min values settling time.
- default value is 3s.
Grade (%)
- display the output grade from stage 2.
Maximum grade (%)
- display the maximum of the output grade from stage 2.
Minimum grade (%)
- display the minimum of the output grade from stage 2.
Elevation (m)
- display the altitude above mean sea level.
Max elevation (m)
- display the maximum altitude.
Min elevation (m)
- display the minimum altitude.
Pressure (hPa)
- display the ambient (local) barometric pressure, it's smoothed by a two-stage filter.
Max pressure (hPa)
- display the maximum pressure.
Min pressure (hPa)
- display the minimum pressure.
Stage 1 - Calculating the grade and rejecting its false values
Grade source
- grade calculation source, it can be "Pressure", "Altitude" or either of the two whose output is smaller in absolute value "Min (Press, Alti)".
- default value is "Pressure".
Distance (m) [1 - 100]
- traveled distance, based on which the grade is calculated.
- default value is 20m, my advise is to not set it below 10m.
Max limit (%) [1 - 100]
- if the grade is higher than this value, it's rejected
- default value is 30%, you can change it depending on the maximum grade you will be climbing.
Max deviation (%) [1.0 - 20.0]
- if the grade deviates from its filtered value by more than this parameter, it's rejected.
- default value is 4.0%, my advise is to not set it below 2.0%.
Filtering mode
- this filter is used in combination with "Max deviation" to reject the false values of the grade.
- moving average and 2-nd order Bessel filters are applied to the signal, the one whose output is smaller in absolute value is chosen.
- default value is "Min (MA, Bessel)".
Settling time (s) [1 - 20]
- the settling time of the filters.
- default value is 4s, my advise is to not set it below 4s.
Stage 2 - Filtering the remaining grade values from stage 1
Filtering mode
- moving average and 2-nd order Bessel filters are applied to the signal, the one whose output is smaller in absolute value is chosen.
- default value is "Min (MA, Bessel)".
Settling time (s) [1 - 20]
- the settling time of the filters.
- default value is 8s, my advise is to not set it below 4s.
Debug - Write to FIT
- the selected grade values will be written to the FIT file: S1 input (%), S1 output (%), S2 output (%) are represented as s1_inp s*, s1_out d*t*, s2_out t* respectively, where s* is the grade source, d* is the max deviation and both t* are the settling times of the filters in stage 1 and 2 respectively.
S1 input (%)
- write the input grade of stage 1.
S1 output (%)
- write the output grade from stage 1.
S2 output (%)
- write the output grade from stage 2.
Changelog:
Version 1.7
In stage 1 is added option for grade calculation source.
In the debug section, the grade values can be written to the FIT file.
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Version 1.6
Fixed issue with elevation not showing in some cases.
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Version 1.5
Added settling time for max/min values.
Added new filter, which is combination of moving average and 2-nd order Bessel.
In the debug section is added option to save grade values in the FIT file.
Raw pressure is removed from the debug section.
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Version 1.4
The three stages are combined into two.
The filtering algorithm is changed to exponential moving average.
The default settling time of the filter in stage 1 is decreased to 4s.
Some parameter names and ranges are changed.
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Version 1.3
The history buffer for calculation of the raw grade is increased.
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Version 1.2
Now max/min elevation is calculated only during activity.
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Version 1.1 is the first official release.
