ÉN
Subject: Ascent - average
Message: I would like to completely understand how exactly "ascent -average" is calculated. For instance is there any minimum threshold of ascent like ascending more than 2 or 3 meters before the logged data is considered as an ascending section? How the elevation data are filtered and/or smoothed before adding a new datum to those used for "ascent -average" etc. Thanks
ŐK
Thank you for contacting Garmin International. I would be happy to assist you with this. Even when the unit is lying still, it is constantly receiving signals from satellites and continuously calculating a position. In doing so, the unit is adding together the fluctuations in GPS altitude which, is how the total ascent is calculated. Please let me know if you have any further questions.
ÉN
My original question was different. Could you please check it and send me an answer? It is regarded the metric called 'ascent-average' and 'total ascent'. My question focuses on whether there is any smoothing behind 'ascent - average', because my experience of many years is that as regards 'total ascent' there is some kind of smoothing. Thanks
ŐK
Thank you for contacting Garmin Europe. In regards to your question. The total ascent is the total vertical distance climbed over the duration of your current activity. the Average ascent calculates your current rate of ascent in feet/metres per minute as this is an average, then there will be a degree of smoothing to this.
Using the autocalibration feature on the device, the accuracy is +/- 50-125ft (same as GPS elevation). When manually calibrating (autocalibration off) to a known elevation it is approximately +/- 10ft for the first 15 minutes. The unit should be calibrated hourly to maintain accuracy when using manual calibration because of possible pressure changes.
If using a locally reported pressure reading to calibrate the device, the accuracy of the altimeter would depend on the time and location of the reading.
With WAAS and good reception you can obtain an accuracy of +/- 25-50ft. The barometric pressure sensor, which is responsible for altimeter readings, is not temperature compensated. Temperature changes in the measuring device will affect the barometric pressure sensor and altimeter readings, but these readings will remain within the stated accuracy for the device: approximately 10 feet with proper calibration by the user and slightly higher when using automatic GPS calibration. Please let me know if you have any further questions.
ÉN
Thanks for the longer answer, finally I will perhaps get the answer I need. So far I found out that there is a smoothing in case of average ascent as I had assumed it. But actually my question was NOT about any accuracy. My inquiry was about the details of the smoothing and filtering, about the exact algorithm:
"I would like to completely understand how exactly 'ascent - average' is calculated. For instance is there any minimum threshold of ascent like ascending more than 2 or 3 meters before the logged data is considered as an ascending section? How the elevation data are filtered and/or smoothed before adding a new datum to those used for 'ascent - average' "
Let me be clear without offence meant: does Garmin deliberately hide these pieces of information due to any reasons or is my English poor to express that I really wish to find out the exact smoothing and filtering algorithm?
Thanks
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