Yet Another Cycling Forum
General Category => The Knowledge => GPS => Topic started by: 321up on 24 January, 2014, 11:35:43 pm
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I'm looking for a way of getting more accurate altitude data for gps tracks recorded on my phone. I currently use Viewranger which records gps height data, but I don't think that it utilises the pressure sensor in the phone to filter out gps altitude errors (the way some Garmin units do). I've found the app "AndroSensor" which will record the GPS location and barometric pressure at intervals, so I hope to post process the data to create a gps track with more accurate height data. I've not tested it yet so I don't know if there is a limit to the recording duration or what impact it will have on battery life. Has anyone else tried this? Can anyone suggest a better Android app which uses GPS and the pressure sensor for recording tracks?
AndroSensor...
https://play.google.com/store/apps/details?id=com.fivasim.androsensor&hl=en (https://play.google.com/store/apps/details?id=com.fivasim.androsensor&hl=en)
Cheers.
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I recorded the GPS and pressure sensor data for our ride yesterday using AndroSensor. This is what I found thus far...
- the battery life did not seem unduly affected by running AndroSensor (compared with using Viewranger alone)
...post processing...
- I set an offset to align the GPS altitude data and pressure derrived altitude to the spot height at my start location.
- the pressure sensor derived altitude was fairly consistent with the GPS data for the first 30 minutes then was affected by a drop in atmospheric pressure
- I was able to correct for the atmospheric pressure drop by taking a long average of the GPS height data to create a correction factor
- the spot heights for the pressure derrived height on the top of main hills was within 7 metres of the map height as cross referenced with memory-map data.
Conclusion: The pressure sensor in my phone is capable of providing useful height data. The GPS data was thrown off when I took my phone into a cafe and my post processing algorithims require more work to correct for that scenario.