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This snippet (from the PDF) reveals the effectiveness of the technique: "To evaluate the first algorithm for distinguishing routes we recorded reference profil
by jawns 12y ago
This snippet (from the PDF) reveals the effectiveness of the technique:
"To evaluate the first algorithm for distinguishing routes we recorded reference profiles for several different routes. We used a dataset of 43 profiles for 4 different routes about
19 kilometers each. Driving in different directions along the same roads (from point A to B vs. from point B to A) is considered two different routes. We perform a leave-one-out
cross validation, each time using one of the profiles for testing. Figure 5 is a confusion matrix, which shows a high success rate in classifying the routes. The achieved successful classification rate in this case was 93%."
So, given a bunch of known routes (like a stretch of highway), this algorithm is able to match your phone's battery-usage signature to one of those routes, sort of like how a service like SoundHound is able to identify a piece of music based off of a few seconds' recording.
- ttty 12y agoBut that if the battery discharges exactly the same. I think that is not the case, for example the battery when is at 50% might discharge (doing the exact thing) differently than when is at 20%. Maybe the battery is not well calibrated or the internal part of the battery are more wasted than others.
- jahnu 12y agoI would guess that even if the curve is different from say 50% to 40% than 20% to 10% for the same journey it would be easy enough to normalise the data after profiling a couple of phones.
- ttty 12y agoPlus continuous change, but not even, would not be that easy.
- lione 12y agoWell since they have access to the battery info, they prolly take that into account.
- joenathan 12y agoAdditionally batteries degrade over their lifetime and will lose charge faster, also different phones have different wireless radios and different antenna configurations which would mean some phones would use more or less battery for the same operations.