11–20 of 93 posts
Wouldn't it be far easier to just transmit a wifi SSID that encodes this information?
Is it really ultrasound? Microphones on phones may be able to pick this but what speakers are able to play even 20 kHz? And these apps should always listen, that will drain battery quickly, so these apps will be listed in top power-consuming apps and user will notice it.
18-19 kHz is usually high enough; smartphone speakers can play that fine from my experience. Yes, battery drain is an issue. Most apps use a background service that wakes up at a fixed interval. The longer the interval, the longer the broadcast has to be though, so it's basically a trial and error kind of thing.
Sounds a little like one of Powa Technologies ideas before they went boom. Embed inaudible tones in tv content to sell you stuff. Never saw the appeal. But as we know the appetite for tracking is endless, foe some reason.
Earlier quoted context omitted.
18-19 kHz is usually high enough; smartphone speakers can play that fine from my experience. Yes, battery drain is an issue. Most apps use a background service that wakes up at a fixed interval. The longer the interval, the longer the broadcast has to be though, so it's basically a trial and error kind of thing.
Another issue (besides the privacy issue) is that it may be annoying for pets. Dogs and cats can hear these sounds. Also the apps on the phone have access to the microphone (even though they probably do not need this permission for any other purpose), so these apps are all potential listening devices.
This is why apps that shouldn't need the mic or speaker but still require it should not be installed. Permissions on an app should be checked carefully by a user, and users should be educated in this!
Having the app ask on first use makes much more sense. It's much less likely to get away with this. Even better, you can still use the app if you say no. It will just get dummy values back.
Would that even work? I'm pretty sure modern digital TV audio compression totally removes sound that is vaguely close to 'ultrasound'. I guess maybe smart TV apps could add the signal though, but why would they when they already know what you are watching?
It reminds me of a website for one of those annoying 'Mosquito' anti-loitering devices. The sound was provided as an MP3, which was of course totally filtered out by the compression resulting in a totally empty file.
Is there a physical way to deactivate the microphone (on my tablet, I never use it)?