41–50 of 105 posts
Earlier quoted context omitted.
Ah, that does look like something I can work with - thanks for the legwork, I will check it out and see if its worthwhile converting to C/C++ for my device ..
That was for a microphone based version. This is the accelerometer one https://github.com/tautme/phone-sensors/blob/main/accel-tune...
This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.
Anyone got a handle on the algorithm required to do this? I've got a pocketable accelerometer-enabled device I'd like to try to implement this on..
Don't have a handle on it, unfortunately. But the algorithm is in here: https://github.com/tautme/phone-sensors/blob/main/guitar-tun... . Esp. lines 221–257 and 373–417.
Not a very good method, prone to octave errors (showing pitch one octave lower than the correct one). Furthermore, the "delay" is an integer which limits the precision, so you need to use some form of interpolation. Also it doesn't allow to recognize multiple notes sounding together. Also, slow.
You can read the paper on the "YIN" pitch estimation algorithm which describes the method in details.
I think FFT-based methods are more reliable. I did little experimentation and when measuring a pure sine wave, the frequency can be determined with high precision (tenths-hundredths of a Herz). Not so good in presence of a noise or multiple instruments - I tried to use descending from the hill optimization to figure out the pitch of each harmonic, but it didn't work out.
My accelerometer apparently reads at 200Hz, but due to a lack of instrument at the ready I had to "pluck" the handle of the office fußball table. When the right defender is near the center I'm reading ~24.74Hz, so slightly above G.
guitar detuner that uses accelerometer instead of microphone, it doesn't really work, but amazing to see how sensitive they are.
This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.
It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.
This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.
My accelerometer apparently reads at 200Hz, but due to a lack of instrument at the ready I had to "pluck" the handle of the office fußball table. When the right defender is near the center I'm reading ~24.74Hz, so slightly above G.
Earlier quoted context omitted.
It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.
The CIA…plug a set of regular headphones into a microphone jack, open a recording application and speak into the headphone speaker, you don’t need a 3 letter agency for that physics open secret.
My accelerometer apparently reads at 200Hz, but due to a lack of instrument at the ready I had to "pluck" the handle of the office fußball table. When the right defender is near the center I'm reading ~24.74Hz, so slightly above G.
heh, a subacoustic G#?