4 ms·
If you know you have a single frequency close to an actual frequency of interest, you can use the fact you know you're in an aliased band to get a precise frequ
by hgomersall 5mo ago
If you know you have a single frequency close to an actual frequency of interest, you can use the fact you know you're in an aliased band to get a precise frequency estimate.
- jonathrg 5mo agoPresumably there is an antialiasing low pass filter somewhere before JS gets to the data. I have a similar sample rate and it certainly didn't work at all for me.
- ErroneousBosh 5mo agoIf the accelerometer samples at 50Hz, how could there be an antialiasing filter? What would that filter look like?
- colanderman 5mo agoAnything physical which dampens higher frequency oscillations would act as an antialiasing filter.
- ErroneousBosh 5mo agoWhat sort of size do you think something that would damp 25Hz vibrations in something that weighs a gram or two would need to be?
- regularfry 5mo agoThey have analogue AA filters just before the sampler.
- ckocagil 5mo agoaka a stroboscopic measurement, but I don't think it will work well for this case.
- KeplerBoy 5mo agoIt's just higher nyquist zones.
- superxpro12 5mo agoI guess thats sort of like a weird PLL thing? But I'd imagine you'd have to have prior knowledge of which string you're tuning otherwise the analysis is going to alias against every harmonic.
- regularfry 5mo agoEvery non-linear mixing of signals gives you sum and difference frequencies. It's less a weird PLL thing and more a weird trig function thing.
- kayson 5mo agoIts not even a non linear thing. Its a sampling thing. Even ideal sampling exhibits aliasing. https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampli...
- regularfry 5mo agoYes, and. You can look at aliasing as a special case of heterodyning. Sampling is a nonlinear mixing.