General > General Technical Chat
FFT and 60 Notch filter software
gf:
Is the .wav file supposed to contain any useful information?
Besides the spurs, everything looks like random noise to me :-//
Karel:
--- Quote from: tggzzz on March 13, 2024, 11:56:41 am ---
--- Quote from: loop123 on March 13, 2024, 11:41:52 am ---Surface biopotentials of 10uV, 1000Hz. Experimenting on bionics implants. It will be difficult to "Design a PLL controlled VCO that creates the clock for your ADC chip and synchronize it with the powerline frequency.". Who has actually built them? can you guys just do it on existing software? are you saying no software can even filter them? but pls answer 2 messages prior what those noises are in the first place bec they seemed not to be harmonics owing to lack the resultant as shown in the figure.
--- End quote ---
For medical electronics, especially implants, it is essential that you use hardware designed for such purposes in a way specified by the manufacturer.
Any homebrew hardware or hardware operated in a system not designed for medical purposes may be a safety hazard. The tone of your repeated questions makes me doubt that you are qualified to design and/or operate such hardware. Hence be very careful of the consequences of your actions and inactions. Consult the terms and conditions of relevant professional insurance policies, looking to see whether you might be personally liable.
If the digitiser has adequate dynamic range (see the ENOB specification) and higher than necessary sampling rate, then downconverting to any lower rate is a standard DSP operation with well known consequence. Consult any DSP textbook, and use DSP software. Do not expect standard audio hardware and software to be sufficient.
Wrtng sntncs like this mks u lk unprofessional.
--- End quote ---
If the device is not advertized as a medical device, for example when it's intended use is for research only, you can do almost whatever you want
(prohibited the approval of an ethical commision).
As soon when it's going to be used for patient treatment and/or monitoring, you'll need to comply with EN/CEI 60601 and all the applicable/resulting other norms...
loop123:
--- Quote from: gf on March 13, 2024, 12:11:05 pm ---Is the .wav file supposed to contain any useful information?
Besides the spurs, everything looks like random noise to me :-//
--- End quote ---
It is just sine wave generator output of 10uV, 50Hz sine wave. Simple only but why is the output at Audacity has so much noise? Goal is simply to remove the noise and regain the pure 10uV, 50Hz sine wave. pls help do that.
Btw the amplifier is for use on mice so dont worry guys. see specs at
https://cwe-inc.com/products/bma-200-acdc-bioamplifier
gf:
--- Quote from: loop123 on March 13, 2024, 12:52:00 pm ---
--- Quote from: gf on March 13, 2024, 12:11:05 pm ---Is the .wav file supposed to contain any useful information?
Besides the spurs, everything looks like random noise to me :-//
--- End quote ---
It is just sine wave generator output of 10uV, 50Hz sine wave. Simple only but why is the output at Audacity has so much noise? Goal is simply to remove the noise and regain the pure 10uV, 50Hz sine wave. pls help do that.
--- End quote ---
My understanding was that the 50 Hz component (and the other spurs) are interfering signals which you want to suppress. If, OTOH, the 50 Hz signal is the useful signal you want to keep (while all the other spectral components should be suppressed), then this can easily be done with a narrow bandpass filter. However, I think this is not what you really want. A real EEG signal is not a pure 50 Hz sine wave, therefore such a bandpass filter would suppress most of the useful components in a real EEG signal. Is the EEG simulator not able to simulate a more realistic EEG signal?
Karel:
I opened your wav file in EDFbrowser and it doesn't look noisy.
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