From the file, can you tell if the noise is external or in the circuit??Are you only measuring one channel/electrode, or multiple channels/electrodes? Your photo only shows one waveform, so I'm assuming you're only measuring a single channel/electrode.
If you measure multiple electrodes, you can mathematically remove the common noise. The theory is that the skin potentials will be different at each electrode, but the noise (particularly 60Hz and other EMI) will be the same in all channels.
EEGlab can do this multiple channel common noise reduction, and I'm pretty sure Audacity should be able to do it with two channel stereo. The key is that you need multiple channels, not single.
From the file, can you tell if the noise is external or in the circuit??Are you only measuring one channel/electrode, or multiple channels/electrodes? Your photo only shows one waveform, so I'm assuming you're only measuring a single channel/electrode.
If you measure multiple electrodes, you can mathematically remove the common noise. The theory is that the skin potentials will be different at each electrode, but the noise (particularly 60Hz and other EMI) will be the same in all channels.
EEGlab can do this multiple channel common noise reduction, and I'm pretty sure Audacity should be able to do it with two channel stereo. The key is that you need multiple channels, not single.I used single electrode pair connected to the Netech EEG simulator as shown in photo.
Your description about using multiples samples is a separate task.
From the file, can you tell if the noise is external or in the circuit??Are you only measuring one channel/electrode, or multiple channels/electrodes? Your photo only shows one waveform, so I'm assuming you're only measuring a single channel/electrode.
If you measure multiple electrodes, you can mathematically remove the common noise. The theory is that the skin potentials will be different at each electrode, but the noise (particularly 60Hz and other EMI) will be the same in all channels.
EEGlab can do this multiple channel common noise reduction, and I'm pretty sure Audacity should be able to do it with two channel stereo. The key is that you need multiple channels, not single.I used single electrode pair connected to the Netech EEG simulator as shown in photo.
Your description about using multiples samples is a separate task.
It's actually not a separate task, all the channels can be done all together. Noise removal is performed on all channels simultaneously, not individual channel one-by-one.
What I want to determine for now is whether the noise is caused by EMI or the amplifier not capable of 10uV as Ataranov remarked. Bec even if I spent $3000 on human size Faraday cage. The distortion would still be there if it is the amplifier that has problem. If thats the case, then have to dive and spent $5000 on USBamp software and actives if it is the only means of last resort. So how do you know if the distortion is really caused by EMI or the amplifier just not capable of handling 10uV even if the amp used is the 5nV/sqrt(Hz) noised AMP01?
I just want to know the frequencies involved in the distortions for now and not about eliminating them right away.
Or he could look at p374 in https://www.worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1974-10.pdf and find an article "Mains Rejection Tracking Filter - using a tracking 'n-path' filter with wide dynamic range" to remove not only the fundamental but also the harmonics.
Not many people understand weird and wonderful n-path filters. I expect it would blow the OP's mind.
Or he could look at p374 in https://www.worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1974-10.pdf and find an article "Mains Rejection Tracking Filter - using a tracking 'n-path' filter with wide dynamic range" to remove not only the fundamental but also the harmonics.
Not many people understand weird and wonderful n-path filters. I expect it would blow the OP's mind.I completely forgot about that concept. Yes, done right, you can eliminate the mains interference completely. However, if loop123 is using his amp to read human biometrics, you have the problem that every time you re-wire to a new person in a different place, you may too radically change your source interference characteristics.
If loop123 has enough input channels, just sacrifice 1 channel as you mains reference noise channel. Then, subtract that channel's signal from all your channels of interest and you will null out your main's noise.
It's basically how a differential line signal works.
Oh man, that 6.7khz tone in the .wav is maddening. And I see a main dominant 50hz spike. There was a weaker 60hz and 80hz tones as well. Are you sure this was recorded in north America? Or, did you attempt some sort of filter algorithm which injected some fundamentals?
Synchronize the sampleclock of the ADC to the powerlinefrequency e.g. using a PLL.
That makes it way easier to remove the powerline interference (including harrmonics).
https://www.mainsfrequency.com/
Synchronize the sampleclock of the ADC to the powerlinefrequency e.g. using a PLL.
That makes it way easier to remove the powerline interference (including harrmonics).
https://www.mainsfrequency.com/
I talked to the designer of E1DA. Ivan said:
(Attachment Link)
Well. Ivan is a Russian electronics wizard. If he could say that. How can I even counter it. Ok. Someone please give an actual example how to filter the waveforms in the file I sent 2 messages prior. Please do it directly using your Apps, then I'll filter hundreds of other inputs myself after you actually showed the filter output by actually running it in your software. Thanks.
Synchronize the sampleclock of the ADC to the powerlinefrequency e.g. using a PLL.
That makes it way easier to remove the powerline interference (including harrmonics).
https://www.mainsfrequency.com/
I talked to the designer of E1DA. Ivan said:
(Attachment Link)
Well. Ivan is a Russian electronics wizard. If he could say that. How can I even counter it. Ok. Someone please give an actual example how to filter the waveforms in the file I sent 2 messages prior. Please do it directly using your Apps, then I'll filter hundreds of other inputs myself after you actually showed the filter output by actually running it in your software. Thanks.
That's because your samplerate is not an integer multiple of the powerline frequency.
I thought we were talking about EEG and/or EKG here and you could select the samplerate.
If your application is about recording audio, then it's much easier to get rid of powerline interference (compared to EEG/EKG)
but you need to pay attention to grounding.
Synchronize the sampleclock of the ADC to the powerlinefrequency e.g. using a PLL.
That makes it way easier to remove the powerline interference (including harrmonics).
https://www.mainsfrequency.com/
I talked to the designer of E1DA. Ivan said:
(Attachment Link)
Well. Ivan is a Russian electronics wizard. If he could say that. How can I even counter it. Ok. Someone please give an actual example how to filter the waveforms in the file I sent 2 messages prior. Please do it directly using your Apps, then I'll filter hundreds of other inputs myself after you actually showed the filter output by actually running it in your software. Thanks.
That's because your samplerate is not an integer multiple of the powerline frequency.
I thought we were talking about EEG and/or EKG here and you could select the samplerate.
If your application is about recording audio, then it's much easier to get rid of powerline interference (compared to EEG/EKG)
but you need to pay attention to grounding.
My amplifier target input is 10uV, 1000Hz with gain of 50000. The output bandwidth is set at 1000Hz. So the output is 10uVx50000= 0.5V, 1000Hz. The ADC is to record the 0.5V, 1000Hz. What samplerate must I adjust in Audacity so I can filter the powerline frequency and harmonics?
First, please tell me what exactly are these noises? In the 2nd image, they don't look like harmonics:
If they are harmonics. They should be resultant in the waveform. But my audacity waveforms don't show any resultant. The noises are riding in each part of the sine wave. How do you differentiate between EMI, RFI, amplifier noise, and quantization ADC noises? How sure are you they are powerline noises or harmonics? Please tell me what exactly those are first.
Synchronize the sampleclock of the ADC to the powerlinefrequency e.g. using a PLL.
That makes it way easier to remove the powerline interference (including harrmonics).
https://www.mainsfrequency.com/
I talked to the designer of E1DA. Ivan said:
(Attachment Link)
Well. Ivan is a Russian electronics wizard. If he could say that. How can I even counter it. Ok. Someone please give an actual example how to filter the waveforms in the file I sent 2 messages prior. Please do it directly using your Apps, then I'll filter hundreds of other inputs myself after you actually showed the filter output by actually running it in your software. Thanks.
That's because your samplerate is not an integer multiple of the powerline frequency.
I thought we were talking about EEG and/or EKG here and you could select the samplerate.
If your application is about recording audio, then it's much easier to get rid of powerline interference (compared to EEG/EKG)
but you need to pay attention to grounding.
My amplifier target input is 10uV, 1000Hz with gain of 50000. The output bandwidth is set at 1000Hz. So the output is 10uVx50000= 0.5V, 1000Hz. The ADC is to record the 0.5V, 1000Hz. What samplerate must I adjust in Audacity so I can filter the powerline frequency and harmonics?
Change the recording samplerate of your device from 44.1 KHz to 48 KHz which is an integer multiple of 60 (and 50) Hz.
Design a PLL controlled VCO that creates the clock for your ADC chip and synchronize it with the powerline frequency.
That gives you much more options to use sophisticated algorithms in order to remove the powerline interference.
But we can help you better if you tell us what you want to achieve. What is it what you want to measure? Audio? Something else?
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.
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.
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.
Is the .wav file supposed to contain any useful information?
Besides the spurs, everything looks like random noise to me
Is the .wav file supposed to contain any useful information?
Besides the spurs, everything looks like random noise to meIt 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.