pulse oximeter 'SPO2' / cut frequency

Thread Starter

razineabdelhak

Joined Aug 16, 2022
6
hello, hope every one is doing great, i created a pulse oximeter sensor, to get the right information from the sensor, i have to make a filter, from my resources, i found that the cut frequency is between the 0.7Hz and 2.34Hz, but on mu oscilloscope, I found it between 0.7Hz and 15Hz
My project is to create a pulse oximeter to calculate the oxygen saturation, heart rate
my question is
where is the right frequency area ?
thank you for helping me in advance :D
 

Papabravo

Joined Feb 24, 2006
19,330
hello, hope every one is doing great, i created a pulse oximeter sensor, to get the right information from the sensor, i have to make a filter, from my resources, i found that the cut frequency is between the 0.7Hz and 2.34Hz, but on mu oscilloscope, I found it between 0.7Hz and 15Hz
My project is to create a pulse oximeter to calculate the oxygen saturation, heart rate
my question is
where is the right frequency area ?
thank you for helping me in advance :D
What kind of resources do you have and what kind of filter did you have in mind?
 

Papabravo

Joined Feb 24, 2006
19,330
OK, so you already have a design for the filter from the article, but now you are wondering if that filter design is appropriate for the sensor, you actually built. Is that correct?

If that is the case, we can simulate the designs from the article to confirm that their performance conforms to the stated values. then if we need something else, we can tweak the values to be something else.

I'm confused about why you are asking for two different filter types. I know what a 2nd order Butterworth looks like, but is the "tow" filter actually a Tow Thomas Biquad? I'm just trying to make sure I understand what you are asking.
 

Papabravo

Joined Feb 24, 2006
19,330
yes, it is
Can you see how repeating your previous post makes no sense? Don't do that. I think you need to choose which of the two types of filter you want. You can have either a Butterworth or a Tow Thomas Biquad. You can't have both.

EDIT: Another problem is that the reference designators for the components in Table 2-1 don't match the schematic. You're going to have to be a great deal more specific about what you want if you expect any meaningful help.
 
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Thread Starter

razineabdelhak

Joined Aug 16, 2022
6
OK, so you already have a design for the filter from the article, but now you are wondering if that filter design is appropriate for the sensor, you actually built. Is that correct?

If that is the case, we can simulate the designs from the article to confirm that their performance conforms to the stated values. then if we need something else, we can tweak the values to be something else.

I'm confused about why you are asking for two different filter types. I know what a 2nd order Butterworth looks like, but is the "tow" filter actually a Tow Thomas Biquad? I'm just trying to make sure I understand what you are asking.
the tow filter types are created to avoid the frequency from ]0,0.7[ ]0.7,15[ so we need tow type of filter
about the simulation, the 2nd order Butterworth was my design, the circuit in article was a 1st order
my question was to know the exact area of the pulse oximeter, is between 0.7Hz and 2.34Hz as mentioned in the article or 0.7Hz / 15Hz as I've seen it on the oscilloscope ?
thank you again for your response :D
 

Ya’akov

Joined Jan 27, 2019
6,616
Yes, it is !
OK. The AAC rules for assisting with schoolwork are very specific. Members are not allowed to help beyond working with you on the specific solution you come up with. This thread has been moved to the Homework Help forum to let members know that's what they are dealing with.

Welcome to AAC. We love to help with schoolwork but we have to follow our rules, they are for your benefit. Please continue but remember you have to "show your work", that is, you have to explain what you have tried, or what you think the specific soli
 

Thread Starter

razineabdelhak

Joined Aug 16, 2022
6
Yes, i know that
OK. The AAC rules for assisting with schoolwork are very specific. Members are not allowed to help beyond working with you on the specific solution you come up with. This thread has been moved to the Homework Help forum to let members know that's what they are dealing with.

Welcome to AAC. We love to help with schoolwork but we have to follow our rules, they are for your benefit. Please continue but remember you have to "show your work", that is, you have to explain what you have tried, or what you think the specific soli
Yes i know that, thank you
 
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