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08-02-2020 12:56 AM

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I am using a thermopile whose dataset is available around 38301 values. This is purely mathematical query. Need to find two unknowns in below equation:

Vtp = K( Tobj^(4-n) - Ta^(4-n) )

Company says K & n are empirically determined value & this they wont tell.

Vtp is in volts

Tobj & Ta are in kelvins

Here is 38301 dataset: https://drive.google.com/file/d/1Kzok_MVeLRNiUz59HZl6xHrpkh5dg3mg/view?usp=sharing

Again this is purely mathematical query, just to see if it can be find out.

From these 38301 dataset values, we need to find best fit values of K & n, so that in final calculations when Tobj is to be calculated from known values of Vtp,Ta,K & n, this has minimum error.

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08-02-2020 02:56 AM - edited 08-02-2020 02:57 AM

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After all our discussions last months, this seems trivial. What have you tried?

You can fit for the best parameters using the current formula, but to calculate Tobj, you need to solve for Tobj, of course. Doesn't look hard.

The column labels in your data file make no sense. Tntc does not show in your formula, and why are they to the fourth power. (Tobj^4, Tntc^4). if these are really the values, shouldn't the units be Kelvin^4? I can guarantee that you don't need 20+ significant digits for VTP. What a waste of bytes! How many bits does the digitizer actually have?

Please clarify.

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08-02-2020 03:38 AM

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1. Sorry this is NTC and Tobj tempearture in kelvin. This ^4 is wrong mentioned. This is typo. Please ignore

2. My actual area of interest was 30 to 47C obj & Tntc=0 to 50, I have been able to make equation with +-0.07C in this region , my practical purpose is solved.

3. This is just mathematical thing, i want to see if it can fit mathematically also thats it.

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08-03-2020 03:31 AM - edited 08-03-2020 03:32 AM

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Hi Vindhy,

@Vindhyachal.Takniki wrote:

2. My actual area of interest was 30 to 47C obj & Tntc=0 to 50

3. This is just mathematical thing,

.i want to see if it can fit mathematically also thats it

Here you can see the result after applying "mathematically fit":

I used the range from -50°C…100°C…

Best regards,

GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO

GerdW

using LV2011SP1 + LV2017 (+LV2020 sometimes) on Win10+cRIO