hi sir
i have problem that in msp430fg439 having application which is in the medical portion pulse oximeter in that i found one difficulty is that in the programming SpO2 look up table offset and Ratio offset what is the difference how they make it from which reference they have decided it please sir help me
i am going to mention the program where they have done it .
/* SaO2 Computation */
x = log_sq_ir_heart_ac_signal/log_heart_signal_sample_counter;
y = log_sq_vs_heart_ac_signal/log_heart_signal_sample_counter;
Ratio = (unsigned int) (100.0*log(y)/log(x));
if (Ratio > 66)
SaO2 = Lookup[Ratio - 66]; // Ratio - 50 (Look-up Table Offset) - 16 (Ratio offset) /// my question over here only how they have decided ???
else if (Ratio > 50)
SaO2 = Lookup[Ratio - 50]; // Ratio - 50 (Look-up Table Offset)
else
//SaO2 = 100;
SaO2 = 99;
and sir i show the look up table also so u can able to judge it
// SaO2 Look-up Table
const unsigned int Lookup [43] = {100,100,100,100,99,99,99,99,99,99,98,98,98,98,
98,97,97,97,97,97,97,96,96,96,96,96,96,95,95,
95,95,95,95,94,94,94,94,94,93,93,93,93,93};
and also i show the my look up table which i have design for my application because above one will not show the lower SpO2 % thatswhy ..i show my look up table
const unsigned int Lookup [160] ={
93,93,93,92,92,92,91,91,91,91,90,90,90,90,89,89,89,89,88,88,88,88,87,87,87,87,
86,86,86,86,85,85,85,85,84,84,84,84,83,83,83,83,82,82,82,82,81,81,81,81,80,80,
80,80,79,79,79,79,78,78,78,78,77,77,77,77,76,76,76,76,75,75,75,75,74,74,74,73,
73,73,72,72,72,71,71,71,70,70,70,69,69,69,68,68,67,67,67,67,66,66,66,65,65,65,
64,64,64,63,63,63,62,62,62,62,61,61,61,61,60,60,60,59,59,59,58,58,58,57,57,57,
56,56,56,56
};
in my case i have to change that value otherwise i am not able to get the accurate result, so please give answer with proper explanation that how should calculate the ratio offset and look up table offset ..