How is the baseline computed

[mbouzarouata]

Hello,

I need to understand how is the baseline computed, if possible I want to have the exact formula.

Thank you for your help

[mbouzarouata]

I am using a CY8C20110 QFN16.

[ncbs · Accepted solution]

Hi @mbouzarouata ,

The baseline is the filtered version of the raw count. When the raw count is within "baseline + noise threshold", then the baseline tracks the raw count, else it doesn't i.e., if the current raw count is higher than the baseline by a value greater than the noise threshold, the baseline remains at a constant value equal to the prior baseline value.

When the current raw count drops below "baseline - negative noise threshold", then the baseline remains constant to its previous value for "low baseline reset" number of cycles. If the baseline is still below "baseline - negative noise threshold", then baseline gets reset to the current raw count value.

Regards,
Nikhil

[mbouzarouata]

Hi Nickhil @ncbs ,

Thank you, I understand that :

- as long as : [baseline - negative noise threshold < raw count < baseline + noise threshold] and the number of raw counts that meets this criteria is above the value defined in baseline update threshold then : 

      -  new value of baseline = old value of baseline + 1?

- once a value of raw count doesn't meet the criteria above, the buffer baseline update threshold is not incrmented nor reinitialised to 0? it stays constant if  [baseline + noise threshold < raw count < baseline + finger threshold] and it takes the raw count value if the number of [raw counts < baseline - negative threshold] is > low baseline reset?

Am I correct ?

[ncbs]

Hi @mbouzarouata ,

Yes, if baseline - negative noise threshold < raw count < baseline + noise threshold, then the new value of baseline = old value of baseline ± 1.

If the raw counts > baseline + noise threshold, then the baseline is not updated, and the last updated value is maintained as the baseline.

If raw counts < baseline - negative noise threshold for more than "low baseline reset" number of cycles, then baseline takes the value of raw count.

Regards,
Nikhil