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Purpose of Modulation frequency of 5KHz on CN0312 and CN0363 Evaluation Borads

Hi,

I am using CN0312 Evaluation board to measure the absorption characteristics of different samples.

My question is why is there a need of modulation frequency for the LED i.e. 5KHZ or any other frequency on CN0312 and also CN0363.

The reason why i am confused is because there is no option for changing duty cycle in the software which could have allowed us to change the LED's brightness.

So, if we are not changing LED's brightness then what is the purpose of just modulation  for this specific application and why didn't you used just normal non-modulated dc source for this purpose?

Does it have anything to do with the Photodiode used in the board? Because I couldn't find anything conclusive.

Thanks in advance.

Regards,

Umer

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  • Hi Umer,

    Using synchronous detectors both boards use frequency modulation to reject signal that are not the same as the frequency used to drive the LED. While CN0312 has a fixed frequency at 500kHz, CN0363 is able to change the excitation frequency via its software.

    If you would like to learn more about synchronous detectors please visit this link>> Synchronous Detectors

    Regards,

    Glenn

Reply
  • Hi Umer,

    Using synchronous detectors both boards use frequency modulation to reject signal that are not the same as the frequency used to drive the LED. While CN0312 has a fixed frequency at 500kHz, CN0363 is able to change the excitation frequency via its software.

    If you would like to learn more about synchronous detectors please visit this link>> Synchronous Detectors

    Regards,

    Glenn

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